MECHANICS
OF THE
HOUSEHOLD

A COURSE OF STUDY DEVOTED TO
DOMESTIC MACHINERY AND
HOUSEHOLD MECHANICAL
APPLIANCES

E. S. KEENE

DEAN OF MECHANIC ARTS
NORTH DAKOTA AGRICULTURAL COLLEGE

First Edition

McGRAW-HILL BOOK COMPANY, Inc.
239 WEST 39TH STREET. NEW YORK

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LONDON: HILL PUBLISHING CO., Ltd.
6 & 8 BOUVERIE ST., E. C.

1918

Copyright, 1918, by the
McGraw-Hill Book Company, Inc.

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[v]

INTRODUCTION

This book is intended to be a presentation of the physical principles and mechanism employed in the equipment that has been developed for domestic convenience. Its aim is to provide information relative to the general practice of domestic engineering. The scope of the work is such as to present: first, the use of household mechanical appliances; second, the principles involved and the mechanism employed. It is not exhaustive, neither does it touch many of the secondary topics that might be discussed in connection with the various subjects. It does, however, describe at least one representative piece of each type of household apparatus that is used in good practice.

The mechanism used in the equipment of a modern dwelling is worthy of greater attention, as a course of study, than it has been heretofore accorded. The fact that any house, rural or urban, may be provided with all domestic conveniences included in: furnace heating, mechanical temperature regulation, lighting facilities, water supply, sewage disposal and other appliances, indicates the general use of domestic machinery in great variety. To comprehend the application and adaptability of this mechanism requires a knowledge of its general plan of construction and principles of operation.

Heating systems in great variety utilize steam, hot water, or hot air as the vehicle of transfer of heat from the furnace, throughout the house. Each of these is made in the form of special heating plants that may be adapted, in some special advantage to the various conditions of use. A knowledge of their working principles and general mechanical arrangement furnishes a fund of information that is of every day application.

The systems available for household water distribution take advantage of natural laws, which aided by suitable mechanical devices and conveniently arranged systems of pipes, provide water-supply plants to satisfy any condition of service. They may be of simple form, to suit a cottage, or elaborated to the requirements of large residences and made entirely automatic in[vi] action. In each, the apparatus consists of parts that perform definite functions. The parts may be obtained from different makers and assembled as a working unit or the plant may be purchased complete as some special system of water supply. An acquaintance with domestic water supply apparatus may be of service in every condition of life.

The type of illumination for a house or a group of buildings, may be selected from a variety of lighting systems. In rural homes, choice may be made between oil gas, gasolene, acetylene and electricity, each of which is used in a number of successful plants that differ only in the mechanism employed.

Any building arranged with toilet, kitchen and laundry conveniences must be provided with some form of sewage disposal. Private disposal plants are made to meet many conditions of service. The mechanical construction and principles of operation are not difficult to comprehend and their adaptation to a given service is only an intelligent conception of the possible conditions of disposal, dependent on the natural surroundings.

There are few communities where household equipment cannot be found to illustrate each of the subjects discussed. Most modern school houses are equipped for automatic control of temperature, ventilation and humidity. They are further provided with systems of gas, water and electric distribution and arrangements for sewage disposal. These facilities furnish demonstration apparatus that are also examples of their application. Additional examples of the various forms of plumbing and pipe fittings, valves, traps and water fixtures may be found in the shop of dealers in plumbers and steam-fitters supplies.

Attention is called to the value of observing houses in process of construction and the means employed for the placement of the pipes for the sewer, gas, water, electric conduits, etc. These are generally located by direction of the specifications provided by the architect but observation of their installation is necessary for a comprehension of actual working conditions. It is suggested that the work be made that of, first, acquiring an idea of established practice, and second, that of investigating the examples of its application.

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[vii]

CONTENTS

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MECHANICS OF THE HOUSEHOLD

[1]

CHAPTER I
THE STEAM HEATING PLANT

The use of steam as a means of heating dwellings is common in every part of the civilized world. Plants of all sizes are constructed, that not only give satisfactory service but are efficient in the use of fuel, and require the minimum amount of attention.

The manufacture of steam heating apparatus has come to be a distinct industry, and represents a special branch of engineering. Many manufacturing companies, pursue this line of business exclusively. The result has been the development of many distinctive features and systems of steam heating, that are very excellent for the purposes intended.

Practice has shown that large plants can be operated more economically than small ones. Steam may be carried through underground, insulated pipes to great distances with but small loss of heat. This has lead to the sale of exhaust steam, from the engines of manufacturing plants, for heating purposes and the establishment of community heating plants, where the dwellings of a neighborhood are heated from a central heating plant; each subscriber paying for his heat according to the number of square feet of radiating surface his house contains.

In the practice most commonly followed, with small steam heating plants, the steam is generated in a boiler located at any convenient place, but commonly in the basement. The steam is distributed through insulated pipes to the rooms, where it gives up its heat to cast-iron radiators, and from them it is imparted to the air; partly by radiation but most of the heat is transmitted to the air in direct contact with the radiator surface.

The heating capacity of a radiator is determined by its outside surface area, and is commonly termed, radiating surface or heating surface. Radiators of different styles and sizes are listed by manufacturers, according to the amount of heating surface[2] each possesses. Radiators are sold at a definite amount per square foot, and may be made to contain any amount of heating surface, for different heights from 12 to 45 inches.

The widespread use of steam as a means of heating buildings is due to its remarkable heat content. When water is converted into vapor the change is attended by the absorption of a large amount of heat. No matter at what temperature water is evaporated, a definite quantity of heat is required to merely change the water into vapor without changing its temperature. The heat used to vaporize water in a steam boiler is given up in the radiators when the steam is condensed. It is because of this property that steam is such a convenient vehicle for transferring heat from the furnace—where it is generated—to the place to be warmed. This heat of vaporization is really the property which gives to steam its usefulness as a means of heating.

Heat of Vaporization.

—The temperature of the steam is comparatively an unimportant factor in the amount of heat given up by the radiator. It is the heat liberated at the time the steam changes from vapor to water that produces the greatest effect in changing the temperature of the house. This evolution of heat by condensation is sometimes called the latent heat of vaporization. It is the heat that was used up in changing the water to vapor. The following table of the properties of steam shows the temperatures and exact amounts of latent heat that correspond to various pressures.

When water at the boiling point is turned into steam at the same temperature, there are required 965.7 B.t.u. for each pound of water changed into steam. In the table, this is the latent heat of the vapor of water at 0, gage pressure. As the pressure and corresponding temperature rise, the latent heat becomes less. At 10 pounds gage pressure, the temperature of the steam is practically 240°F., but the heat of vaporization is 946 thermal units. When the steam is changed back into water, as it is when condensed in the radiators, this latent heat becomes sensible and is that which heats the rooms. The steam enters the radiators and, coming into contact with the relatively colder walls, is condensed. As condensation takes place, the latent heat of the steam becomes sensible heat and is absorbed by the radiators and then transferred to the air of the rooms.

[3]

Properties of Steam

Whenever water is evaporated, heat is used up at a rate that in amount depends on its temperature and the quantity of water vaporized. This heat of vaporization is important, not only in problems which relate to steam heating but in all others where vapor of water exerts an influence—ventilation of buildings, atmospheric humidity, the formation of frost, refrigeration, and many other applications in practice; this factor is one of the important items in quantitative determinations of heat. It will appear repeatedly in considering ventilation and humidity.

At temperatures below the boiling point of water, the heat of vaporization gradually increases until, at the freezing point, it is 1092 B.t.u. Water vaporizes at all temperatures—even ice evaporates—and the cooling effect produced by evaporation[4] from sprinkled streets in summer, or the chilling sensation brought about by the winds of winter are caused largely because of its effect. The evaporation of perspiration from the body is one of the means of keeping it cool. At the temperature of the body 98.6 the heat of vaporization is 1046 B.t.u.

Steam Temperatures.

—While the temperature of steam is an unimportant factor in the heating of buildings there are many uses in which it is of the greatest consequence. When steam is employed for cooking or baking it is not the quantity of heat but its intensity that is necessary for the accomplishment of its purpose.

Steam cookers must work at a temperature suitable to the articles under preparation, and the length of time required in the process. Examination of the table on page 3, will show that steam at the pressure of the air or 0, gage pressure, has a temperature of 212°F., which for boiling is sufficiently intense for ordinary cooking; but for all conditions required of steam cooking, a pressure of 25 pounds gage pressure is required. The temperature corresponding to 25 pounds is shown in the table as 267°F. Baking temperatures for oven baking as for bread requires temperatures of 400°F. or higher. To bake by steam at that temperature would require a gage pressure of 185 pounds to the square inch.

The British thermal unit is the English unit of measure of heat. It is the amount of heat required to raise the temperature of a pound of water 1°F. From the table it will be seen that steam at 10 pounds gage pressure, is only 27.4° hotter than it was at 0 pounds. In raising the pressure of a pound of steam from 0 to 10 pounds, the steam gained only 27.4 B.t.u. of heat. The amount of heat gained by raising the pressure to 10 pounds is small as compared with the heat it received on vaporizing. The extra fuel used up in raising the pressure is not well expended. It is customary, therefore, in heating plants, to use only enough pressure in the boiler to carry the steam through the system. This amount is rarely more than 10 pounds and oftener but 3 or 4 pounds pressure.

Gage Pressure—Absolute Pressure.

—In the practice of engineering among English speaking people, pressures are stated in pounds per square inch, above the atmosphere. This is termed[5] gage pressure. It is that indicated by the gages of boilers, tanks, etc., subjected to internal pressure. Under ordinary conditions the term pressure is understood to mean gage pressure, the 0 point being that of the pressure of the atmosphere. This system requires pressures below that of the atmosphere to be expressed as a partial vacuum, a complete vacuum being 14.7 pounds below the normal atmospheric pressure.

In order to measure positively all pressures above a vacuum, the normal atmosphere is 14.7 pounds; all pressures above that point are continued on the same scale, thus:

Gage pressure 0 = 14.7 absolute
Gage pressure 10 = 10 + 14.7 = 24.7 absolute
Gage pressure 20 = 20 + 14.7 = 34.7 absolute

Absolute pressures are, therefore, those of the gage plus the additional amount due to the atmosphere. All references to pressure in this work are intended to indicate gage pressure unless specifically mentioned as absolute pressure.

Steam heating as applied to buildings may be considered under two general methods: the pressure system in which steam under pressure above the atmosphere is utilized to procure circulation; and the vacuum system in which the steam is used at a pressure below that of the atmosphere. Each of these systems is used under a great variety of conditions, and to some is applied specific names but the principle of operation is very much the same in all of a single class.

Steam heating plants are now seldom installed in the average home but they are very much employed in apartment houses and the larger residences. In large buildings and in groups of buildings heated from a central point, steam is used for heating almost exclusively. The type of plant employed for any given condition will depend on the architecture of the buildings and their surroundings. In very large buildings and in groups of buildings, the vacuum system is very generally employed. This system has, as a special field of heating, the elaborate plants required in large units.

The low-pressure gravity system of heating is used in buildings of moderate size, large residences, schools, churches, apartment houses, and the like. Under this form of steam heating is[6] to be included vapor heating systems. This is the same as the low-pressure plant except that it operates under pressure only slightly above the atmosphere and possesses features that frequently recommend its use over any other form of steam heating. The term vapor heating is used to distinguish it from the low-pressure system.

The low-pressure gravity system, with which we are most concerned, takes its name from the conditions under which it works. The low pressure refers to the pressure of the steam in the boiler, which is generally 3 or 4 pounds; and since the water of condensation flows back to the boiler by reason of gravity, it is a gravity system.

The placing of the pipes which are to carry the steam to the radiators and return the water of condensation to the boiler may consist of one or both of two standard arrangements. They are known as the single-pipe system and the two-pipe system.

Fig. 1 shows a diagram of a single-pipe system in its simplest form. In the figure the pipe marked supply and return, connects the boiler with the radiators. From the vertical pipe called a riser, the steam is taken to the radiators through branch pipes that all slope toward the riser, so that the water of condensation may readily flow back into the boiler. The water of condensation, returning to the boiler, must under this condition, flow in a direction contrary to the course of the steam supplying the radiators. In Fig. 2 is given a simple application of this system. A single pipe from the top of the boiler, in the basement, marked supply and return pipe, connects with one radiator on the floor above. The[7] radiator and all of the connecting pipes are set to drain the water of condensation into the boiler.

When the valve is opened to admit steam to the radiator, the air vent must also be opened to allow the escape of the contained air. The steam will not diffuse with the air in the radiator and unless the air is allowed to escape, the steam will not enter. As the steam enters the cold radiator, it is rapidly condensed, and collects on the walls in the form of dew, at the same time giving up its latent heat. The heat is liberated as condensation takes place, and as the dew forms on the radiator walls the heat is conducted directly to the iron. The water runs to the bottom of the radiator and then through the pipes; back to the boiler. The water occupies but relatively a little space and may return through the same pipe, while more steam is entering the radiator. As the steam condenses in the radiator, its reduction in volume tends to reduce the pressure and thus aids additional steam from the boiler to enter. In this manner a constant supply of heat enters the radiator in the form of steam which when condensed goes back to the boiler at a temperature very near the boiling point to be revaporized. It should be kept in mind that it is the[8] heat of vaporization, not the temperature of the steam that is utilized in the radiator, and that the heat of vaporization is the vehicle of transfer. The water returning to the boiler may be at the boiling point and the steam supplying the heat to the radiators may be at the same temperature.

Fig. 3 is a slightly different arrangement of the same boiler as that shown in Fig. 2, connected with two radiators on different floors. The same riser supplies both radiators with steam and takes the water of condensation back to the boiler.

Fig. 4 is an example of the single-pipe system applied to a small house. In the drawing, the boiler in the basement is shown connected with four radiators on the first floor and three on the second floor. The pipes connecting with the more distant radiators are only extensions of the pipes connecting the radiators near[9] the boiler. As in Figs. 1, 2 and 3, all of the pipes and radiators are set to drain back into the boiler. If at any place the pipe is so graded that a part of the water is retained, poor circulation will result, because of the restricted area of the pipe, and the radiators will not be properly heated. This lack of drainage is also a common cause of hammering and pounding in steam systems, known as water-hammer. The formation of water-hammer is caused by steam flowing through a water-restricted area, into a cold part of the system, where condensation takes place very rapidly. The condensation of the steam is so rapid and complete that the resulting vacuum draws the trapped water into the space with the force of a hammer stroke. The hammering will continue so long as the conditions exist. The pipes in the basement are suspended from the floor joists by hangers as shown in the drawing. In practice the pipes in the basement are covered with some form of insulating material to prevent loss of heat.

As stated above, the single-pipe system may be successfully used in all house-heating plants except those of large size. It[10] requires the least amount of pipe and labor for installation of the circulating system and when well constructed performs very satisfactorily all of the functions required in a small heating plant.

One of the commonest causes of trouble in a single-pipe system is due to the radiator connections. The single radiator connection requires the entering steam and escaping water of condensation to pass through the same opening. Under ordinary conditions this double office of the radiator valve is accomplished with satisfaction but occasionally it is the cause of considerable noise. At any time the valve is left only partly open the steam will enter and condense because of the lower pressure inside the radiator but the condensed water will not be able to escape. The water has only the force of gravity to carry it out of the radiators and if it meets no opposition will flow back through the pipe to the boiler; but if it is required to pass a small opening through which steam is flowing in a contrary direction, the water will be retained in the radiators. Single-pipe radiators, therefore, work satisfactorily only under conditions which will permit the steam to enter and the water to leave as fast as it is formed. In ordinary use the valve at any time is apt to be left slightly open and this produces undesirable working conditions.

In larger buildings, where greater distances require longer runs of pipe and more complicated connections, and where the volume of condensed steam is too great to be taken care of in a single pipe, this system does not work satisfactorily.

Two-pipe System.

—Fig. 5 is a diagram of a two-pipe system. Here, each radiator has a supply pipe, through which the steam enters, and a return pipe which conducts the water away. The branch pipes from a common supply pipe or riser, carry steam to the various radiators and all of the return pipes empty into a single return pipe that takes the water back to its source. It will be noticed that in this case the riser also connects at the bottom with the return pipe. This connection is made for the purpose of conducting away the condensation that takes place in the connecting pipes. The water will always stand in these pipes, at the same height as the water in the boiler. The supply pipe from the boiler, and the branch pipes connecting the radiators all slope toward the riser. The condensation in the connecting pipes does not pass through the radiators as it returns to the boiler.

[11]

An exception to this general rule is shown in the radiator on the second floor. In this case the supply pipe slopes downward as it approaches the radiator. To prevent carrying water through the radiator, a small pipe under the left-hand valve connects with the return pipe and the water is thus conducted to the main return pipe.

Fig. 6 is a simple application of the arrangement shown in Fig. 5. The steam may be easily traced from the boiler to the radiators, and back through the return pipes to its source. The pipe marked R is the connection between the main supply pipe and the return pipe that takes away the condensation of the riser. It is connected to the main return pipe below the water line of the boiler and, therefore, does not interfere in any way with the passage of the steam. Each radiator empties its water of condensation into a common return pipe, that finally connects with the boiler below the water line.

This arrangement may be elaborated to almost any extent and is an improvement over the single-pipe system. It is quite commonly used as a method of steam distribution, but it lacks the required elements necessary to a positive circulation. As an example: Suppose that the plant shown in Fig. 6 is working and that the radiator on the first floor is hot, but the valves of the radiator on the second floor are closed and it is cold. The steam entering at the valve A of the lower radiator is being condensed as fast as the heat is radiated. The steam will pass on through the valve B into the return pipe and as soon as the return pipe[12] becomes hot it will contain steam at practically the same pressure as that in the supply pipe. This is what takes place in every working steam plant. Now suppose that it is desired to heat the radiator on the floor above. The steam valve A of the upper radiator is opened to admit steam and the return valve is also opened to allow the water to escape. There is steam in both the supply and return pipes of the radiator below at the same pressure, each tending to send steam into the radiator above at opposite ends. This would make a condition exactly the same as a single-pipe system, with a supply pipe at both ends of the radiator and the result would, of course, be the same as in the single-pipe system. There being no place for the water to escape except against the incoming steam, the water will sometimes surge back and forth with the customary noises peculiar to such conditions. It must not be understood that this will always occur, because[13] systems of this kind are in use with fairly good results, but noisy radiators are not at all rare when working under this condition and the cause is from that described. To overcome this difficulty and change the system into one in which there would be a positive circulation from A to B, in each radiator, allowing the steam always to enter at the valve A and escape at B, the system must be changed to that of separate returns.

Separate-return System.

—A diagram of a separate-return system is shown in Fig. 7. In this figure, the radiator, boiler and supply pipes are the same as those of Fig. 5, but there is a separate return pipe from each of the radiators, connecting with the main return pipe at a point below the water line of the boiler. Examination of this diagram will show that there is an independent circuit for the steam through each radiator. The steam is taken from a common riser as before but after passing through the radiator the water is returned by a separate pipe to the main return pipe at the bottom of the boiler. Fig. 8 is an application of separate-return system. It is exactly the same as Fig. 6, except that each radiator has an independent return pipe. Steam must always enter the radiators at the valves A and leave at the valves B. This makes a positive circulation that renders each radiator independent of the others. There is no opportunity for steam to pass through one radiator and interfere with the return water of another; it, therefore, prevents the possibility of hammering or surging so common in poorly designed steam systems.

[14]

Of all the methods of steam heating where the water of condensation is returned to the boiler by reason of gravity this is the most satisfactory. This plant requires a larger amount of pipe than the other systems described and as a consequence the cost of installation is greater but it repays in excellence of service the extra expense incurred.

Overhead or Drop System.

—There is yet another gravity system of steam heating that is sometimes used in large buildings where economy in the use of pipe is desired; this is the overhead or drop system shown in Fig. 9. It is not a common method of piping and is given here only because of its occasional use. In the arrangement of the drop system, the supply pipe for the radiators rises from the boiler to the highest point of the system and the branch pipes for the radiators are taken off from the descending pipe. Its action is the same as that of a single-pipe[15] system but the advantage gained by the arrangement is that the steam in the main supply pipes travels in the same direction as the returning water of condensation; the cause of surging in long risers is thus eliminated.

The two-pipe systems of steam heating are more certain in action than the single-pipe methods because there is nothing to interfere with the progress of the steam on its way to the radiators. In long branch pipes of the single-pipe system, the returning water is frequently caught by the advancing steam and carried to the end of the pipe, when slugging and surging is the result.

Water-filled Radiators.

—Radiators frequently fill with water and are noisy because of the position of the valve. This may be true in any gravity system but particularly so in radiators having a single pipe. When the valve of a single-pipe radiator is opened a very small amount, the entering steam is immediately condensed but the water cannot escape because the incoming steam entirely fills the opening. Under this condition, the radiator may entirely fill with water. If the valve is then opened wide, the imprisoned water has an opportunity to escape while the steam is entering, but the entering steam and escaping water sets up a water-hammer that sometimes is terrific and lasts until the water is discharged from the radiator. The same condition may exist in a two-pipe system, if the steam valve is slightly opened while the escape valve is closed, but in a well-designed system the radiator will be immediately emptied when both valves are open.

[16]

Air Vents.

—All radiators must be provided with air vents. The vent is placed near the top of the last loop of the radiator, at the end opposite from the entering steam, as indicated in Figs. 2, 3, 6, etc. The object of the vent is to allow the air to escape from the radiator as the steam enters. Steam will not diffuse with the air and, therefore, cannot enter the radiator until the air is discharged. The air vent may be a simple cock such as is shown in Fig. 10, that must be opened by hand when the steam is turned on, to allow the air to escape, and closed when the steam appears at the vent; or it may be an automatic vent, that opens when the radiator cools and closes automatically when the radiator is filled with steam. There are many makes of air vents of both hand-regulating and automatic types; of the former, Fig. 10 furnishes a common example. The part A, in the figure, is threaded and screws tightly into a hole made to receive it in the end loop of the radiator. The part B is a screw-plug that closes the passage C, leading to the inside of the radiator. When the steam is turned on, the vent must be opened until the air is discharged, after which it is closed by the hand-wheel D.

Automatic Air Vents.

—These vents depend for their action on the expansion of a part of the valve due to the temperature of the steam. The valve remains closed when hot and opens when cold. The difference in temperature between the steam and the expelled air from the radiator is the controlling factor. In the[17] automatic vent shown in Fig. 11, the part A is screwed into the radiator loop. The discharge C is open to the air or connected with a drip pipe, which returns the water to the basement. The cylinder D, which closes the passage B, is made of a material of a high coefficient of expansion. The piece D, when cool, is contracted sufficiently to leave the passage B open to the air. When the steam is turned on, the expelled air from the radiator escapes through B and C, but when the steam reaches D the heat quickly expands the piece and closes the vent.

Most automatic vents require adjusting when put in place and occasionally need readjustment. The cap O, of Fig. 11, may be removed with a wrench and a screw-driver used to adjust the piece D, so as to shut off the steam when the radiator is filled with steam. The expanding piece is simply screwed down until the steam ceases to escape.

Fig. 12 is another style of automatic vent, constructed on the same principle as that of Fig. 11, but probably more positive in action. In this vent the part A attaches to the radiator. The expanding portion B is made in the form of a hollow cylinder, through which the air and steam escape to the atmosphere. It is longer than the corresponding piece in the other vent and is more sensitive because of its greater length and exposed surface. As the piece B elongates from expansion, the upper end makes a joint with the conical piece D. The shape of this latter piece gives better opportunity for a tight joint than in the other form of vent and in practice gives better service.

Fig. 13 is a cross-section of the Allen vent. This is an example of a vent which depends for its action on a float. Whenever sufficient water accumulates in the body of the vent to raise the float, it closes the vent by means of its buoyancy. The body of the vent shown in Fig. 13 is composed of two concentric cylinders. The float E occupies the inner cylinder, while surrounding it is the outer cylinder D. The outer cylinder is entirely closed except a little hole at G. The float is made of light metal and fits loosely in the inner cylinder. The steam from the radiator condenses in the vent until the inner cylinder is filled with water, up to the opening A. The float by its buoyancy keeps the opening in B stopped, and no steam can escape. The air of the outer cylinder D is expanded by the heat of the steam and most of the[18] air escapes through the hole G. When the radiator cools, the rarefied air in D contracts and draws the water from the inner cylinder into the space D; this allows the float to fall and unstop the opening in B. When the steam again reaches the vent, the heat expands the air in D and forces the water into the inner cylinder; the float is again raised and stops the opening in B.

Many other air vents are in common use but most of them operate on one or the other of the principles described. Fig. 11 is a relatively inexpensive vent, while Fig. 12 is higher-priced.

Steam Radiator Valves.

—Like most other mechanical appliances that are extensively used, radiator valves are made by a great number of manufacturers and in many different forms. Some possess special features that are intended to increase their working efficiency but the type of radiator valve most commonly used for ordinary construction is that illustrated in Figs. 14 and 15. It is a style of angle valve that takes the place of an elbow and being made with a union joint, also furnishes a means of disconnecting the radiator without disturbing the pipes. Fig. 14 is an outside view of the valve and Fig. 15 shows its mechanical construction. The part B screws onto the end of the steam pipe and A connects with the radiator. The part C-D is the union. The nut C screws onto the valve and makes a steam-tight[19] joint at D, between the parts. In case it is desired to remove the radiator, it furnishes an easy means of detaching the valve. The composition valve-disc E makes a seat on the brass ring directly under it, to shut off the steam. In case the valve leaks, the disc may be removed by taking the valve casing apart at G. The worn disc can then be replaced with a new one which may be obtained from the dealer who furnished the valve. The only moving part of the valve exposed to the air is at the point where the valve-stem S enters the casing. The joint is made steam-tight by the packing P. The packing is greased candle wicking that is wound around the stem and held tightly in place by the screw-cap H. If the valve leaks at this joint, a turn or two with a wrench will stop the escape of the steam.

THE HOUSE-HEATING STEAM BOILER

House-heating boilers were formerly made of sheet metal and are still so constructed to some extent, but by far the greater number are now made of cast iron. Sheet-metal boilers are constructed at the factory, ready to be installed, but the cast-iron type is made in sections and assembled to make a complete boiler, at the time the plant is erected. Sectional boilers are convenient to install, on account of the possibility of handling the parts in a limited space, that would not admit an assembled boiler without tearing down a part of the basement for admission.

Cast-iron boilers as commonly used for heating dwellings are made in two definite styles. The small sizes are cylindrical in form and are used for either steam or hot-water heating. The larger sizes are made as illustrated in Figs. 16 and 17, the former being an outside view, and the latter showing the internal arrangement of the same boiler. The fire-box, water space and smoke passages are easily recognized. Each division represents a separate section which assembled as that in the figures makes a complete boiler with a common opening as shown at the top of Fig. 17. These boilers are used for residences of large size and for buildings of less than 10,000 feet of radiating surface. For large buildings, the steam is most commonly generated in boilers built for high pressure.

In small plants, intended for either steam or hot-water heating,[20] the cylindrical style of boiler shown in Fig. 18 is commonly used. As constructed by different manufacturers, the parts differ quite materially but Fig. 18 shows all of the essential features and serves to illustrate the different working parts. The sections into which the boiler is divided are indicated on the left-hand side of the figure by the numbers 1 to 6. The parts from 1 to 5 are screwed together with threaded nipples, joining the central column. The part 6 contains the grate and the ash-pit, with the draft and clean-out doors.

The drawing shows the boiler cut through the middle lengthwise and exposes to view all of the essential features. The fire-box and the spaces occupied by the steam and water are easily recognized. It will be seen that the water space surrounds the fire-box except at the bottom and that the space above the fire-box presents a large amount of heating surface to the flame and heated gases as they pass to the chimney. The arrows show their course; first through the openings near the center, then through those further away. The object being to keep the[21] heat as long as possible in contact with the heating surfaces without interfering with the draft.

There is no standard method of rating the heating capacity of boilers of this kind and as a consequence, boilers of different makes—for the same rating—are not the same in actual heating capacity. The boilers are sold by their makers in sizes that are intended to furnish heat sufficient to supply a definite number of square feet of radiating surface. The ratings are quite generally too high for the weather conditions of the Northwest. A common practice with contractors is to select boilers for a given plant 50 per cent. and even 100 per cent. larger than those rated by the manufacturers for the same amount of radiation.[22] Some manufacturers sell their boilers at honest ratings but they are exceptions.

In specifying the capacity of a house-heating plant it is common practice to require the boiler to be of such size as will easily heat a definite number of square feet of radiating surface. The radiators are required to possess sufficient radiating surface to keep the house at 70°F. in any weather. In the absence of any rules or specifications for determining the heating capacity of the boiler, the only means of securing a satisfactory plant is to require a guarantee of the contractor to install a boiler such as will fulfil the conditions stated above.

Boiler Trimmings.

—Attached to the boiler and required for its safe operation are a number of appliances that demand special attention. The office of each part should be thoroughly appreciated and the mechanical construction should be fully understood. An intimate acquaintance with the details of the plant, helps to make its operation satisfactory and adds to the efficiency with which it can be made to perform its duty.

The object of the gage-glass is to show the height of the water in the boiler. It is shown in place on the boiler in Figs. 16 and 18 and in detail in Fig. 19. The lower part of the gage-glass occupies a position on the boiler about 2 inches above the top heating surface. When the boiler is working, the level of the water should always be visible in the glass and should stand normally one-third to one-half full.

The water gage is attached to the water column by two brass valves V. The valves are provided so that in case the water[23] glass should be broken the openings may be closed. The ends of the glass are made tight by “stuffing-boxes” marked C, in the figure. The packing S is generally in the form of rubber rings but greased wicking may be used if necessary as in the case of valve-stems.

The try-cocks T and T (Fig. 18) are also intended to indicate the approximate height of the water in the boiler and should the water glass be broken may be used in its place. The openings of the try-cocks point toward the floor. When a cock is opened, should steam alone escape, it will be absorbed by the air, but if water is escaping, although much of it will be vaporized and look like steam, some of the water will be carried to the floor and produce a wet spot. When the cock is opened wide the escaping water from the lower cock should always wet the floor.

The drip-cock P (Fig. 18) at the bottom of the gage-glass is for draining the water column and for blowing out any deposit that may collect in the opening of the column. This cock should be opened occasionally to assure the correctness of the gage-glass.

The Steam Gage.

—Steam pressure is measured in pounds to the square inch above the pressure of the atmosphere. The gages used for indicating the pressure of the steam are made in several forms but the type most commonly used is that shown in Fig. 20. It is known as the Bourdon type of gage and takes its name from the bent tube A, which furnishes its active principle. The Bourdon barometer invented in 1849 employed this form of sensitive tube. In the drawing the face of the gage has been removed to show the working parts. The sensitive part is the flat elastic tube A, which is bent in the form of a circle. When the pressure of the steam enters at S the air in the tube is compressed and the tube tends to straighten. The movement of the tube caused by the steam pressure is communicated to the pointer by a link connection and gear as shown in the drawing. The amount of straightening of the tube will be in proportion to the steam pressure and is indicated by the numbers marked on the face of the gage. When the pressure is[24] released, the tube returns to its original position and the spiral spring C turns the hand back to its first position.

The Safety Valve.

—All steam boilers should be provided with safety valves as a safeguard against excessive steam pressures. Of the various types of safety valves, that known as the pop-valve is most commonly used on house-heating boilers. It is indicated at W in Fig. 18 and is shown in section in Fig. 21. The part A is screwed into the top of the boiler at any convenient place. The pressure of the spring C holds the valve B on its seat until the internal pressure reaches a certain intensity at which the valve is set, when it opens and allows the excess steam to escape. When the pressure is reduced, the spring forces the valve back on its seat. The handle D permits the valve to be lifted at any time as an assurance that it is in working order. This should be done occasionally, as the valve may stick to the seat after long standing and allow the pressure to rise above the point at which it should “pop.”

The valve may be set to “blow off” at any desired pressure by the adjusting piece E. House-heating boilers generally have their safety valves set to blow off at 8 or 10 pounds.

The Draft Regulator.

—As a means of automatic control of the steam pressure, the draft regulator is frequently used to so govern the fire that when a certain steam pressure is reached, the direct draft will be automatically closed and the check-draft damper opened. The draft regulator is shown in place at D in Fig. 18, and will also be found in Fig. 16. A detailed description of the regulator will be found on pages 60 and 61.

RULE FOR PROPORTIONING RADIATORS

Rules for determining the amount of radiating surface that will be required to satisfactorily heat a building to 70°F. regardless of weather conditions are entirely empirical, that is, they are derived from experience. It is evident that no definite rule can[25] be established that will take into account the method of building construction, the kind and amount of materials that make up the walls and the quality of workmanship employed. These variable quantities coupled with the changing climatic conditions of temperature and wind velocity produce a complication that cannot be overcome in a formula that will give exact results.

Many rules are in use for this purpose, no two of which give exactly the same results when applied to a problem. A common practice is to apply one of the rules in use and then under conditions of exceptional exposure, to add to the amount thus calculated as experience may dictate.

The following rule by Professor R. G. Carpenter of Cornell University was taken from a handbook published by the J. L. Mott Iron Works of New York. This company manufactures and deals in all kinds of apparatus entering into steam and hot-water heating and the rule is given as one that has produced satisfactory results.

Rule.—Add the area of the glass surface in the room to one-quarter of the exposed wall surface, and to this add from one-fifty-fifth to three-fifty-fifths of the cubical contents (one-fifty-fifth for rooms on upper floor, two-fifty-fifths for rooms on first floor and three-fifty-fifths for large halls); then for steam multiply by 0.25, and for hot water by 0.40.

Example.—A room 20 by 12 by 10 feet with glass exposure of 48 feet, ¼ of wall exposure (two sides exposed) 320 feet = 80, ¹⁄₅₅ of 2400 = 44.

48 + 80 + 44 = 172 × 0.25 = 43 feet.
If you add ²⁄₅₅ the surface would be 54 feet.
If you add ³⁄₅₅ the surface would be 65 feet.

PROPORTIONING THE SIZE OF MAINS

For any size system of steam or water heating the following rule will be found entirely satisfactory for mains 100 feet long; for each 100 feet additional use a size larger ratio.

Rule.—

r = (3.1416/d)R = a/r × 100.

r represents ratio of main in inches for each 100 feet of surface; d, diameter of pipe; R, quantity of radiation carried by size of pipe; a, area of pipe in inches.

[26]

From this the following table has been constructed:

FORMS OF RADIATORS

Radiators are much the same in appearance for both steam and hot-water heating. They are hollow cast-iron columns so designed that they may be fastened together in units of any number of sections. The sections are made in size to present a definite number of square feet of outside surface that is spoken of as radiating surface. The amount of radiating surface in any radiator depends on its height and the contour of the cross-section. The radiator sections may be made in the form of a single column as Fig. 22 or they may be divided into two, three, four or more columns to increase their radiating surface.

The following table, taken from a manufacturer’s catalogue, shows the method of rating the heating capacity of a particular design. In the table, the first column gives the number of sections in the radiator, the second column states the length of the radiator in inches. The columns headed heating surface give the heights of the sections in inches and the amount of radiating surface in various radiators of different heights and numbers of sections. As an example: This table refers to the three-column radiators of Fig. 23. Such a radiator 32 inches high with 10[27] sections would contain 45 square feet of radiating surface and would be 25 inches in length.

Fig. 22 is a radiator made up of eight single-column sections.[28] In Fig. 23 is shown five three-column radiators, varying in height from 20 to 45 inches.

The sections of steam radiators are joined together at the bottom with close-nipples, so as to leave an opening from end to end. The sections of hot-water radiators are joined in the same manner, except that there is an opening at both top and bottom. Fig. 30 shows the openings of a hot-water radiator installed as direct-indirect heater. Fig. 24 illustrates a special form of radiator that is intended to be placed under windows and in other places that will not admit the high form. Such a radiator as that shown in the picture is often covered with a window seat and in cold weather becomes the favorite place of the sitting room. Another special form is that of Fig. 25. As a corner radiator this style is much to be preferred to the ordinary method of connection; here the angle is completely filled—there is no open space in the corner.

Wall radiators such as shown in Fig. 26 are made to set close to the wall, where floor space is limited. They are particularly adapted for use in narrow halls, bathrooms and other places where the ordinary type could not be conveniently used.

A radiator that will appeal to all neat housekeepers is that of Fig. 27. It does not stand on the floor as in the case of the[29] ordinary type, but is hung from the wall by concealed brackets. The difficulty of sweeping under this radiator is entirely avoided.

Fig. 28 is a radiator designed to furnish a warming oven for plates and for heating the room at the same time. It is sometimes installed in dining rooms.

The ordinary method of heating by the use of radiators is known as the direct method. The air is heated by coming directly into contact with the radiators and distributed through the room by convection. If the arrangement is such that the air is brought from outdoors and heated by the radiator before entering the room, it is called the indirect method of heating. Such an arrangement is illustrated in Fig. 29. The radiator[30] is located beneath the floor, in a passage that takes the air from outdoors and after being heated, enters the room through a register located in the wall.

Fig. 30 is still another arrangement known as the direct-indirect method of heating. The radiator is placed in position, as for direct heating, but the air supply is taken from outdoors. The radiator base is enclosed and a double damper T regulates the amount of air that comes from the outside. When the inside damper is closed and the outside damper is open, as is shown in the drawing, the air comes from outdoors and is heated as it passes through the radiator on its way to the room. If the dampers are reversed, the air circulates through the radiator as in the case of direct radiation.

In the use of the direct or the direct-indirect method of heating the principal object to be attained is that of ventilation, but quite generally the passages are so arranged that the air may be taken from outdoors or, if desired, the air of the house may be sent through the radiators to be reheated. In extremely cold and windy weather it is sometimes difficult to keep the house at the desired temperature when all of the air supply comes from the outside. Under such conditions the outside air is used only occasionally. In mild weather it is common to use the outdoor air most of the time. The cost of heating, when these methods are used, is higher than by direct radiation, because the air is[31] being constantly changed in temperature from that of the outside to 70°.

The author has stated further that, “It might be said in general that all bronzes reduce the heating effect of the radiator about 25 per cent. while lead paints and enamels give off the same amount of heat as bare iron. The number of coats of paint on the radiator makes no difference. The last coat is always the determining factor in heat transmission.”

PIPE COVERINGS

All hot-water or steam pipes in the basement and in other places not intended to be used for heating should be covered with some form of insulating material. At ordinary working temperature a square foot of hot pipe surface will radiate about 15 B.t.u. of heat per minute. To prevent this loss of heat and the consequent waste of fuel the pipes should be covered with some form of insulating material.

Pipe coverings are made of many kinds of material and some possess insulating properties that may reduce the loss to as low a point as 15 per cent. of the amount radiated by a bare pipe. Many good insulating materials do not give satisfactory results as pipe coverings because they do not keep their shape, some cannot be considered in the average plant because of high cost.

Wood-pulp paper is extensively used as a cheap covering; it is a good insulator and under ordinary conditions makes a satisfactory covering. A more efficient and also a more expensive covering that is extensively used is that made of magnesia carbonate and known as magnesia covering. Aside from these, other forms made of cork, hair-felt, asbestos and composition coverings are sometimes used in house-heating plants.

In selecting a pipe covering, there should be taken into account[33] not only its insulating properties but its ability to resist fire, dampness or breeding places for vermin. It rests entirely with the owner whether he covers the pipes with a combustible or an incombustible material when the insulating properties are about the same. Coverings made of animal or vegetable materials under some conditions furnish a breeding place for vermin.

Pipe coverings are made in sections about 3 feet in length and from 1 to 1³⁄₈ inches in thickness. The sections are usually cut in halves lengthwise to permit being put in place. The sections are covered with common muslin to keep the material in place and sometimes are painted after being installed. Painting has nothing to do with their insulating capabilities, but it preserves the cloth and makes a neat appearance. The sections when put in place are secured by pasting one of the loose edges of the cloth to the surface. The ends of the sections are bound together with strips of metal. Fig. 31 shows the appearance of the pipe when the covering is in place.

Irregular surfaces like the body of the furnace, pipe connections, etc., are insulated by coverings made from a plaster that is made expressly for such work. It is known as asbestus plaster. The plaster may be purchased in bulk and put in place with a trowel. As it is found in the market the plaster requires only the addition of water to put into working form.

The value of a pipe covering is not in proportion to its thickness. Experiments with pipe coverings have shown that a thickness of 1³⁄₈ inches will reduce the radiation 90 per cent., but doubling the thickness reduces the loss only 5 per cent. It, therefore, does not pay to make a covering more than 1³⁄₈ inches thick.

Vapor-system Heating.

—This system of heating is not greatly different from the steam plants already described but it is operated under conditions which do not permit the steam in the[34] boiler to rise beyond a few ounces of pressure. Since the plant is intended to work at a pressure that is scarcely indicated by an ordinary steam gage, it has been termed a vapor system to distinguish it from the pressure systems which employ steam, up to 5 pounds or more to the square inch. The heat is transmitted to the radiators in the same manner as in the pressure systems. The heat of vaporization of steam is somewhat greater at the boiling point of water than at higher pressures, and the lack of pressure, therefore, increases its heating capacity. This is shown in the table, properties of steam, on page 3. The successful operation of such a plant rests in the delivery of the vapor to the radiators at only the slightest pressure and the return of the condensate to the boiler without noise or obstruction to the circulation at the same time ejecting the contained air.

The excellence of the system depends in the greatest measure on good design and the employment of special facilities that allow all water to be discharged from the radiators and returned to the boiler without accumulation at any part of the circulating system. It requires, further, the discharge of the air from the system at atmospheric pressure. The system is, therefore, practically pressureless.

Various systems of vapor heating are sold under the names of their manufacturers. Each possesses special appliances for producing positive circulation that are advocated as features of particular excellence. The vapor system of heating has met with a great deal of favor as a more nearly universal form of heating than either the pressure-steam plant or the hot-water method of heating.

Fig. 31a is a diagram illustrating the C. A. Dunham system of vapor heating. It will be noticed that there are no air vents on the radiators. The air from the radiators is ejected through a special form of trap that is indicated in the drawing. These traps permit the water and air to pass from the radiators but close against the slightly higher temperature of the vapor. This assures the condensation of the vapor in the radiators and excludes it from the return pipes. The water returns to the boiler in much the same manner as in the pressure systems already described but the air escapes through the air eliminator as indicated in the drawing. The system is, therefore, under atmospheric[35] pressure at this point and only a slight amount greater in the boiler.

The water of condensation is returned to the boiler against the vapor pressure, by a force exerted by the column of water in the pipe connecting the air eliminator with the boiler. The main return is placed 24 inches or more above the water line of the boiler. It is the pressure of this column that forces the water into the boiler through the check valve, against the vapor pressure in the boiler.

[36]

It might be imagined that the water in the boiler and that in the air-eliminator pipe formed a “U-tube,” the vapor pressure on the water surface in the boiler, and the atmospheric pressure on the water in the eliminator standpipe. The slight vapor pressure in the boiler is counterbalanced by a column of water in the eliminator pipe. It is this condition that fixes a distance of 24 inches from the water line to the return pipe; that is, the force exerted by a column of water 24 inches high is required to send the water into the boiler.

The vapor pressure is controlled by means of the pressurestat, which is an electrified Bourdon spring pressure gage, connected up by simple wiring to the damper motor, which may be any form of damper regulator. In residential work, the pressurestat is so connected with a thermostat, that both pressure and temperature conditions operate and control this damper regulator, which in turn controls the draft and the fire.

The two instruments are so connected that if the pressure mounts to 8 ounces and the pressurestat caused the draft damper to close and the check to open, the thermostat cannot reverse the damper, regardless of the temperature in the room, until the pressure drops below the limiting 8-ounce pressure. Just so long as the pressure is below 8 ounces, the thermostat is the master in the control of the dampers. The minute that the pressure goes up to 8 ounces then the pressurestat takes control.

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[37]

CHAPTER II
THE HOT-WATER HEATING PLANT

Of the various systems of heating dwellings that by hot-water is considered by many to be the most satisfactory. On account of its high specific heat, water at a temperature much below the boiling point furnishes the heat necessary to keep the temperature of the house at the desired degree. The temperature of the radiators is generally much lower than those heated by steam but the amount of radiating surface is greater than for steam heating plants of the same capacity. It is because of the relatively low temperature at which the water is used, that the greater amount of heating surface is required.

One objection to the use of hot water as a means of heating is, that once the heat of the house is much reduced, the furnace is a long time in raising the temperature to normal. This is due to the fact that the temperature of the water of the entire system must be uniformly raised, because of its continuous passage through the heater. On the other hand, this uniformity of the temperature of the water prevents sudden changes in the temperature of the house. Water-heating plants work with perfect quiet and may be so regulated to suit the outside temperature that the heat of the water will just supply the amount to suit the prevailing conditions.

The care required in the management of the boiler is less than that required in the steam plant because of the fewer appliances necessary for its safe operation. Another advantage in the use of the hot-water plant is its adaptability to the temperature conditions during the chilly weather of early fall and late spring, when a very small amount of heat is required. At such times the temperature of the radiators is but a few degrees warmer than the outside air. The amount of attention necessary for maintaining the proper furnace fire under such conditions is less then for any other form of heating. The increasing use of[38] the hot-water plant for heating the average-sized dwelling attests to its excellence in service.

The Low-pressure Hot-water System.

—A hot-water system consists of a heater, in which the water receives its supply of heat, the circulating pipes for conducting the heated water to and from the radiators that supply heat to the rooms, and the expansion tank that receives the excess of water caused when the temperature is raised from normal to the working degree. In addition to the parts named there are a number of appliances to be described later, that are required to make the system complete.

A hot-water plant of the simplest form is shown in Fig. 32. The illustration presents each of the features mentioned above, as in a working plant. The different parts are shown cut across through the middle, the black portion representing water. Not only does the water fill the entire system but appears in the expansion tank when the plant is cold.

Hot-water heaters are quite generally in the form of internally fired boilers. The fire-box occupies a place inside the boiler and is surrounded, except at the bottom, by the water space. Commonly, these boilers are made of cast iron and are constructed in sections, the same as the steam boiler shown in Fig. 16. Manufacturers sell a single style for either steam or hot-water heating. The boiler in Fig. 32 is cylindrical in form. It is made of wrought iron and contains a large number of vertical tubes through which the heat from the furnace must pass on its way to the chimney.

As the water is heated it expands and rises to the top of the boiler because of its decreased weight. Since the water in the[39] radiator is really a part of the same body of water, the heated portion rises through the supply pipe to the top of the radiator. As the hot water rises in the radiator, it displaces an equal amount of cold water, which enters the boiler at the bottom. This displacement is constant and produces a circulation that begins as soon as the fire is started and varies with the difference in temperature between the hot water leaving the boiler at the top and the cold water entering at the bottom.

As the water in the system is heated and expands, there must be some provision made to receive the enlarging volume. In this arrangement a pipe connects the bottom of the boiler with the expansion tank located at a point above the radiator. Under the conditions represented in the drawing the water does not circulate through the tank and as a consequence the water it contains is always cold.

In raising its temperature, water absorbs more heat than any other fluid and on cooling it gives up an equal amount. As a consequence it furnishes an excellent vehicle for transmitting the heat of the furnace to the rooms to be heated. Water, however, is a poor conductor and receives its heat by coming directly into contact with the hot surfaces of the furnace, and gives it up by direct contact with the radiator walls. To transmit heat rapidly and maintain a high radiator temperature, the circulation of the water in the system must be the best possible. The connecting pipes between the boiler and the radiators must be as direct as circumstances will permit and the amount of radiating surface in each room must be sufficient to easily give up an ample supply of heat. Even though the furnace is able to furnish a plentiful supply of heat to warm the house, it cannot be transmitted to the rooms unless there is sufficient radiating surface. A plant might prove unsatisfactory either because of a furnace too small to furnish the necessary heat or from an insufficient amount of radiating surface. Yet another factor in the design of a plant is that of the conducting pipes. Both the boiler and the radiators might be in the right proportion to produce a good plant, but if the distributing pipes are too small to carry the water required, or the circulation is retarded by many turns and long runs, the plant may fail to give satisfaction.

Fig. 33 shows a complete hot-water plant adapted to a dwelling.[40] It is just such a plant as is commonly installed in the average-sized house but without any of the appliances used for automatic control of temperature. The regulation of the temperature is made entirely by hand, in so governing the fire as to provide the required amount of heat. In the drawing the supply and return pipes may be traced to the radiators as in the case of the simple plant. The supply pipe from the top of the boiler branches into two circuits to provide the water for the two groups of radiators at the right and left side of the house. To provide any radiator with hot water, a pipe is taken from the main supply pipe and passing through the radiator it is brought back and connected with the return pipe which conducts the water back to the boiler.

The expansion tank is located in the bathroom near the ceiling. It is connected with the circulating system by a single pipe which joins the supply pipe as it enters the radiator located in the kitchen. Like the expansion tank in Fig. 31 the water it contains is always cold. It is provided with a gage-glass which shows the level of the water in the tank and an overflow pipe which discharges into the bathtub, in case of an overflow. An overflow pipe must always be provided to take care of the surplus[41] when the water in the system becomes overheated. This does not often occur but the provision must be made for the emergency. The overflow pipe is frequently connected directly with the sewer or discharged at some convenient place in the basement.

The High-pressure Hot-water System.

—In the hot-water plant described the expansion tank is open to the air and the water in the system is subjected to the pressure of the atmosphere alone. The heat of the furnace may be sufficiently great to bring the entire volume of water of the system to the boiling point and cause it to overflow but the temperature of the water cannot rise much above the boiling point due to the pressure of the atmosphere.

If the expansion tank is closed, the pressure generated by the expanding water and the formation of steam will permit the water to reach a much higher temperature. In the table of temperatures and pressures of water on page 3, it will be seen that should the pressure rise to 10 pounds, that is, 10 pounds above the pressure of the atmosphere, the temperature of the water would be very nearly 240°F. (239.4°F.). The difference in heating effect in hot-water heating plants under the two conditions is very marked. In the low-pressure system the temperature of the radiators cannot be above 212° but the high-pressure system set for 10 pounds pressure will heat the radiators to 240°, and a still higher pressure would give a correspondingly higher temperature. The amount of heat radiated by a hot body is in proportion to the difference in temperature between the body and the surrounding air. If we consider the surrounding air at 60° the difference in amount of heat-radiation capacity of the two radiators would be as 180 is to 132. The advantage of the high-pressure system lies in its ability to heat a given space with less radiating surface than the low-pressure system.

In Fig. 34 is illustrated an application of a simple and efficient valve arrangement that converts a low-pressure hot-water system into a high-pressure system without changing in any way the piping or radiators. The drawing shows the boiler and two radiators connected as for a low-pressure system, but attached to the end of the pipe as it enters the expansion tank is a safety valve B and a check valve A, as indicated in the enlarged[42] figure of the valve. The safety valve is intended to allow the water to escape into the expansion tank when the pressure in the system reaches a certain point for which the valve is set. The check valve A permits the water to reënter the system from the tank whenever the pressure is restored to its normal amount.

Suppose that such a system is working as a low-pressure plant. The hot water from the top of the boiler is flowing to the radiators through the supply pipe and the displaced cooler water is returning to the bottom of the boiler through the return pipe as in the other plants described. It is now found that the radiators are not sufficiently large to heat the rooms to the desired degree except when the furnace is fired very heavily. It is always[43] poor economy to keep a very hot fire in any kind of a heater, because a hot fire sends most of its heat up the chimney. If the radiators could be safely raised in temperature, they would, of course, give out more heat and as a result the rooms would be more quickly heated and kept at the required temperature with less effort by the furnace. The difficulty in this case lies solely in there being insufficient radiator surface to supply heat as fast as required.

The increase in radiator temperature is accomplished by the pressure regulating valve B, attached to the end of the pipe as it enters the expansion tank. The expansion tank with the regulating valve is shown enlarged at the left of the figure. The valve B is kept closed by a weight marked W, that is intended to hold back a pressure of say 10 pounds to the square inch. A pressure of 10 pounds will require a temperature of practically 240°F. (see table on page 3). The check valve A is kept closed by the pressure from the inside of the system. When the pressure of the water goes above 10 pounds—or the amount of the weight is intended to hold back—the valve is lifted and an amount of water escapes through the valve B into the tank, sufficient to relieve the pressure. Should enough water be forced out of the system to fill the tank to the top of the overflow pipe, the overflow water is discharged through this pipe into the sink in the basement.

When the house has become thoroughly warmed, the demand for a high radiator temperature is reduced, the furnace drafts are closed, the water in the system cools and as it shrinks the system will not be completely filled. It is then necessary to take back from the tank the water that has been forced out by excess pressure. It is here that the check valve comes into use. So long as there is pressure on the pipes, this valve is held shut and no water can escape, but as the inside pressure is released by the cooling there will come a point where the water in the tank will flow back through the valve A and fill the system.

This is the type of valve used by the Andrews Heating Co. and designated a regurgitating valve. In practice it gives excellent service. The only danger of excessive pressure in the use of this device is the possibility of the valve becoming stuck to the seat through disuse. Any possible danger from such an[44] occurrence may be eliminated by the occasional lifting of the valve by hand.

Heating-plant Design.

—A heating plant should be designed by a person of experience. No set of rules has yet been devised that will meet every condition. Carpenter’s rules given on page 25 serve for hot water as well as for steam as a means of determining the radiating surface required for an ordinary building, but the rules do not take into account the method of construction of the house and the consequent extra radiation demanded for poorly constructed buildings. In many cases the designer must rely on experience as a guide where the rules will not apply. In the case usually encountered, however, the rules given will meet the conditions.

What was said regarding the size of steam boilers required for definite amounts of heating surfaces, applies with equal force to hot-water boilers, because house-heating boilers are commonly used for either steam or hot-water heating. There are no established rules for determining the heating capacities of house-heating boilers. Manufacturers’ ratings are usually low. There are some manufacturers who make honest ratings for their boilers but they are in the minority. When the heating capacity of a boiler is not known from experience, the only safeguard against installing a boiler too small for the radiators to be heated, is to require a guarantee that the plant will give satisfaction when in operation and when considered necessary a certain percentage of the contract price should be withheld until the plant proves itself by actual trial.

Overhead System of Hot-water Heating.

—In Fig. 35 is illustrated another system of high-pressure hot-water heating that corresponds to the overhead system of steam heating. It differs from the high-pressure system already described in the method of distribution and in the radiator connections.

The flow pipe is taken to the attic and there joined to the expansion tank as a point of distribution. On the expansion tank is a safety valve set at 10 or more pounds pressure. The flow of the water is all downward toward the radiators. The circulation through the radiators is also different from the other plants described. The supply pipe joins directly to the return pipe and the connections to the radiators are made at the top and[45] bottom of the same end. The circulation through the radiators in this case is due to the difference in gravitational effect between the hot and colder water at the top and bottom of the radiator. The system requires no air vents on the radiators as all air that might collect in the system goes up to the expansion tank. The safety valve on the expansion tank in this case is the common lever type. The overflow should empty into the sewer and be pitched to prevent any water being retained in the discharge pipe. If water should be retained in this pipe and should freeze, the system would become dangerous, because of the possibility of high pressures from a hot fire.

Expansion Tanks.

—Fig. 36 is a form of expansion tank in common use. It may be used for either the high-or low-pressure system. The body of the tank is made of galvanized iron and is made to stand a considerable amount of pressure. The gage-glass is attached at B, and the overflow at O. The pipe E connects the tank with the circulating system and D connects with the cold-water supply as a convenience for filling the system[46] with water. The object in placing the stop-cock D near the expansion tank is to avoid overflowing the system in filling. The overflow pipe, as stated above, is most conveniently connected with the sewer, into which the water will run in case of an overflow, but the other methods shown are commonly used. There should be no valve in this pipe nor in the pipe E.

The expansion tank must be so located that there will be no danger of freezing. Should it be necessary to place the tank in the attic or where freezing is possible, the tank must be so connected as to become a part of the circulating system. Such an arrangement is shown in Fig. 37. The expansion tank is connected with a supply and return pipe as a radiator. This arrangement is sometimes used but it is not desirable. It is wasteful of heat and there is always a possibility of freezing in case the fire in[47] the furnace is extinguished a sufficient time to allow the water to grow cold.

Any possibility of danger from excessive pressures in either the low-pressure or the high-pressure system must originate in the expansion tank. It is, therefore, desired to again mention the possible causes of danger. Any closed-tank system is liable to become overheated. The expansive force of water is irresistible and unless some means is taken to prevent excessive pressure some part of the apparatus is apt to burst. No closed-tank system should be used without a safety valve.

The low-pressure or open-tank system requires no safety appliances. So long as there is open communication between the tank and the boiler the pressure cannot rise but slightly above that of the atmosphere. There is only one cause that will lead to high pressure in such a system. If the pipe connecting the expansion tank is stopped an excessive pressure might generate. There is little or no danger of this happening.

In the closed-tank system the expansion tank should be of greater capacity than for the open-tank system. Its size is commonly about one-ninth of the volume of water used. The larger tank is necessary to prevent too rapid rise of pressure as the temperature of the water rises. The air in the tank acts as a cushion against which the pressure of the expanding water is exerted.

The extended use of hot-water heating has led to the invention of many appliances for the improvement of the circulation and heating effects. Pulsation valves are used for retaining the water in the boiler until a definite pressure has been attained that will lift the valve long enough to dissipate the pressure. Many of these systems possess merit and some of them are great improvements over the simple plant.

Radiator Connection.

—The method of connecting the radiators to the distributing pipes depends entirely on local conditions. In a well-balanced system any of the methods shown in Figs. 38, 39 or 40 might be used with good heating effects. The method of attaching the supply pipe to the radiator is, however, an important factor in case of accumulation of air. In Fig. 41 is shown the form of connection most commonly used. The drawing is intended to represent a cast-iron radiator with the valve[48] at D, and the air vent at B. Should air collect in the radiator it will rise to the top and displace the water. The water will continue to circulate and heat as much of the radiator as is in contact with the water, but that part not in contact will receive no heat from the water and will, therefore, fail to fulfill its function. As soon as the air vent is opened the air will escape and allow the water to entirely fill the space.

In Fig. 42 a much different condition exists, when air accumulates. In this mode of connection the water enters through the valve V, and escapes at the bottom of the opposite end. When air fills the radiator to the line L, the circulation is stopped and the radiator will grow cold.

[49]

The position of the valve on these radiators is of little consequence. The valve is intended merely to interrupt the flow of the water and may occupy a place on either end of the radiator with the same result.

Hot-water Radiators.

—Radiators for hot-water heating are most commonly of cast iron and in appearance are the same as those used for steam heating. The only difference in the two forms is in the openings between the sections. Those intended for steam have an opening at the bottom joining the sections; while those for hot water have openings at both top and bottom to permit circulation of the water.

Automatic Hot-water Air Vents.

—It is sometimes desired to use automatic air vents on hot-water radiators. For such work a vent is used that remains closed as long as water is present and will open when the water is displaced by the accumulating air, but will again close when the air is discharged. In such vents the valve is controlled by a float, the buoyancy of the float when surrounded by water serving to keep the valve closed. These vents are not so positive in their action as automatic air vents for steam. The change in temperature which controls the steam vent does not take place with hot water. The automatic hot-water vents are not perfectly reliable. They may work with entire satisfaction for a long time and then fail from very slight cause. The failure of a hot-water vent is generally discovered by finding a pool of water on the floor or a wet spot on the ceiling or wall of the floor below.

One type of the automatic hot-water vent that has proven quite successful is shown in Fig. 44. The threaded lug is screwed into the radiator at the proper point. As the water enters the radiator the air is discharged through the vent, escaping at the opening C. When the water has risen to a sufficient height it enters the openings G and H until enough is present to raise the float A. The pointed stem attached closed the hole C with sufficient force to make an air-tight joint. The float A is a very light copper cylinder. Its buoyancy supplies the force to close the vent and its weight opens the vent when the water is displaced by air. It will be readily seen that very slight cause might prevent the performance of its duty.

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[51]

CHAPTER III
THE HOT-AIR FURNACE

Of the methods of heating dwellings other than by stoves, that of the hot-air furnace is the most common. Of the various modes of furnace heating it is the least expensive in first cost and most rapid in effect. In the use of steam heat, the water in the boiler must be vaporized before its heat is available. With hot-water heating, the whole mass of water in the entire system must be raised considerably in temperature before its heat can affect the temperature of the rooms, and consequently in first effect it is very slow. In the use of the hot-air furnace the heat from the register begins to warm the rooms when the fire is started.

Hot-air furnaces are made by manufacturing companies in a great variety of styles and forms to suit purposes of every kind. In practice the furnace is built in sizes, to heat a definite amount of cubical space. The maker designs a furnace to heat a certain number of cubic feet of space contained in a building. It must be sufficiently large to keep the temperature at 70°F. on the coldest nights of winter when the wind is blowing a gale. It is evident that with the variable factors entering the problem, the designer must be a person of experience in order that the furnace meet the requirements.

The following table taken from a manufacturer’s catalogue shows the method of adapting the product of the maker to any size of dwelling. The volume of the house is calculated in cubic feet and from this result the size of furnace most nearly suited is selected from the table.

[52]

CONSTRUCTION

The furnace, in general construction, consists of a cast-iron fire-box with its heating surfaces, through which the flames and heated gases from the fire pass, on the way to the chimney; these with the passages and heating surfaces for heating the air compose the essential features. Fig. 45 shows such a furnace with the sides broken away to show the internal construction. The flames and gases from the fire-box F circulate through the cast-iron drum D and are discharged at C to the chimney. The drum D is made in such form that it presents to the heat from the fire a large amount of heating surface and at the same time offers as little opposition as possible to the furnace draft. The air to be heated enters the furnace through the cold air duct at the bottom, and after circulating through the drum, passes out at the openings R to the conducting pipes. The cast-iron box W is a water tank that should be attached to every hot-air furnace. The water contained in the tank is for humidifying the air as it passes through the furnace. In this furnace the outside casing is of sheet iron, reinforced with wrought-iron flanges. The front, which contains the doors of the fire-box, ash-pit, etc., are of cast iron of ornamented design.

As the air to be heated passes through the furnace it receives part of its warmth by radiation but most of it is absorbed by coming directly into contact with the heating surfaces. Since air is a poor conductor of heat its temperature is raised very slowly;[53] it should, therefore, be kept in contact with the heating surfaces as long as possible to insure an economical furnace. In common practice the ratio of heating surface to grate surface average 35 to 1; that is, for each square foot of grate surface there is 35 square feet of heating surface to warm the passing air. Should this ratio be increased to 50 to 1 the efficiency of the furnace would be much improved.

If the ratio of heating surface to the grate surface is too small for its requirements, the temperature of the air-heating surfaces must be very high to provide the desired amount of heat. Under such a condition the efficiency of the furnace would be low, since in all cases where rapid combustion is required the available amount of heat per pound of coal consumed is low. With a large amount of heating surface, the air remains in contact with the hot surface a relatively longer period and the desired temperature is reached with the expenditure of a smaller amount of fuel. A momentary exposure of the air to a red-hot surface is far less effective than a prolonged contact with a surface having only a moderate temperature. Time is an element of great importance in heating air. In considering the relative merits of two furnaces with the same amount of grate surface, that with the larger amount of heating surface will evidently be the most efficient.

The supply of heat comes primarily from the burning coal on the furnace grate. The grate surface should be large enough in area to permit the required quantity of heat to be generated by the burning fuel with a moderate fire. If the grate surface is too small for the required purpose, a hot fire will be necessary, when the normal amount of heat is demanded by the house. During extremely cold weather, particularly when accompanied by high wind, the extra heat demanded to keep the house at the desired temperature makes necessary the use of an amount of fuel that cannot be burned on the grate unless the fire is forced. Hot fires can be kept up only at the expense of a large amount of heat, and the resultant efficiency of the furnace is reduced.

High furnace temperatures are always attended by a large loss of heat. The vastly greater quantity of air necessary to create the combustion, the high temperature of the chimney gases and the increased velocity of the heated gases through the furnace, all tend to increase the amount of heat that is sent up[54] the chimney, and to decrease the percentage of heat that is delivered by the furnace. In order to heat the house economically the furnace must be large enough to easily generate the required amount of heat demanded in the most severe weather.

Furnace-gas Leaks.

—The presence of furnace gas in the atmosphere of a house is not only annoying but may be a source of danger. Gas leaks are commonly due to the imperfect union of the various parts of which the furnace is composed.

Cast-iron furnaces are constructed in sections that are assembled to form a complete plant. In assembling, the various parts of contact must be carefully joined to prevent the gases in the fire-box from escaping into the air-heating space. In the manufacture of cast-iron furnaces it is practically impossible to form gas-tight joints by the contact of the metal alone. In the erection of the furnace all doubtful joints are filled with stove putty. Furnaces of good design require the use of the least amount of this material.

Stove putty is composed of finely divided graphitic carbon that is made into a paste suitable for filling all imperfect joints. When the putty hardens it withstands the heat to which it is subjected, without shrinking. In the course of time, however, the putty may be displaced and leave openings through which the furnace gases may leak into heating space and thus enter the house. Leaks of the kind may be stopped by renewing the putty which may be obtained from any dealer in stoves.

Location of the Furnace.

—The location of the furnace will generally be governed by the exposure of the house and the location of the chimney. In all exposed rooms on the windward side of the house the temperature will be lower and the air pressure higher than in other parts of the house. The increase in atmospheric pressure makes it necessary to supply to such rooms the hottest air practicable. The conducting pipes, therefore, should be most directly connected with the furnace and with the least run of horizontal pipe. The proper place for the furnace is as near as possible the coldest place of the house.

It is a common practice to place registers near the inner corner of the room, in order to economize in conducting pipe, in horizontal[55] runs. A small amount of economy in first cost is thus secured but the efficiency of the apparatus is sacrificed.

The greatest objection to placing the registers and conducting pipes in the outer walls of buildings is that of loss of heat, due to exposure to the outside cold and the resulting loss in circulation. Losses of this kind may be prevented by covering the ducts with the necessary non-conducting material. The registers should occupy a place in the room nearest the entering cold air.

Flues.

—It is customary to place the conducting pipes for the first floor in such a way as to use only the shortest connections. The flues used for the second floor produce, as in a chimney, a greater velocity of flow to the air and as a consequence larger horizontal pipes are used at the furnace. All horizontal pipes should have upward slant, as much as the basement will permit.

The velocity of the air in the conducting flues will depend on two factors: the height of the flue, and the temperature of the air. To prevent the loss of the temperature of the air, the flue should be covered with at least two layers of asbestus paper bound with wire. Wall flues are commonly flattened and occupy a place in the wall between the studding. Each flue should have a damper at the furnace, that will permit the heat to be shut off from any part of the house.

Rules for proportioning of registers and conducting flues to suit rooms of various sizes are entirely empirical. The sizes of registers and flues found satisfactory in practice is generally a guide for the designer. The following table is taken from a manufacturer’s catalogue and gives a list of sizes that have proven satisfactory under a great variety of conditions and may be taken as good practice:

[56]

The furnace is not only a means of heating the house but may be a means of ventilation as well; to this end it is desirable to arrange the air supply of the furnace to connect with the outside air. This arrangement assures a supply of oxygen even though no special means is arranged for discharging the vitiated air from the rooms.

Combination Hot-air and Hot-water Heater.

—In the case of large houses heated by hot air it is sometimes better to use two or more furnaces than to attempt to carry the heat long distances in the customary pipes. Where heat is required in rooms located at a distance more than 30 feet, it is advisable to use a combination hot-air and hot-water heater, the distant rooms being heated by hot-water radiators.

A furnace arranged for such a combination is shown in Fig. 47.[57] This furnace contains, first, the essential features of a hot-air furnace; next, it includes a hot-water plant. The fire-box and air-heating surfaces are easily recognized. The arrows show the course of the air entering at the bottom of the furnace, which after being heated by passing over the heating surfaces, escapes at the openings marked warm air, to the distributing pipes.

Inside the air-heating surfaces are three hollow cast-iron pieces W, that form a part of the walls of the fire-box. These pieces, with their connecting pipes, form the water-heating part of the furnace, which supplies the hot water for the radiators. The pieces W, with the connecting pipes and radiators, form an independent heating plant, with a fire-box in common with the hot-air furnace.

The returning water from the radiators enters the heating surfaces W, through the pipe marked return pipe. The heated water is discharged from the heaters into that marked flow pipe which conducts it to the radiators. Such a furnace is, therefore, two independent systems, one for hot air and the other for hot water, but with a single fire-box. This furnace, like the simple hot-air furnace, is rated, first in the amount of space it will heat[58] with hot air and in addition, by the number of square feet of hot-water radiating surface that will be kept hot by the hot-water heater.

In Fig. 48 is shown the location of the furnace in a cottage with the conducting pipes to the various rooms. The registers in the first floor are generally set in the floor but if desired they may be placed in the walls. Those on the second floor are placed in the walls because of convenience. The conducting pipes pass through the partitions between the studding.

In all well-arranged hot-air heating plants provision is made so that the air for heating may be taken from the outside. It does not follow that the supply of fresh air should always come from outdoors; there are times during extremely cold weather, accompanied by high winds, when ventilation is ample without the outside source of supply. Since it is never desirable to take the air supply from the basement, such an arrangement as is shown in Fig. 49, or a modification of the same plan is commonly employed. The duct A from the outside and B from the rooms above connect with the air supply for the furnaces. A damper C arranged to move on a hinge, is so placed as to admit the air from either source as desired. The damper may be placed so as to take part or all of the air from the outside by adjusting the handle at the proper place.

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[59]

CHAPTER IV
TEMPERATURE REGULATION

The method used for regulating the temperature of a house will depend on its size, the conditions under which it is to be used and the method of heating. In small houses the temperature may be satisfactorily governed entirely by hand, that is, the furnace drafts may be changed by hand to suit the varying conditions of temperature. A more satisfactory method is that of thermostatic regulation, in which a thermostatic governor and a motor automatically control the furnace dampers so as to keep a constant temperature at one point, generally the living room. Where hot-water or steam heating plants are used, another device is frequently employed to keep the temperature of the heat supply at a constant degree. This is known as the automatic damper regulator. The damper regulator is one of the boiler accessories which so governs the drafts of the furnace as to keep a constant water temperature in the hot-water heater or a constant steam pressure in the steam boiler.

In some cases both the damper regulator and the thermostat are used as a more complete means of temperature control.

Hand Regulation.

—As a means of changing the dampers of the furnace from the floor above, to suit the prevailing conditions, the arrangement shown in Fig. 49 does away with the necessity of a journey to the basement, to remedy each change of temperature.

A plate is fastened to the wall at any convenient place, to which the end of a chain is attached as shown in the figure. This connects with a second chain, the ends of which are fastened, one to the direct draft or ash-pit damper F, and the other to the check draft E, in the chimney. As the furnace appears in the drawing, the direct draft is closed and the check draft is open. By changing the ring from G to H, the movement of the chain opens F, and closes E, admitting air to the furnace. When the[60] temperature of the room is raised sufficiently, the drafts are restored to their original position by replacing the ring at G. Sometimes one or more intermediate points are made on the plate between G and H, which permits both drafts to be kept partly open and fewer changes are required to keep the temperature approximately normal.

Damper Regulators for Hot-water Furnaces.

—The damper regulator for a hot-water boiler automatically controls the dampers of the furnace so as to keep the water of the boiler approximately at a constant temperature. The regulator is shown in Fig. 52. The ends of the lever are connected to the direct-draft and check-draft dampers, as in the case of the damper regulator for the steam plant. A cross-section of the working parts shows the details of construction. The lever d is operated by a diaphragm g, which tightly covers a brass bowl, containing a mixture of alcohol and water, of such proportions as will produce a vapor pressure at the desired temperature, say 200°. The hot water from the boiler passes through the valve, entering at a and leaving at b. When the water reaches the desired temperature, the contained liquid vaporizes and a pressure is produced that is sufficient to lift the diaphragm and the lever. The chain attached to the right-hand end closes the direct-draft damper; at the same time the other end of the lever opens the check draft, and the supply of air to the furnace fire is entirely cut off. As soon as the water has cooled sufficiently,[62] the vapor pressure in the bowl is reduced, allowing the weight W to depress the diaphragm and the lever is restored to its first position. The weight W is for adjusting the valve to the desired temperature. The plug f tightly closes the orifice through which the liquid is introduced into the bowl.

The object of the damper regulator on a hot-water boiler is to govern the fire of the furnace so as to keep the water in the boiler at the desired temperature. In case there is a demand for heat at any part of the house, a supply of hot water will always be on hand. It has nothing to do with the regulation of the temperature of the house. The control of the house temperature is the office of the thermostat.

The thermostat is a mechanical device for automatically regulating temperature. It may be arranged to operate the valve of a single radiator or register and so control the temperature of a room, or as commonly used in the average dwelling, the controller may be placed to govern the temperature of the living room and in so doing keep the furnace in condition to satisfactorily heat the remainder of the house.

Thermostats are made in a variety of forms by different manufacturers but they may be divided into two general classes: the electric, and the pneumatic types. The electric thermostat depends on an electric current as a means of controlling the action of the motor which in turn operates the furnace dampers so as to maintain a constant heat supply. The pneumatic thermostat regulates the supply of heat by means of pneumatic valves. It will be considered later in discussing mechanical ventilation. This type of temperature regulation is particularly adapted to large buildings.

Fig. 53 illustrates one style of electric thermostat that is very generally used for temperature regulation in the average dwelling. It consists of three distinct parts—the controller, the electric battery and the motor. In the drawing the motor is shown connected with a steam valve, such as may be used for furnishing steam for a series of radiators. It may with equal facility be attached to the dampers of a furnace or other heating apparatus.

The controller occupies a place on the wall of the room to be heated and makes electric connections between the battery and the motor. Whenever the temperature varies from the required[63] degree, a change of electric contact in the controller starts the motor, and the radiator valve or the furnace drafts are opened or closed as occasion requires.

The controller appears in Fig. 54 as commonly seen in use. The upper part carries a thermometer and the pointer A indicates the temperature to be maintained in the room. The middle division indicates 70°F. Each division to the right of the middle point raises the temperature 5°. Each division to the left lowers the temperature a like amount.

In addition to the ordinary type this controller is furnished with a time attachment by means of which the controller may permit the temperature of the room to fall to any desired degree at night and raise it again in the morning at the time for which it is set.

This is accomplished by a little alarm clock shown at the bottom of the controller in Fig. 54. The indicator B is arranged to correspond with the indicator A; the middle point representing 70°F. To set the time attachment, the alarm is wound and set as in any alarm clock, ½ hour earlier than the desired time for rising. The indicator B is set for the day temperature and A is set for the temperature desired during the night. At the appointed time the alarm moves the indicator A to the desired point for the day and the controller raises the temperature accordingly.

Fig. 55 shows the mechanism that is exposed to view when the cover of the controller is removed. The bent strip C is the part that is influenced by the change of temperature. It is made of two thin strips of metal, one of brass and the other of steel. The two strips are soldered firmly together. Any change in temperature will affect the strip and cause it to bend and touch the contact point—K or J. The bending of the strip is due to the unequal expansion of the brass and steel due to the change of temperature. Brass expands 2.4 times as much as steel with the same change of temperature. The amount of bending is sufficient to make an appreciable movement in a small fraction of a degree change. The brass part of C is on the left and since it expands the greater amount, a rising temperature causes C to come into contact with the point J. When this happens the motor is started and makes one-half cycle. In so[64] doing it shuts off the air supply of the furnace, opens the check draft and at the same time the motor changes the electric contact from J to K. When the temperature begins to fall, the brass contracts in the same ratio to the steel as it expands during the rising temperature and as a consequence the bar bends to the left. When the strip touches the point K the motor again makes one-half circle, admitting air once more to the furnace, closes the check draft and shifts the electric contact back to K. When properly started the thermostat will regulate the temperature within a degree of temperature.

The Thermostat Motor.

—The thermostat motor automatically opens and closes the furnace dampers or the valve that admits steam to the radiators as heat is demanded by the controller.

The motor, as shown in Fig. 53, consists of a system of gears and a brake S, which regulates the speed, a cam M, and armature I, for starting and stopping the motor, and the electromagnet H-H which operates the bar I. Two lever arms L, one in front and the other at the back of the motor furnish means for attachment to the valve or furnace dampers. An emergency switch at D is shown in detail in Fig. 56. The battery B furnishes the current which energizes the magnets and an iron weight supplies the motive power for the motor.

The description of the operation of the motor applies to the steam valve shown in Fig. 53. The same motor might be used for opening and closing of the dampers of the furnace in any kind of heat supply. The method of communicating the motion of the motor arms to the dampers of the furnace will be described later. The connections with the furnace drafts are shown in Figs. 3, 6, 8, 34, etc.

Suppose that the valve for admitting steam to the radiators, as that in Fig. 53, is closed and that the temperature of the house is falling. The strip C of the thermostat controller is moving toward J. When contact is made, the current from the battery B energizes the magnets H-H and the bar I is lifted. As the bar I is raised the catch J is released and permits the motor to start. The bar I is held suspended by the cam M until the arm L has made one-half revolution, when the lug K drops into the depression in the cam made to receive it and the catch J engages with the brake and stops the motor.

[65]

[66]

During this movement the arm L has lifted the valve arm N and the valve admits steam to the radiators, at the same time the contact M has been shifted from the right-hand contact to the left, and the electric circuit is ready to be made in the controller at the point K. When the temperature has fallen a sufficient amount the controller bar C will make contact at K and the motor will again make a half cycle, changing the valve back to its original position. This process will be kept up so long as the motor is wound and there is sufficient fuel in the furnace to raise the temperature.

Fig. 55 shows the method of connecting the electric wires from the battery to the controller. A three-wire cable connects the battery, and makes contacts as indicated at H, K and J. The wires are shown attached to the motor as in Fig. 55. A wire is taken from either pole of the battery and attached to one of the ends of the magnet coil. Passing through the magnet the wire is attached to the frame of the motor. This makes the cam M a part of the electric circuit. The other two wires are attached to the brass strips on each side of the arm L. The strips are insulated from the frame. The electric circuit through the magnet is made alternately by contact with the strips at right and left of the arm L.

In case the motor, through neglect, runs down, a safety switch at D (Fig. 53) disconnects the battery and keeps it from being discharged. This switch is shown in detail in Fig. 56. When the weight has reached its limit, the piece C on the chain comes into contact with D and lifting it out of contact, breaks the circuit. When the motor is again wound, C engages with E and restores the contact. The switch is so arranged that when open, the valve will always be closed.

[67]

In Fig. 2 is shown such a combination attached to a boiler. The cord from the regulator, instead of extending directly to the direct-draft damper, passes over the pulley P and connects to the thermostat cord. The regulator may now close the damper to suit the steam pressure, but after the temperature in the rooms is normal, the amount of heat necessary to maintain the desired degree is regulated entirely by the thermostat which opens and closes the dampers regardless of the position of the damper regulator.

If occasion should require but a very slight amount of steam to keep the house at the desired temperature, the thermostat will govern the drafts aright. If the steam pressure is in danger of becoming excessive, the damper regulator will govern the drafts.

Thermostat-motor Connections.

—The arrangement of cords and pulleys used for attaching the thermostat motor to the furnace dampers will depend very much on local conditions. The motor can be placed in any convenient position so that the connecting cords will act most directly. The motor opens and closes the direct draft and check draft in accordance with the demand for heat. The connections for all kinds of furnaces are made in much the same manner. The pulleys supplied with the motor are placed to work as freely, and the cords to pull as directly as possible.

In Fig. 57 the motor is connected with a hot-air furnace. The cord D is attached to the front arm of the motor and connects with the direct-draft damper F. The cord C connects the rear arm of the motor with the check-draft damper at E. In the position of the dampers shown, the direct-draft damper is closed[69] and the air is entering the chimney through the check draft E. While this damper is open there is very little induced draft to supply the fire with air that might leak through the crevices around the ash-pit door, but the gases from the furnace are completely carried away to the chimney by the air entering at E.

In Figs. 3, 6, 8, 34, etc., the same motor is connected with the furnaces of various other systems of heating. The object is the same in all; when less heat is required, the air supply is cut off and the furnace fire subsides; when more heat is demanded the air is again admitted to produce greater combustion. The check draft is an important feature as it checks the flow of air through the furnace regardless of the position of the direct-draft damper. Even should the direct draft be left open, the check draft when open would destroy in a great measure the supply of air entering the furnace.

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[70]

CHAPTER V
MANAGEMENT OF HEATING PLANTS

The following instructions on the care and management of steam and hot-water heating plants is printed with permission of the American Radiator Co. They were prepared as a guide to the successful operation of the Ideal heating plants but apply with equal force to other plants of a similar character.

General Advice.

—No set rules can be given for caring for every boiler alike—chimney flues are not alike—some have strong draft, some are average and some are weak. There is much more difference in the heat-making qualities of coal than is commonly known, and it is important that the right size coal for the draft be used. These rules apply to most all fuels. A little trying of this way or that way of leaving the dampers (when regulators are not used) often discovers the better way. It is well to vary from the rules a little if any of them do not seem to bring about the best results.

With good, average chimney flue draft and the right kind of fuel, these rules will govern the large majority of cases.

The Economy of Good Draft.

—In many cases a boiler with sluggish draft will burn more coal than a boiler with good draft. In the first case the fuel may be said to “rot”—in lacking air supply the gases pass off unburned. The “nagging” which a boiler has to take under these conditions increases the waste of fuel. A boiler under sharp, strong draft maintains a clear intense fire and burns the gases—getting the larger amount of heat from the coal.

1. Put but little coal on a low fire.

2. When adding coal to the boiler, open the smoke-pipe damper (inside the smoke pipe) and close the cold-air check damper. This will make a draft through the feed doorway inward and prevent the escape of dust or gas into the cellar when the feed door is open to take fuel. Put these parts back to their regular places after feeding.

[71]

3. When it can be done, in feeding a large amount of coal (as for night) leave a part of the fire or flame exposed, so that the gases may be burned as they arise.

4. When a regulator is not used, learn to use the dampers correctly and according to the force of the chimney draft. Learn to use cold-air check damper. Often, when closing, the ash-pit draft damper does not check the fire enough; opening the cold-air check damper will check it about right. Increasing or lessening the pressure of a steam boiler must be done by changing the weight on the regulator bar.

5. Carry a deep fire or a high fire; let the live coals come up to the feed door—even in mild weather when from 4 to 6 inches of ashes stand on the grate.

6. In severe weather give the heater the most careful attention the last thing at night.

[72]

7. Do not overshake or poke the fire in mild weather; once in a while shake enough to give place for a little more fuel.

8. Do not let ashes bank up under the grate in ash-pit. Grate bars are very hardy, but it is possible to warp them with carelessness. Taking up the ashes once a day is the best rule, even if but little has fallen into the pit.

9. Keep the boiler surfaces and flues clean; a crust of soot ¼ inch in thickness causes the boiler to require half as much more fuel than when the surfaces are clean.

10. If convenient, have a water hose to spray the ashes when cleaning out the pit.

11. Attend the boiler from two to four times per day. In mild weather, running with a checked fire, morning and night is usually often enough. In severe weather, once in early morning, again at mid-day, again at five or six o’clock and finally thorough attention at from nine to eleven o’clock in the evening.

12. If, through burning poor coal, the fire pot gets full of ashes, or slate and clinkers massed together, the quickest way to get a good active fire is to dump the grate and then build a new fire—from the kindling up.

13. If a hard clinker lodges between the grate bars, do not force the shaking, but first dislodge the mass with a poker or slicing bar. Then the grate will operate without damage.

Weather and Time of Day.

—In severe weather keep the fire pot full of coal, and run the heater by the dampers or regulator (if one is used). Thoroughly clean the grate twice a day. Let the top of the fire in front be level with the feed door sill. Bank up the coal higher to the rear.

In moderate weather there should be from 2 to 6 inches of ashes between the live coal and the grate. As the weather grows colder keep the grate and the fire pot a little cleaner—sometimes it helps to run the poker or slicing bar over it through the clinker door. With some fuels this is never necessary.

Night Firing.

—In very cold weather, when the house should be kept warm all night, clean the grate well at a late hour—the last thing. Clear the bottom of the fire pot of all ashes and clinkers so that the grate is covered with clear-burning, red-hot coals, then fill the pot full of fuel. If possible, leave some of the flame exposed to burn the gases. Leave the drafts on long enough to burn off some of the gas, then check the heater for the night.[73] Thus there is plenty of coal to burn during the night and some on which to commence early in the morning. Some drafts do not make it necessary to leave the dampers on to burn off the gas after feeding.

With the ash-pit draft damper closed and the cold-air check damper open at night, but part of the coal is burned and there is much of it not burned in the morning. So, by reversing the dampers in the early morning the fire starts up quickly and often the house may be well warmed before any coal is put into the fire pot.

Some boilers are run the other way—a very poor way. If the grate is cleared off in very cold weather and coal added at five or six o’clock in the afternoon, by eleven o’clock at night nearly one-half of the coal is burned and the grate is covered over with a mass of ashes and clinkers. With little coal remaining, to shake the grate will quite likely put out the remaining fire; to put fresh coal on a low fire reduces further its declining temperature. The result is a cold house that will grow colder until a new fire is started.

Often in cold weather with this poor way of night firing, it takes one or more hours of forced firing to warm the house in the morning, and all the coal saved the night before is more than used to get the house or building “heated up”—while the people who should be comfortable have to get up, bathe and take breakfast in chilly rooms. At no time in the day is heat more wanted than about the time of getting up and starting the day. A fire well cared for late in the evening makes a warm house all night. And so it follows that it is much easier to add a little more heat in the morning. And surely less coal is burned, for the forcing of a fire part of the time often overheats, and wastes coal.

First-day Firing.

—In the morning of moderate winter weather, with the ash-pit draft damper open, before adding any coal allow the fire to brighten up if it seems to be low; then (for such conditions) spread over a thin layer of fresh coal and set the drafts for a brisk fire. After the new fire is well started add as much coal as may be necessary to last until next firing. Do not shake much if any—just enough to give space for more coal. Then by setting the regulator (if one is used), or, by closing the ash-pit[74] draft damper and opening the cold-air check damper a little, the boiler should keep up its work until the next firing time.

In severe weather, if the boiler has been attended to at night as directed in the section on “night firing,” the drafts can be turned on and the boiler run for half an hour before adding coal. Or, if more convenient to give it immediate attention, the grate can be thoroughly shaken and enough coal added to last until mid-day. Often the cold-air check damper will need to be entirely closed and the ash-pit draft damper partly open if the heater is a water boiler. If a steam boiler, the regulator should then be set to maintain the number of pounds of pressure wanted and so left.

Other-day Firing.

—In severe weather more coal should be added about noon, sometimes the draft may be left on for a few minutes and then checked. And in such weather it is often well to give the boiler further attention at five or six o’clock. In severest weather the boiler should not be attended more than four times a day; and generally not less than three times.

Often much coal is wasted by “nagging” the fire—poking, shaking and feeding it until it becomes “dyspeptic.” A sure cure is a little common sense in regular feeding, etc.

Economy and Fuels.

—In running many boilers for moderate weather better results follow if the grate is not shaken too much or too often. Sometimes in moderate weather a body of ashes on the grate checks the fire and there is enough heat without a useless burning of fuel. Many houses are overheated in moderate weather and too much coal burned by running the boiler as for zero weather.

So we repeat—it is not wise to overshake or overfeed a boiler in moderate weather. The fire should be in such shape that if a change comes at night there is a basis for a good fire to start on. When the grate is shaken but once during the 24 hours (during moderate weather) late at night is the best time.

When one stops to think that heating is needed during about 7 months out of the year, and that a greater portion of this time is usually moderate weather when a very little heat is needed, it must be seen that the science of running the heater to save coal is to apply common sense rules of limiting the feeding and the attention in such periods. In severe weather we believe in giving the boiler a liberal quantity of fuel regularly and at the right[75] time. The time to save coal is when there is no need for burning it. This is where a great many people make errors in running the boiler—in forgetting to “let up” on the shaking and feeding in moderate weather.

With some drafts and for boilers using hard coal or coke, good economical results often are secured by opening the feed door a little when it is desired to check the fire in moderate weather. This depends on the draft.

For Burning Soft Coal.

—Some types of boilers are made to burn soft coal with economy, with least work. Some types are made specially to burn the meaner grades of soft coal. Firing to prevent smoke is a source of economy and these ways of running should be followed—specially with large sectional boilers.

There are two types of soft coal, viz.: The free-burning coal, which breaks apart when burning, allowing the gases to freely escape; and the fusing-coking coal, which, when burning, first fuses into a solid burning mass with a hard crust over the top, slowly coking as it burns. The latter kind is most valuable for house-heating boilers because the gases are more thoroughly consumed. The fusing-coking coal is worth about 20 per cent. more for this purpose than the free-burning coal.

The gases should be allowed to pass off from the coal slowly. Leave air inlet on the feed door open if draft permits. If possible, use uniform sizes of coal. Avoid using coal having too much dust—the “run-of-the-mine” may be lower in price but its heat-making value is also low.

For the purpose of slow burning of soft coal, it is well in feeding at night to let the fire burn up freely so that the coals are very live with heat. Then fill in enough coal to last all night—leaving some of the live coals uncovered if possible. With large sectional boilers this exposure should be at the rear of the fire so that the flame will pass over the live coals. Thus the gases coming off from the fresh coal are burned and a larger amount of the full heat-producing value of soft coal is made use of and with less smoke.

After a boiler is so fed, the dampers (unless an automatic regulator is used) should be left about as follows:

Ash-pit draft damper open a little or closed, as draft may require.

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Cold-air check damper open about one-eighth to one-third distance of the opening.

Smoke-pipe damper about one-half closed.

A little experiment with the draft will usually tell the operator the best way of leaving these dampers.

It will be found in the morning that the entire charge of coal is well burned or partly coked.

The coked fuel, or that which sticks together in a mass, should be broken up by the poker and more added generally as by rules given in other sections.

It must always be remembered that the soft coals mined in different parts of the country have widely varying heat-making capacities. To obtain satisfactory results brands must be selected which have an established reputation for excelling results in small boilers.

For Burning Coke.

—It is best to keep the pot full of fuel—keeping a large body of coke under a low fire rather than a little fuel under a strong fire.

It must be remembered that coke makes a very “hot fire” because the coke is free-burning. Care should be taken not to leave drafts on too long in boilers not having regulators.

Coke burns best for house-heating purposes with less draft than is required for coal, therefore to keep a low fire the ash-pit draft damper should be kept closed, and the smoke-pipe damper almost entirely closed. The regulator (when used) can be set to keep the dampers about as here advised. Coke is practically smokeless and its quick-burning character makes a cut-off damper in the smoke pipe (which will stay fixed as it may be set) quite necessary.

It is well to keep a layer of ashes on the grates and when shaking stop before red-hot coals come through the grate. The coke then burns more slowly, which increases its effectiveness.

With some drafts it may be well to “bank the fire” at night with coke—pea coal size. This is a matter of experiment, and depends on the character of the chimney draft.

Fire should be tended regularly—two times a day, or four at the outside.

With an extra strong draft, at night the fuel should be packed down by tamping with the back of a shovel.

[77]

With ordinary condition of draft, crushed coke, small egg size, should be used.

Other Rules for Water Boilers

—To Fill System.—Open the feed-cock when the heater is connected with a city or town water supply; if not, fill by funnel at the expansion tank. Fill until the gage-glass on the expansion tank shows about half full of water. In filling the system see that all air cocks on the radiators are closed. Then beginning with the lower floor, open the air cocks on each radiator, one at a time, until each radiator is filled; then close the air cock and take the next radiators on upper floors until all are filled, after which let the water run until it shows in the gage-glass of the water tank. After the water is heated and in circulation, vent the radiators by opening the air valves as before. Then again allow the water to run into the system until it rises to the proper level in the expansion tank gage-glass.

Always keep the apparatus full of water unless the building be vacated during the winter months, when the water should be drawn off to prevent freezing. Never draw water off with fire in the heater.

To draw off water, open the draw-off cock at the lowest point in the system, and then open air cocks on all radiators as fast as the water lowers beginning with the highest radiator.

Air-vent Valves on Radiators.

—In order to secure the full benefit of the heating surface of a hot-water radiator, the inside of the section must be free of air. When a radiator is “air-bound” it means that parts of the sections are filled with air in pockets which remain until the air is allowed to pass off through the vent valve.

Air will gather from time to time at the highest points inside the radiators, especially in those placed in the upper stories of the building. These air accumulations inside cut down the working power of a radiator exactly in proportion as they rob the inside of the casting of proper contact with heated water. Air pockets not only reduce effective heating surface, but they also prevent the circulation of hot water.

Therefore, it is well once in a while to take the little key provided by the heating contractor and open the air valves on radiators to allow the air (if any) to escape. When a radiator does not work as well as usual, open the air valves until the water[78] flows, which indicates that the air has been fully released. Then close the valve.

Valves on Cellar Mains.

—If cut-off valves have been placed on the main and return pipes in the cellar, see that the valves on one line of main and return pipes (at least) are open when the boiler is under operation. Be sure that the system is open to circulate water through the supply and return pipes before building a fire in the boiler.

It is a very good idea to take down the smoke pipe in the spring, thoroughly clean and put it back in place. Leave all doors open on the boiler in the summer time.

Other Rules for Steam Boilers

—To Fill Boiler.—Open the feed-cock when the heater is connected with city or town water supply; if not, fill through the funnel. Let the water run until the gage-glass shows about half full of water.

In the first filling, after the water has boiled, get up a pressure of at least 10 pounds, draw the fire and blow off the boiler under pressure through draw-off cock to remove oil and sediment, after which refill with fresh water to the water line. This is best done usually by the steam-fitter.

The damper regulator will control the pressure of steam, closing the damper when the pressure is raised beyond the desired point and opening the damper when the pressure falls below that point. By removing the weight on the lever, different degrees of pressure can be kept up. The regulator should be allowed to control the drafts without interference.

Examine the water glass often to see that the water line is at the proper height. If lower than normal open the supply pipe until the water runs in and stands at the proper level. It is best when no water stands in the glass, nor shows at the bottom of the try-cock, to quickly dump the grate and do not put water into the boiler again until it is cooled off.

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If there is one or more shut-off valves on the main or return pipes, before starting a fire see that one line of piping at least (main and return) is open to circulate the steam.

To Control Radiators.

—When it is desired to shut off steam from any radiator (if the regular radiator valves are used), close the valve tight, and when it is turned on see that the valve is wide open. A valve partly turned off will cause the radiator to fill with water. This rule applies only to one-pipe heating systems.

If “automatic” air valves are used they must be carefully adjusted by the steam-fitter and then left to operate without undue interference.

End of the Season.

—At the close of the heating season fill the steam boiler with water to the safety valve and let it thus stand through the summer.

Also thoroughly clean all the fire and flue surfaces of the boiler and at the opening of the next season withdraw the water and refill with fresh water to the water line, starting the boiler as before.

It is advisable to have a competent steam-fitter blow off the boiler under pressure and thus give the inside a thorough cleaning when the boiler is first set up and ready for fire.

A low-pressure boiler, using good water, rarely needs blowing off after it is once cleaned at time of setting up.

THE RIGHT CHIMNEY FLUE

The area of the flue should never be less than 8 inches in diameter if round, or 8 by 8 inches if square—unless for a very small heating boiler or tank heater. Nine or 10 inches round, or 8 by 12 rectangular is a good average size. The flue should generally have a little more area than that of the connecting smoke pipes.

Draft force depends very much on the height of the flue.

The chimney top should run above the highest part of the roof[80] and should be so located with reference to any higher buildings nearby that the prevailing wind currents will not form eddies which will force the air downward in the shaft. Often a shifting cowl which will always turn the outlet away from the source of adverse currents will promote better draft.

The flue should run as nearly straight up from the base to the top outlet as possible. It should have no other openings into it but the boiler smoke pipe. Sharp bends and offsets in the flue will often reduce the area and choke the draft. The flue must be free of any feature which prevents a free area for the passage of smoke. The outlet must not be capped with any device which makes the area of the outlet less than the area of the flue.

The best form of flue is a round tile—in such there is less friction than in the square form and the spiral ascent of the draft moves in the easiest and most natural manner.

If the flue is made of brick only, the stack should be at least two 4-inch courses in thickness.

If there is a soot pocket in the flue below the smoke-pipe opening, the clean-out door should always be closed. If this soot pocket has other openings in it—from fireplaces or other connections—such arrangements are very liable to check the draft and prevent best action in the boiler.

The smoke pipe should not extend into the flue beyond the inside surface of the flue, otherwise the end of the pipe cuts down the area of the flue and injures its drawing capacity.

The inside of a flue should be smooth (pointed or plastered). When the courses are laid with the mortar bulging out from the joints the friction within the flue is very much increased. Often a troublesome flue is corrected by lowering some sharp-edged weight by a rope which should be worked against the sides of the flue until the clogging is scraped off.

A new chimney when “green” will not have a good drawing capacity. Short use dries out the mortar and better results follow.

“Smokey” Chimneys.

—The failure of draft in flues may be due to a variety of causes, one of which is illustrated in Fig. 57b. The short chimney on the left side of the roof shows the course of the wind as it passes over the ridge of the roof and why the draft in such a chimney is retarded whenever this condition exists.[81] The force of the wind, as it comes into contact with the roof, causes a compression of the air on the windward side and a rarification on the lee side. This inequality of pressure causes a downward sweep of the wind as indicated by the arrows. The effect on the low chimney is to retard the draft and sometimes the pressure is great enough to reverse the action of the flue and force the smoke into the house. The only remedy for such a condition is an extension of the chimney that will raise its top above the ridge.

The same effect is often produced by a neighboring building or a border of trees that are higher than the chimney and dense enough to effect the wind pressure.

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CHAPTER VI
PLUMBING

The term plumbing is usually understood to cover all piping and fixtures that carry water into the house and remove the waste material in the form of sewage. It does not include the pipes of the heating system. Although the work of installing heating plants is frequently done by plumbers, pipe fitting and plumbing are two distinct trades.

In the process of building a house the rough plumbing is put into place as soon as the structure is enclosed and the rough floors are laid. The rough plumbing includes the soil pipe, into which the waste pipes from the various fixtures empty, and those pipes which must occupy a position inside the partition walls and beneath the floors.

The connections here described are for a city dwelling and apply to the custom of local conditions. The same system might be used for a country residence except in regard to the water supply and method of sewage disposal. Plants of this type are discussed in the chapter on septic tanks.

Fig. 58 shows a cross-section of the street, exposing the sewer S, the water main W, and the connections with the house. The side of the house has been removed to permit a view of the water and sewer pipes, connecting with the bathroom, kitchen, laundry and other basement fixtures.

The lateral sewer or house drain, which connects the house with the street sewer S, is provided with a trap G, located, in this case, just outside the basement wall. The house drain is made of vitrified tile, laid so as to grade into the street sewer with the greatest possible pitch. The sections are laid as true as conditions will permit and the joints are all carefully filled with cement mortar to prevent leakage. The object of the trap G is to prevent sewer gas from entering the house from the main sewer. The trap prevents the gas from passing because the water in the bend[83] of the trap forms a water seal, beyond which the polluted air from the sewer cannot travel.

Next inside the trap is the vent pipe E, that extends to the surface of the ground. In this case it is just outside the basement[84] wall. The top is covered with a metal cap. Another arrangement often made to accomplish the same purpose is shown in Figs. 61 and 62, where a piece of soil pipe in the form of a bend is made to take the place of the cap. Inside the basement and extending up through the partition walls to the roof is the waste stack or soil pipe A. This pipe as is explained in detail later, is made of cast iron and is put together with calked lead joints. The top of the stack at the point where it passes through the roof is shown in Fig. 59. In extending through the roof the pipe A must make a water-tight joint to prevent water from leaking through. This is accomplished by means of the metal plate D, which is set under the shingles and the piece C, that is soldered to D. The joint between C and A is best made with lead the same as the other joints of the stack. In the case of very high stacks, the bottom should be supported by a pier or iron pipe rest. Besides being supported at the base the stack should be secured to the side walls or floor beams at each floor. This is to keep the pipe from moving out of place and the consequent opening of joints.

All of the waste pipes from the bathroom, kitchen and basement drain into the waste stack. The cellar drain for draining the basement is shown at T in Fig. 58. It also appears in detail in Fig. 60. The plate B, in the latter figure, is set flush to the surface of a depression in the floor that serves as a collecting point for water. The floor is constructed to drain toward this point. The plate is perforated to let the water through and is generally hinged so that in case of stoppage the cover may be raised. The bell-shaped piece under the cover surrounds the piece C, to form a water seal when the level of the water is at A.[85] In addition to this water seal there is generally a trap between the drain and the sewer as shown in the drawing.

The method of connecting the bathroom waste pipes with the stack is shown in Fig. 99 and will be described later. All of the sewage of the house is emptied into the stack by the most direct route, and from the stack it is conducted as directly as possible into the sewer. From the drawing it will be seen that all openings to the sewer are sealed in two separate places, once at the outlet to prevent the air from the street sewer entering the house drain G, and again at each opening to prevent escape of the sewer gas from the drain into the house.

The openings at E and A at each end of the stack permit a constant circulation of air for ventilation. The length of the stack and its location causes it to act as a chimney and the draught produced takes the air in at E, and discharges it at the top. In large houses there is sometimes added a vent stack to produce further ventilation, but in the average dwelling the arrangement here shown covers the common practice.

In Figs. 61 and 62 are shown in detail two methods of arranging the sewer connections in the basement to permit of the removal of obstructions in case the pipes at any time become stopped. The trap, vent, etc., are easily recognized. With the arrangement as shown in Fig. 62, the clean-out is so placed as to give access to the inside of the pipe. Should an accumulation or obstruction of any kind become lodged in the pipe, the stop in the clean-out[86] is removed and a flexible metal rod is used to remove the stoppage. The trap outside the wall has an opening through which the obstruction may be reached in case it cannot be removed from the first clean-out. The disadvantage in using the outside trap, as here shown, is that it can be reached only by excavation.

Fig. 61 shows another common method of installation. Here the trap is placed inside the basement wall. This gives an easier means of opening the trap than Fig. 62 affords and accomplishes the same purpose. The connections with the stack are the same as in Fig. 62. Obstructions in the sewer pipe are most likely to become lodged in the trap and for this reason the trap should occupy a position that is reasonably easy of access.

The outside trap as described above is quite generally installed in buildings of all kinds, but its use is by no means universal. In some communities it is not used at all, and many plumbers consider it only an added means of causing stoppage and an extra expense to install.

The object of the outside trap is to keep the air of the street sewer from entering the house drain. It is at once inferred that the air of the street sewer is more dangerous than that of the house drain. The street sewers, however, are ventilated at each street corner and at each manhole. There cannot then be much difference in the air of the two places. The traps on the fixtures that prevent sewer gas from entering the house would be just as efficient if the outside trap did not exist.

While the methods shown in Figs. 61 and 62 are considered good practice, there is considerable objection to the vent being placed near the dwelling, because of the sewer gas that is forced out, whenever a sudden discharge of water goes into the drain. Each time a closet is flushed, a large volume of water enters the stack and completely fills the pipe. When this occurs, the descending water forces out the air of the pipe ahead of it, and a gush of offensive air filled with sewer gases is forced out of the vent. It is evident that such a vent, located near an open window or where it will reach the nostrils of the inhabitants is a thing not greatly to be desired.

Outside traps when placed near the surface sometimes freeze.[87] The circulation of air through the vent is occasionally sufficient in cold weather to freeze the water and stop the trap.

Water Supply.

—The water supply taken from the street main is conducted to the house by the pipe shown in Fig. 58, at C. This pipe is generally of lead as piping of that metal is the most durable for underground work. Iron used under the same conditions will last only a few years. The connection is made with the water main by use of a corporation cock. This is a special style of cock that is shown in Fig. 63. In the figure the cock is connected with a short piece of lead pipe that is used for making connection with the service pipe in the house.

Located at the left of C, in Fig. 58, is the curb-cock, used for shutting off the water from the city lot. The curb-cock, being underground, is reached through an iron tube by means of a wrench attached to a long iron rod. The curb-cock has a protective covering in the form of an iron pipe. The lower end of the pipe screws into the body of the cock. The top end comes just above the grade line of the curb and is covered with an iron screw-cap. The curb-cock is shown in detail in Fig. 64. The pipe B is fastened to the valve at D and A is the screw-cap. In opening and closing the wrench fits over the part C of the valve.

On entering the building the supply pipe should be provided with a stop and waste-cock for shutting off the water from the house and draining the pipes that compose the system of circulation. At V, in Fig. 58, is indicated a stop and waste-cock with[88] the waste pipe B connected with the sewer. This cock is shown in detail in Figs. 65 and 66. The cock is so made that when closed there is a small opening at A, that allows the water from the system to escape through the waste pipe.

From the water supply, the cold-water pipes may be traced in the drawing directly to each of the fixtures of the house. The hot-water pipe leaves the range boiler at the top and connects with each fixture using hot water, thus making the circuit complete. Details of the piping which provides hot water is described under range boiler, page 116.

WATER COCKS

The development of modern plumbing has brought about the use of a great number of household mechanical appliances, that have received trade names little understood by the average person. The lack of distinguishing terms, or language in which to describe plumbing fixtures, often leads to embarrassment, when such articles are to be described to workmen. Common household valves and cocks are so classified by the trade, that mistakes are often made in their designation, because of a limited knowledge of the use of the various articles. A little consideration of the different classes of fixtures will make it possible to state to a tradesman the exact article in question.

The term valve is intended to define an appliance that is used to permit, or prevent, the passage of a liquid through the opening or port which it guards. The term is so general in its application that there are hundreds of different kinds of valves. Even for a single purpose there are many styles of a given kind.

[89]

A cock was originally a rotary valve or spigot used for drawing water. Today there are many kinds of cocks that are not rotary in their movement.

It would be impossible in this work to describe in detail all of the kinds of cocks and valves used in household plumbing. It will, therefore, be the aim to confine attention to one article of a type and to choose such examples as are in general use and that are good representatives of their classes.

Bibb-cocks.

—On the kitchen sink, the water faucets, such as those shown in Fig. 66a, are termed bibb-cocks by the plumber. If the nozzle is plain, it is a plain bibb. If the nozzle is threaded so that a hose connection may be attached as in Fig. 67, it is a hose bibb. Bibb-cocks are found in three general styles: compression bibbs, ground-key bibbs, and Fuller bibbs. The compression bibb takes its name from the method of closing the valve. Fig. 68 gives an example of its mechanical construction. This is a plain solder bibb because the shank A is to be attached by a solder joint. If the part A contained a thread to make a screw joint, such as Fig. 67, it would be a plain, compression, screw bibb. Fig. 68 is another style of compression bibb-cock, largely used on sinks; this cock, being finished with a flange, is a compression flange bibb.

[90]

Fig. 69 shows quite clearly the mechanical arrangement of the compression cock. When the handle is turned the nut C lifts the valve from its seat B, allowing the water to escape. The piece D is generally made of composition rubber that may be bought at the dealers for a trifling amount but it may be replaced temporarily with a piece of leather. The part E is packing, to keep the water from leaking out around the stem. The packing may be obtained from the dealer especially for the purpose or it may be made of a disc of sheet rubber. In fact, anything that can be put into the space will answer the purpose temporarily. The valve is closed by compression, hence the name compression cock. All cocks made to open and close in the same manner are compression cocks.

[91]

Fuller Cocks.

—These cocks take their name from their inventor. They are made to suit every condition for which water cocks are used. Their universal use attests to their utility and excellence in service. Fig. 72 shows the principle on which all Fuller cocks work. The varying conditions under which the cocks are used require a great many forms, but the working principle is the same in all. In these cocks, the valve is a rubber plug or ball that is drawn into the opening by an eccentric piece attached to the handle. The piece D in the drawing is the rubber plug that is drawn against the opening by the crank B, which is worked by the lever handle A. This cock may be repaired, in case it leaks, by unscrewing it at the joint nearest the plug. A wrench and a pair of pliers are all the tools required. The pieces D must be obtained from the dealer. The part J is the packing that keeps the water from leaking out around the stem. The screw-cap H forces a collar I down on the packing to keep it water-tight.

The parts for the Fuller cock that may be obtained for repair are shown in detail on Fig. 73. The ball, which appears in Fig. 73 at D, is the part that receives the greatest amount of wear. If the cock at any time fails to stop the flow of water, a new ball may be put in place by the aid of a wrench and a pair of pliers. The water being first shut off from the system, the cock is unscrewed and the cap E removed with a pair of pliers. The worn ball is then removed and a new one substituted.

Wash-tray Bibbs.

—A special style of cock is made for laundry wash trays in both the Fuller and compression types. Of these the Fuller type is the most convenient as the handle is placed on the side and but one movement is required to open the cock. This style of cock is used on the wash trays shown in Fig. 83.

[92]

Basin Cocks.

—Water cocks for wash basins are made in two general types—the compression and the Fuller types of cocks. Their mechanism is much the same as for other similar styles adapted to the use for basins. The self-closing cocks used so largely on wash basins are compression cocks. Fig. 74 is an example of Fuller basin cock in general use. Compression cocks for the same purpose are shown on the wash basin in Fig. 90.

Pantry Cocks.

—In general form, pantry cocks are the same as those used for basins except that the outlet is elongated.

Valves.

—The distinction between a cock and a valve is not at all definite. Custom has determined that in certain places a cock shall stop the flow of a liquid but in another place, perhaps of a similar nature, a valve shall accomplish the same purpose. The chief distinction between a cock and a valve is that of its external form.

In Figs. 77, 78 and 79 are three examples of valves that are very generally used on pipes carrying any kind of fluid. The valves are shown in cross-section to display the arrangement of the mechanism.

Fig. 77 is an example of the common globe-valve. The name was originally intended to define a valve the body of which was in the form of a globe. The hand-wheel H, attached to the screw-stem S, raises the valve A when desired. The valve makes close contact with the seat C, by means of a composition rubber disc B. The disc B may be renewed when worn out as in the case of the radiator valve already described.

[94]

Fig. 78 represents an angle globe-valve. In general construction it is quite similar to Figs. 14 and 15, but the valve V in this case is a cone-shaped piece of brass, which makes a seat in a depression provided for it. The valve V and the seat are formed as desired and then ground into contact with emery dust or other abrasive material, to assure a perfectly tight joint. When this valve becomes worn and begins to leak, it may be repaired by regrinding, but such work requires the services of a pipe-fitter. The tendency of modern practice is to use valves with the detachable discs, such as that of Fig. 77, because they are easily repaired.

The valve shown in Fig. 79 is known as a gate-valve. The upper part, including the screw and stem, is the same as the globe style but the valve proper is made in the form of two flat gates A-A. When the valve is closed, as it appears in the drawing, the gates are forced against the seats by the cone-shaped piece B, which acts as a wedge, to tightly close the opening. When the hand-wheel is turned to open the valve, the gates are raised and are taken entirely out of the path of the flowing liquid. Gate-valves are used in places where it is desired to obstruct the flow as little as possible. They are somewhat more expensive than globe-valves but are considered worth the extra expense in service.

Kitchen and Laundry Fixtures.

—The development in modern plumbing has wrought many changes in the styles of household fixtures but none has been so great as that in the kitchen sink. The old style, insanitary, wooden sink has been almost entirely replaced by those made of pressed steel or enameled iron. They are made in every desired size and to suit all purposes. They may be plain or galvanized as occasion may require, or the enameled sink is obtainable at a very slight addition in price. The enameled sink has reached a degree of perfection where its durability is unquestioned, and as a consequence kitchen furniture is vastly improved at but little advance in cost.

A modern kitchen in which gas is used as fuel is shown in Fig. 80. Simplicity and neatness of arrangement are the noticeable features. This kitchen is intended to suit the average-sized dwelling and contains all necessary plumbing, cooking and heating apparatus. The hot-water boiler is here shown attached to an instantaneous heater. The common kitchen sink is supplemented[95] with a slop sink and covered with a drain board. This simple kitchen may be elaborated to any extent. Fig. 81 shows a kitchen sink of white enamel with two enameled drain boards. The drain boards are sometimes covered with perforated rubber mats.

[96]

In Fig. 82 is shown an example of the modern basement laundry. The wash-boiler heater is shown on the left. An automatic instantaneous water heater is on the right. The stationary tubs or wash trays occupy the center of the picture. In detail[97] these wash trays appear in Fig. 83. These are enamel-covered ware and are provided with the wash-tray bibb-cocks described above. This type of plumbing represents the most modern of sanitary arrangements.

THE BATHROOM

With the present-day improvements in plumbing, and the perfection in the manufacture of porcelain and enameled iron, the bathrooms of houses of moderate cost have become places of cleanliness, attractive, relatively free from offending odors and supplied with all necessary sanitary fixtures.

Enameled iron has reached a state of perfection where it rivals porcelain in beauty. The forms of the various bathroom pieces have been modeled for convenience in use and grace of form, at the same time the strife of the designer has been to produce articles that not only look well but are convenient and easily kept clean.

Bathrooms need not be expensive in order to be convenient, attractive and useful. The bathroom shown in Fig. 84 is such as is installed in dwellings of moderate price. It possesses every feature necessary to usefulness and comfort. In this room the[98] furnishings are all of enameled iron. The floor is covered with linoleum and the wainscoting with enamel paint.

Bath Tubs.

—Bath tubs are made in sizes that vary in length from 4½ to 6 feet. They are constructed in a variety of forms and of materials to suit all conditions of service. For domestic use they are very generally made of enameled iron. This form of construction produces serviceable and handsome furnishings for the bathrooms of the modest house as well as for the sumptuous bath of the most pretentious residence. An elaboration of Fig. 84 might include the Sitz bath shown in Fig. 85 and the fittings may be chosen from a great variety of forms. The recent styles of enameled tubs are, in design, much handsomer than those with the roll rim and in form such as permits a clean room with the minimum of labor. They are also provided with more convenient water and drainage fixtures.

The tub of Fig. 86 sets flat on the floor and makes a close joint with the wall. It thus prevents the accumulation of dust that is difficult to remove. In addition the fixtures are arranged in a more commodious manner and the general appearance is most pleasing. The arrangement of the fixtures in Fig. 87 gives still greater convenience and being arranged with a shower and protecting curtain, provides all of the conveniences of a luxurious bath without greatly increased cost over the simple tub. The fixtures in this design are all in position of greatest convenience and attached to pipes that are concealed in the wall.

[99]

The fixtures usually provided with the tub are double Fuller or compression cocks for hot and cold water, the overflow and strainer, for the discharge of the water into the sewer in case the tub overflows, and a drain and bath plug.

The double Fuller cock is shown in Fig. 88. It is made to open[100] and close by the same sort of mechanism as is shown in Fig. 71, a description of which appears on page 90.

The overflow is shown in detail in Fig. 89. The part A appears inside the tub. It is made water-tight around the edge C by a rubber washer that is clamped tight to the surfaces by the nut B. In case of leakage, the overflow may be removed for repair by unscrewing the union attached to the piece D and removing the nut B.

The drain-pipe connection is shown in Fig. 89a. The plug D and the flange A show inside the tub. The flange is made water-tight by a rubber washer that the nut B clamps tight to the tub. The part C is a union which permits the tub to be[101] detached from the drain pipe. Repairs to this joint may be made as in the overflow.

They are made in marble, porcelain and enameled iron, the last being the most commonly used. They are made to suit the part of the room to be occupied, whether that is against a wall,[102] a corner, or to stand on a pedestal on the floor. Those intended to fasten to the wall may be supported by brackets or suspended at the back from pieces secured in the wall.

In Figs. 90 and 91 are shown samples of marble-finished wash basins. In former years basins of this type were very much in use, and until the introduction of the modern porcelain and enameled ware, it was the highest type of sanitary plumbing. The water cocks and traps are of the same style and grade as appear on the most modern examples of enameled ware of Figs. 92, 93 and 94. The water cocks used in Fig. 90 are of the compression type. All of the others are of the Fuller type. The basin in Fig. 93 is provided with extra shut-off cocks on the water pipe under the basin. They are added to the plumbing merely as a convenient means of shutting off the water for repair. The wash stand is usually provided with hot and cold water cocks, a waste pipe with its traps and overflow connections.

Traps.

—The waste pipes from the wash basin and bath tub are always provided with some form of trap, to prevent air from entering the room from the sewer, charged with offending odors. Traps are made in many forms, but the purpose of all is to prevent the escape of sewer gas. The plain trap S, shown in Fig. 95, is that used under the basin in Fig. 91. It makes a tight joint by means of the nut B and a rubber washer as in the case of other joints of the kind. The parts C and E are unions that permit the pipe or bowl to be removed without disturbing the remainder of the plumbing. From the form of the trap it will be seen that the U-shaped part below the dotted line F will always remain full of water and so prevents the escape of air from the sewer. In case the trap becomes stopped the obstruction will likely become lodged in this part of the pipe. To clean the trap the screw-plug D is taken out with a pair of pliers and the obstruction removed with a wire.

[103]

The traps used in Figs. 90 and 92 are the same in principle as Fig. 95 but are made to discharge into a pipe placed in the wall instead of under the floor. The trap in Fig. 94 is a form known as the bottle-trap that is sometimes used in the more expensive plumbing.

Another style much used with lavatories is the Bower trap shown in Fig. 96. In this trap the water comes down the pipe B and pushing aside the hollow rubber ball A, enters the space surrounding it and is discharged at C. The ball, being light, is held against the end of the pipe by the water and acts as a stopper to prevent evaporation from taking place. Open traps, such as Fig. 95, if left standing for a long time, may lose sufficient water by evaporation to destroy the water seal and allow the sewer gas to escape. In the use of the Bower trap such occurrence is much less likely to take place.

Fig. 97 is another trap much used on sinks; it is known under the trade name of the Clean Sweep trap. The part C is much larger than the common trap and the water seal is less likely to[104] be broken. The clean-out is larger and the interior is easy of access in case of stoppage.

The simplest and most commonly used trap in cheap plumbing is that of Fig. 98. It is a lead pipe bent in the form of an S. It is the same in shape as Fig. 95 and performs its work as well but does not have the means of detachment shown in the latter. Traps of many other forms are in use but all have the same function to perform and the mechanical make-up is much the same as those described.

The plan of attachment of the various bathroom fixtures of the soil pipe must always depend on local conditions. The object is to conduct the waste water to the sewer in such a way as to give the least opportunity for stoppage and to prevent sewer gas from escaping into the house. To accomplish this purpose the pipes and traps are arranged according to a plan proposed by the architect, plumber or other person familiar with the principles of plumbing. Since these pipes are placed in the walls and under the floors, where they are not readily accessible, it is necessary that their arrangement be made with care and that the workmanship be such as to assure correct installation.

In Fig. 99 is shown a common method of connecting bathroom[105] fixtures with the sewer. The drawing shows a bathroom with the floor broken away to show the pipe connections with the bath tub, wash basin and closet. The overflow pipes O and V and the drain pipes D and R from the wash basin and bath tub empty into a large lead drum-trap T, set under the floor. This trap takes its name from its shape. It is set in position as dictated by the conditions under which it is used. The nickeled plate P, screwed into the top of the trap, comes just above the bathroom floor. This plate is easily removed in case of stoppage. It is made air-tight by a rubber ring placed under the cover and which makes a joint with the top edge of the drum.

It will be noticed that the waste pipes from the bath tub and wash basin enter the trap near the bottom and discharge at the opposite side near the top. The water will stand in the trap and pipes level with the bottom of the discharge pipe and thus form a seal that prevents the escape of sewer gas. This is a common form of non-siphoning trap. It is non-siphoning because it cannot lose its seal by reason of the siphoning effect of the water as it passes through the waste pipes on its way to the sewer. Another form of non-siphoning trap is the clean sweep trap shown in Fig. 97. Such traps as Figs. 95 and 98 are siphoning traps, since it is possible, in this form of trap, for the water to be so completely siphoned that not enough remains to form a seal. The small drawing, marked Detail L, is another method of connecting the same arrangement of fixtures. The waste pipe enters the trap as before but discharges immediately opposite. The level of the water stands in the pipes as indicated by the dotted line.

Back-venting.

—To prevent the possibility of loss of seal by siphoning and the escape of sewer gas, traps are back-vented to the main stack or to a separate vent stack. The venting is accomplished by joining a pipe to the top of the trap or to some point in its immediate neighborhood, and connecting this with the main stack or the vent stack. The water in a trap so vented will be open to the air from both sides and consequently can never be subject to siphonic action.

In the average-sized dwelling where non-siphoning traps are used, back-venting is not necessary, but in large houses and[106] in plumbing where siphon traps are used, vent pipes must be attached to the traps to assure a satisfactory system.

Fig. 100 furnishes an example of back-venting, applied to the bathroom shown in Fig. 99. In the former figure the bath tub and wash basin are connected with the waste pipe by siphon traps. A siphon trap may lose its seal in two ways: by self-siphonage, or by aspiration caused by the discharge of the water from other fixtures. In the discharge of the siphon trap, such as B, in Fig. 100, the long leg of the siphon, formed by the discharge pipe, may carry away the water so completely that not enough remains in the trap to form a seal. Again, the discharge of the water from the bath tub through the waste pipe tends to form a vacuum above it and in some cases the seal in B is destroyed by the water being drawn into the vertical pipe. The possibility of either of these occurrences is prevented by back-venting.

In Fig. 100, a pipe from the main stack is connected with the bend of the trap at B and also to the waste pipe outside the trap at T. A vent is also taken from the drain C, at a point just below the trap in the closet seat. The object of all of the vents is to prevent the tendency of the formation of a vacuum from any[107] cause that will carry away the water seal of the trap and allow sewer gas to enter the house.

The closet seat also contains a trap which will be described later. It connects with soil pipe S, leading to the sewer by a large lead pipe C.

All of the pipes under the floor, leading to the soil pipe, should be of lead. The pipes above the floor are generally of iron or nickel-plated brass. All of the connections in the lead pipes are made with wiped joints; that is, the connections are made by wiping hot solder about the joint, in a manner peculiar to this kind of work, in such a way as to solder the pipes together. The joints made in this manner are perfectly and permanently tight. Lead pipes are used under such conditions, because lead is the least affected by corrosion of any of the metals that could be used for such work.

Soil Pipe.

—The soil pipe, of which the waste stack or house drain is composed, is made of cast iron and comes from the factory covered with asphaltum paint. It may be obtained in two grades, the standard and extra heavy. The only difference is in the thickness of the pipe. The former is commonly used in the average dwelling. One end passes through the roof and the other end joins to the vitrified sewer tile under the basement floor. The joints must be perfectly tight, because a leak in this pipe would allow sewer gas to escape into the house. One end of each section is enlarged sufficiently to receive the small end of the next section. The joints are made with soft lead. The pipes are set in place and a roll of oakum is packed into the bottom of the joint, after which molten lead is poured into the joint, filling it completely. The oakum is used only to keep the lead in the joint until it cools. After the lead has cooled it is packed solidly into the joint with a hammer and calking tool. The calking is necessary because the lead shrinks on cooling and makes a joint that is not tight. Well-calked joints of this kind are air-tight and permanent. Detail N (Fig. 99) shows the arrangement of the parts of the joint as indicated at A. The blackened portion represents the lead as it appears in the joint.

Detail M (Fig. 99) shows the methods of attaching the closet seat to the lead waste pipe C. The end of the lead pipe is flanged at the level of the floor, as shown at C in the detail drawing.[108] The depression D, around the connection, is then filled with glazier’s putty and the seat is forced down tightly in place and fastened with lag screws.

The pipe C, from the closet, and that from the trap T, being of lead, a special joint is necessary in connecting them with the soil pipe, because a wiped joint cannot be made with cast iron. To make such a connection the end of the lead pipe is “wiped” onto a brass thimble, heavy enough to allow it to be joined to the soil pipe by a calked lead joint. The brass thimble is then joined to the cast-iron pipe by a calked lead joint.

Water Closets.

—Water closets are made in a great number of styles to suit the architectural surroundings and the various conditions under which they are to be used. Many forms of water closets are manufactured to conform to special conditions, but those commonly used in the bathrooms of dwellings are of three general types. The mechanical construction of each is shown in the following drawings, Figs. 101, 102 and 103 showing respectively in cross-section the principle of operation of the washout closet, the washdown closet and the siphon-jet closet.

Washout Closets.—This type of closet has in the past been used to a very great extent. It does not perform the work it has to do, so perfectly as the others, because the shallowness of the water in the bowl allows it to give off odors, and because it is difficult to keep clean. The action of the closet is as follows: When the closet is flushed the water enters the rim at A, and the greater portion of it is washed downward at B to dislodge the contents of the bowl. A lighter flush is sent through the openings[109] in the side, which serves to wash the entire surface. The direction of discharge is forward, where it dashes against the front of the bowl and then falls into the trap. The only force received to carry the water to the trap is from falling through the distance from the point where it strikes the front. The flushing action is obtained from the use of a large volume of water. As the discharged matter is dashed against the front of the bowl, the flushing action of the water is not sufficient to remove all the stains; the result is an accumulation of filth. This part of the bowl is out of sight; hence, it is seldom kept clean. The name washout comes from the action of the water to wash out the contents of the bowl.

Washdown Closets.

—As shown in Fig. 102, the action of this closet is to wash the contents of the bowl directly down the soil pipe. The depth of the water at A is much greater than at the corresponding point in the washout closets; as a consequence fecal matter is almost submerged. The main objection to this closet is that it is noisy. Fig. 104 shows another form of washdown closets. This closet is open to objection because of faulty design; the part A is difficult to keep clean because of its shape.

As illustrations of high flush tanks, those shown in Figs. 105 and 106 furnish examples of a simple and efficient form. The details of the mechanism of this type of tank are shown in Fig. 107. The pipe from the water supply is attached at G to the automatic valve F, which keeps the tank filled with water. The piece F of the valve is held against the opening by the pressure exerted through the float E. The float is a hollow copper ball.[111] As the ball is lifted it exerts a pressure in proportion to the amount it is submerged. When the water reaches the level A-A, the valve is tightly closed. As the water is discharged from the tank the ball follows the level of the water and opens the valve, allowing the water to enter and again fill the tank.

The siphon is made of cast iron, and in the figure is shown cut through the center. The lower end fits loosely in the piece K, and makes a water-tight joint around its outer edge, by resting on a rubber ring C-C. The right-hand side of the siphon is open at H, and when the tank is full, the level of the water is at A-A, which is almost at the top of the division plate. To discharge the tank, the chain L, attached to the lever B, is pulled down; this action raises the siphon from its seat. As soon as the siphon is lifted, the water rushes through the opening around C-C, into the pipe K; this causes a partial vacuum to form in D, and the water is lifted over the division plate K, and flows out at D, forming the siphon. As soon as the siphonic action begins the siphon may be dropped back on the seat and the water will continue to discharge until the tank is empty.

Low-down Flush Tank.

—The low-down flush tank for water closets has met with so much favor that it has to a great extent displaced the high tank. The reason for this is because of its advantages over the other style. The low tank is more accessible, more easily kept clean, and better adapted to low ceilings. It is used successfully as a siphon tank, but other forms are in use with satisfactory results.

Fig. 108 gives a perspective view of one style of this type of tank attached to a siphon-jet closet. Figs. 109 and 110 give the[112] details of the construction of two forms of this type of tank, both of which have given efficient service. The drawing shows the tanks with the front broken away to give a view of the working parts. The water enters the tank and is discharged at the points indicated. The float and supply valve works exactly as described in the high tank. The drawing in Fig. 109 shows the tank in the act of discharging. The discharge valve is raised as shown at E. When the water is completely discharged, the float occupies the position shown dotted. When the float reaches this dotted position, its weight pulls down the piece A. This releases the lever B, and the attached stopper E, which falls and closes the discharge orifice. While the tank is filling with water, a stream flows through the small pipe D, to replenish the water in the closet that has been discharged in siphoning. When the tank is full of water, the pieces A and B occupy the positions shown dotted. To discharge the tank the trip is pushed down. This action raises the lever to the position B, and with it the attached stopper E. The piece C falls and the opposite end A holds B suspended until the tank is completely discharged.

The action of the tank shown in Fig. 110 is the same as the others except that of the discharge mechanism. In the drawing, the tank is full of water ready to be discharged when required.[113] A hollow rubber ball E serves as a stopper for the discharge pipe. The ball is kept in place, when the tank is filling, by the pressure of the water above it. The discharge is started by pressing down the trip on the front of the tank. This raises the ball from its seat, and being lighter than water, it floats, thus leaving the discharge pipe open until the tank is empty, when the ball is again back on its seat. As the tank fills the pressure of the water above prevents the ball from again floating, until lifted from its seat. The supply valve and refilling pipe D is the same in action as in the other tank.

Closet seats furnish an inviting receptacle for waste material of almost every kind. Stoppages are not uncommon and are generally found in the trap. One method of removing obstruction is by use of the plumbers’ friend. This device is shown at[114] P-R, in Fig. 111. It consists of a wooden handle P attached to a cup-shaped rubber piece R.

The plumbers’ friend is shown in the figure, placed to remove an obstruction S that is lodged in the trap. A sudden downward thrust causes the rubber cap R to entirely fill the closet outlet and the resulting pressure to the water is generally sufficient to force the obstruction through the trap to the soil pipe.

The kitchen sink is another place that affords opportunity for accumulation that stops the waste pipe. Accumulation of grease in the trap is a common cause of trouble. This may be remedied to some extent by the use of potash or caustic soda. When the pipe is stopped and the trouble cannot be reached from the trap, a common method of removing the stoppage is that suggested in Fig. 112. A piece of heavy rubber tubing is forced over the water tap and the other end tightly wedged into the drain pipe; the water is then turned on and generally the pressure is sufficient to force the accumulation down the pipe.

Sewer Gas.

—The prevalent fear of the deleterious effect of escaping sewer gas is one that has been magnified to an unwarrantable degree. Among bacteriologists it is very generally recognized that none of the dreaded diseases to which the human kind is susceptible are transmitted by gases. The one possible harmful effect recognized in sewer gas by scientists is that produced by carbon monoxide. Sewer gas often contains, from escaping illuminating gas, sufficient carbon monoxide to produce the poisoning effect characteristic of that gas but the possibility of danger is quite remote. The leakage of sewer gas is detected by the sense of smell sooner than in almost any other way. While leaks in sewer pipes are unhygienic in that they are conducive to undesirable atmospheric conditions, they should not be looked upon as the agents through which transmissible diseases are carried.

[115]

To the average person the term sewer gas conveys the impression of a particularly loathsome form of vaporous contagion, capable of distributing every form of communicable disease. To the scientific mind it means no more than a bad odor. Sewer gas is really nothing but ill-smelling air.

RANGE BOILERS

The hot-water supply to the household is of so much importance, that the installation of the range boiler should be made with great care, and an understanding of the principle on which it works should be fully appreciated by all who have to do with its management. The ability of the boiler to supply the demands put upon it depends in a great measure on its size and the arrangement of its parts, but proper management is necessary to assure a supply of hot water when required.

Range boilers are used for storing hot water heated by the water-back of the kitchen range or other water heater, during a period when water is not drawn. It serves as a reserve supply where the heater is not of sufficient size to heat water as fast as is demanded.

As commonly used, range boilers are galvanized-steel tanks made expressly for household use. They are standard in form and may be bought of any dealer in plumbing or household supplies. In capacity they range from 20 to 200 gallons and are made for either high-or low-pressure service. They are said to be tested at the factory to a pressure of 200 pounds to the square inch and are rated to stand a working pressure of 150 pounds. Range boilers are galvanized after they are made and coated both inside and out. The coating of zinc received in the galvanizing process helps to make their seams tight and at the same time renders the surface free from rust.

There is no definite means of determining the size of tank to be used in any given case, because of the varying demands of a household but a common practice is to allow 5 gallons in capacity to each person the house is able to accommodate.

The Water-back.

—The most common method of heating water for the range boiler is by use of the water-back or water-front of the kitchen range. The water-back is a hollow cast-iron piece[116] that is made to take the place of the back fire-box lining of the range. In some ranges the heater occupies the front of the fire-box instead of the back, in which case the heater becomes the water-front.

The arrangement of pipes connecting the source of water supply with the boiler is such that cold water is constantly supplied to the tank as the hot water is drawn. If no water is drawn from the tank, it will continue to circulate through the tank and heater, the water becoming constantly hotter.

The connecting pipes are usually of iron but sometimes pipes of copper or brass are used. The joints should be reamed to remove the burr that is formed in cutting. The angles should be 45-degree bends or better still 90-degree bends in connecting the heater with the tank so as to cut down the amount of friction as much as possible.

In Fig. 113 is shown a standard range boiler connected to the range. The water is brought into the top of the tank through the pipe a-a, and passing through it enters the water-back by means of the pipe b. After passing through the water-back the water again enters the tank through the pipes c and d, as indicated by the arrow. The flow pipe (carrying the out-going water) from the water-back may be connected with the tank at e, as shown dotted or in some cases the connections are made at both places. The velocity of circulation depends on the vertical height of the column of hot water and the greater height will, therefore, improve the circulation and thus increase the efficiency of the heater. The circulation of the water through the tank and heater is produced by its change in weight as the water is heated. As the hot water comes from the water-back it rises in the pipe because it is lighter in weight than the cooler water of the tank. In[117] the case of the pipe shown dotted in Fig. 113 the longer vertical rise will give a greater upward velocity of the hot water and consequently a better circulation through the entire circuit.

The construction of the water-back is shown in the small drawing. The connections are made at b and c as before. A division plate in the water-back causes the water flowing in at b to follow the length of the heater at the bottom and return at the top as indicated by the arrow, when it is discharged at C.

The hottest water is always at the top of the tank and the temperature grades uniformly from the hottest at the top to the coolest at the bottom. The reason for extending the pipe a so far down into the tank is that the cold water may not mingle with the hot water and reduce its temperature on entering the tank. Near the top of the pipe a is a small hole f that is intended to prevent the water from being siphoned from the tank in case a vacuum is formed in the cold-water pipe. In this arrangement the water enters and leaves at the top of the tank. In case the supply is shut off at any time the tank is left almost full of water, because the siphoning effect cannot extend below the small hole f.

Excessive Pressure.

—Accidents due to the explosion of hot-water backs are not at all rare and it should be borne in mind that there is danger of excessive pressure being formed should the pipes b and c become stopped. Under normal conditions the pressure generated by the heated water is relieved by the water in the tank being forced back into the supply pipe. The pressure in the tank, therefore, cannot become greater than that of the source of supply, but if b and c should become stopped with the water-back full of water a dangerous pressure might result. The greatest danger from this cause is that of freezing. It frequently happens that houses are closed during cold weather and the water-back is left undrained. The water freezes and when a fire is started in the range, the ice in the water-back is the first to melt. In a short time steam will be generated that will soon produce a sufficient pressure to burst the water-back. This has happened many times with disastrous results. Such dangers may be avoided by the exercise of a reasonable amount of care in the management of the range. To drain the water-back, the water is first shut off at the point where the supply[118] pipe enters the house. The water in the range boiler is then drawn off by means of the cock h.

Blow-off Cock.

—When a considerable amount of sediment is carried in the water the range boiler acts as a settling tank and the deposit accumulated at the bottom will in time amount to a source of trouble. The accumulation is shown in Fig. 114. The part W, which connects with B, is sometimes provided with a blow-off cock that will admit of a discharge of the sediment. More commonly the piping is arranged as shown in Fig. 113, when sediment is removed by occasionally drawing water from the cock h.

Location of Range Boiler.

—It is sometimes desired to place the range boiler on a different floor, either above or below the range. While such arrangements are entirely possible the circulation of the water is not so good as that described above. The weight of the two columns of water in the connecting pipes are so nearly balanced that good circulation is not always possible. In Fig. 115 the connections are shown, where the tank is located in the basement. In connecting the water-back to the tank under such conditions the piping is relatively the same as is shown in the dotted connections of Fig. 113, but the connections are longer. The circulating pipe comes from the bottom of the tank and leads to the bottom of the water-back. The flow pipe from the top of the water-back is extended up to a distance equal or greater than the distance from the water-back to the[119] bottom of the tank. The hot water is taken from the top of the flow pipe at any place above the tank.

Horizontal Range Boilers.

—It occasionally happens that in a small kitchen there is no convenient floor space for the range boiler and it becomes necessary to suspend it from the ceiling. It is perfectly possible to station the ordinary range boiler in such a position and have it work fairly well but from the location of the cold-water inlet, only that part of the range boiler above the cold water pipe is actually used for storage. The water in the lower half constantly mixes with the entering cold water before it is heated by passing through the water-back. When hot water is drawn from the top of the range boiler, cold water enters by the cold-water pipe and reduces the temperature of most of the lower half. Fig. 117 illustrates such an arrangement. In this case the pipes connected with the water-back are those that correspond to the circulating pipes a and e in Fig. 113.

[120]

Suppose the range boiler is full of water, and that it is being heated. The lower pipe at the left-hand end is conducting the water to the water-back and it is being returned to the range boiler by the upper pipe at the same end. When the hot water is drawn from the top of the range boiler by the hot-water pipe, the entering cold water mixes with hot water in most of the lower half of the range boiler before it has been heated by passing through the water-back and so reduces the temperature of most of the lower half of the tank.

A much better tank for the purpose is that indicated in Fig. 118. This is a tank made particularly for such a location. The cold water enters at the bottom of the tank and also leaves the bottom on its way to the water-back. Circulation takes place through the water-back as before but when hot water is drawn from the top of the tank, the entering cold water at the bottom mixes with only that at the lower part of the tank and so cools but a small amount of the hot water in storage. Hot-water tanks of this kind are tapped for pipe connections in two places on both the top and bottom sides and also at the ends as shown in the drawing.

[121]

Tank Heaters.

—When the demand for hot water is sufficient to warrant a separate hot-water heater the apparatus similar to Fig. 119 is used. With such a heater, the conditions of overheated water—to be described later—may be almost entirely avoided. In this case the connections are arranged similarly to those of the range boiler but a separate furnace takes the place of the water-back. The heater is simply a small furnace made expressly for heating water. Connected with the discharge pipe p is a draft-regulating valve which controls the drafts of the heater. The draft-regulator is set to so control the furnace that water at the desired temperature will always be in the tank. The mechanism of this regulator is the same as the draft-regulator described under hot-water heating plants.

When the water at a high temperature is drawn from the tap a considerable part of it will instantly vaporize, because of the reduced pressure. If water at a pressure of 25 pounds is drawn from the faucet, the temperature, 258°F., is sufficient to send all of the water instantly into steam. This high temperature will scald at the slightest touch. The water drawn from the faucet[122] will continue to vaporize as it comes into the air until the water in the tank is cooled by the incoming cold water. The only means of relieving the overheated condition is to open the faucet a slight amount and allow a portion of the heated water to be drawn off.

It is evident from what has been said of the range boiler that it operates under a variety of conditions. It is first a storage tank in which is accumulated the water, heated from a greater or less period of use of the range. Should the range fire be maintained through the day or night the supply of hot water will be excessive and superheating is the result. If the heater is to be used during short periods of time, the piping should be arranged to produce the best circulation; on the contrary, should the heater be used continuously—as in the case of a furnace coil—a slow circulation through the tank is most to be desired and the piping should be arranged for that purpose.

In the use of furnace heaters, superheating is likely to occur during cold weather when a hot fire must be used over a long period of time. In order to conserve the heat accumulated under such conditions a hot-water radiator is frequently connected with the range boiler through which to dispose of the excess heat. This radiator may be placed in any desired position and so connected by a valve as to discontinue its use at any time.

Furnace Hot-water Heaters.

—It is sometimes more convenient to use the furnace as a means of heating water than the kitchen range. Such an arrangement is shown in Fig. 120, where a loop of pipe in the fire-box of the furnace takes the place[123] of the water-back. The arrangement of the pipes in the range boiler are as before, the water entering the tank through the pipe A, circulates through the pipes B and C, receiving its heat while passing through the loop in the furnace, in exactly the same way as in the water-back. It would be quite possible to also connect the kitchen range with the tank as shown by the dotted lines indicating the water-back. Such an arrangement would virtually be that shown in Fig. 116, where the two heaters on different floors are connected with the boiler.

Fig. 122 shows the heater connected with a range boiler. In this case the heater may be considered as taking the place of the water-back. It may, however, be used as an auxiliary heater. In the picture of the kitchen shown in Fig. 80, an instantaneous heater is shown attached to the range boiler. It is located in this case between the kitchen range and the boiler.

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CHAPTER VII
WATER SUPPLY

The use of water enters into each detail of the affairs of everyday life and forms a part of every article of food; its quality has much to do with the health of the family, and its convenience of distribution lends greatly to the contentment of its members. The family water supply should be as carefully guarded as means will permit, and judicious care should be exercised to prevent the possibility of its pollution. Where the source of the water is known, it should be the subject of unremitting attention.

Water comes originally from rain or snow and as it falls, it is pure. Water, however, in falling through the air absorbs the contained vapors and washes the air free from suspended organic matter in the form of dust, so that when it reaches the earth rain water contains some impurities.

As the water is absorbed by the earth, it comes into contact with the mineral matter and organic materials of animal and vegetable origin contained in the soil; and as water is a most wonderful solvent, it soon contains mineral salts and possibly the leachings from the organic substances through which it passes. The impurities usually found in well water are in the form of mineral salts that have been taken up from the earth, but other contaminating materials may come from the surface and be carried into the well by accidental drainage.

Water that is colorless and odorless is usually considered good for drinking and in the absence of more accurate means of determination may be used as a test of excellence; but it often happens that water possessing these qualities is so heavily freighted with mineral salts as to be the direct cause of impaired health. Again, water that appears pure may be polluted with disease-producing bacteria to such an extent as to endanger the lives of all who use it. The fact that a source of drinking[126] water bears a local reputation for purity, because of long usage, cannot be taken as a test of its actual purity until it has been subjected to chemical and bacterial examination.

It must not be inferred that all water is likely to be unsuitable for drinking; there is, however, a possibility of the water being polluted from natural sources and from accidental causes, that are sometimes preventable; and the only means of determining the purity of water is by chemical and bacterial examining.

Water Analysis.

—In order to be assured as to the quality of drinking water, it should be subjected to analysis and the result of the analysis inspected by a physician of good standing. Such analysis may usually be obtained free of charge from the State Board of Health and if asked, the Chief Chemist will usually give his opinion regarding the quality as drinking water.

In chemical water analysis, the total amount of solids, regardless of their nature is taken as indicative of its excellence for drinking purposes. These solids may be either in suspension and give the water a color or produce a turbidity, or they may be entirely in solution and the water appear colorless. English authorities on the subject place the allowable proportion of solids at 500 parts to the million. Any water that contains more than 500 parts to the million is condemned for drinking purposes. Water containing 500 parts or less to the million is considered good. The Standard of the American Board of Health permits the use of water for city supply that contains 1000 parts of solid matter to the million.

The amount of solids contained in water is not at all a definite indication of its quality for drinking purposes, as may be inferred from the widely varying amounts permitted by the different authorities, but it gives an indication of its character because of the known physiological action of the contained solids.

Chemical analysis alone cannot be taken as a complete indication of the character of water, because such analysis shows nothing of the bacteria that may be present. The organic matter may indicate the possible presence of bacteria, but microscopic examination will be required to determine its harmful properties.

As examples of the chemical constituents of potable waters, the following furnish illustrations of different types of water in general use.

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Pokegama Water.

—The water from Pokegama Spring at Detroit, Minn. is used widely through the Northwest as a table water. It is considered to be a very excellent drinking water because of the low amount of solids and the absence of any deleterious constituents. The complete chemical analysis as reported by the North Dakota Pure Food Laboratory is as follows:

The total solids, 20.2611 grains per gallon, equivalent to 346.85 parts per million, is very low and composed of carbonates of sodium, calcium and magnesium, none of which are in any way harmful even in much larger quantities. The amount of organic matter is practically nothing.

River Water.

—The water supply of the city of Fargo, N. D., is taken from the Red River of the North, which after being filtered through a mechanical filtration plant is supplied to the water system of the city. The river water in its raw state is considered unfit for drinking because of the amount of organic matter present at different times of the year.

Analysis of raw water from intake pipe, April 14, 1913:

In this water neither the solids nor the organic matter are at all high but during a part of each year there are many pathogenic[128] germs present, the contained typhoid bacillus being the most feared. The following is an analysis after the water has been filtered, April 14, 1913:

It will be noticed that in the process of filtration there has been removed from the water 35 parts to the million of organic matter and with probably 99 per cent. of the pathogenic bacteria. In addition there has been removed 40 parts to the million of mineral solids, the removal of which has changed a very hard water to that which is reasonably soft. The process of filtration has changed water that is generally condemned for drinking to one that is considered remarkably good.

Artesian Water.

—The analysis of the sample of artesian water given below is an example of the water analysis made by the North Dakota Pure Food Laboratory. It furnishes an illustration of the type of reports that are returned from samples of water submitted for examination. This report was in the form of a letter which was taken at random from the files of the laboratory.

Sample of artesian water No. 1936 from Moorhead, Minn.:

“The solids in this water are made up of sodium chloride, salt, 116 parts; volatile and organic matter, 90 parts; lime sulphate, a trace; lime carbonate, a slight amount; magnesium carbonate, a slight amount; and the balance of the solids are all wholly made up of sodium bicarbonate. This water is low in solids and of good quality.”

Medical Water.

—The solids that occur most commonly in spring and well water appear in the form of mineral salts. It[129] frequently happens that salts giving a cathartic action are present in sufficient quantity to render the water objectionable when used for drinking. Sodium chloride or common salt frequently occurs in quantity sufficient to be distinctly noticeable. Magnesium sulphate (Epsom salts) and sodium sulphate (Glauber salts), both of which are well-known laxative salts, very commonly occur in well water. The carbonates of calcium and sulphur also frequently found in well water are inert in physical action when taken in drinking water. The presence of laxative salts in spring water has given great celebrity to many springs both in Europe and America that are famous as cures for all manner of human ills. Such curative value as these springs possess is derived from the cathartic salts contained by the water.

The table of contents of the Saratoga Congress Water as given by Dr. Woods Hutchinson shows the solids of one of the most celebrated of America’s medicinal waters.

When reduced to ordinary measure and given their common names the mineral solids in a gallon of this water will be approximately:

The total solids, 570 grains per gallon, contained in Saratoga water, gives the remarkably high content in total solids, of 9758 parts per million; this is almost ten times the limit of the American standard. While such water would not do for constant consumption, it is taken for considerable periods of time with beneficial results and is recommended by many authorities as a water of great medicinal potency.

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While most medical authorities condemn the use of water high in solids, the ideal drinking water is neither soft water nor distilled water—that is, water that is perfectly free from any saltiness—but one that contains a moderate amount of the ordinary constituents of the earth. It is reasonably safe to assume that any unpolluted water containing as high percentage of solids as 1000 parts of total solids to the million, and that is agreeable to the taste, would be safe for drinking.

“Chemical analysis in general indicates the possible pollution of water. A relatively high content of organic substances, nitrate, chlorides and sulphates, might indicate contamination, particularly when ammonia is also present. On the other hand, a high content of just one of the above-mentioned substances, be it organic, chloride, nitrate or sulphate, may originate from the natural soil strata.”

Organic Matter.

—Organic matter may come from peat swamps, decaying leaves and grasses; or it may come from decayed animal matter which finds its way into the soil; or worst of all it may come from cesspools or other sewage. While the presence of organic matter does not necessarily indicate the presence of disease-producing bacteria, it is a medium in which such germs live and multiply; for that reason it is an indicator of possible harm.

Ammonia.

—In the analysis of water the presence of ammonia is an indicator of organic matter. Ammonia is not of itself injurious but it indicates the presence of matter in which bacteria[131] find conditions suited to their growth. Free ammonia is usually considered an indicator of recent pollution, while albuminoid ammonia indicates the presence of nitrogenous matter that has not undergone sufficient decomposition to form ammonia compounds.

Hardness in water may occur in two forms—as temporary hardness or as permanent hardness. When bicarbonate predominates as the hardening agent, the water is said to be temporarily hard because, when heated to boiling, the bicarbonate is precipitated and the water is thus softened. When softening of such water is to be done on a large scale, chemical treatment is more satisfactory. Water containing bicarbonate of lime may be softened by adding a pound of lime to 1000 gallons or 1 pound of lime to 165 cubic feet of the water. This quantity of lime is sufficient to remove 10 grains of the bicarbonate to the gallon.

When the mineral matter is in the form of sulphates, mainly sulphate of lime or magnesia, the water is said to be permanently hard, because boiling will not soften it. Such water may be softened by adding soda ash or impure carbonate of soda. One pound to 1¼ pounds of “washing soda” to each 1000 gallons of water will render such water soft; by its action the sulphate of lime is precipitated and settles to the bottom of the container; the water may then be siphoned off leaving the precipitate in the bottom.

Iron in Water.

—Water containing iron is found in many wells and springs. While iron is not harmful, it is objectionable to[132] taste and stains most things with which it is long in contact. It may be precipitated with lime and removed as the sulphate of magnesia described in the preceding paragraph.

Chlorine.

—The presence of chlorine in water may indicate the presence of polluting matter in the form of sewage but only when the amount is considerably above the normal amount of chlorine that is contained in the soil in the community from which the water is taken. An increase of the chlorine in the water would indicate a probable pollution from sewage.

Pollution of Wells.

—The water from wells is often polluted by seepage through the earth from sources that might be prevented. Fig. 123 illustrates some of the commonest sources of contamination that through carelessness or ignorance are located in the neighborhood of the family water supply. The drainage from such sources of pollution is often directed toward the well and many cases of ill-health, disease or death are the direct consequences of drinking its water. It may be readily observed, in the case of the well illustrated, that the more water that is pumped from the well, the greater will be the tendency of the water from each of the sources of pollution to reach the well.

Another common cause of contamination of well water is that of imperfect well curbs that allow the waste water or surface water to flow into the well. The area about the well should be graded to allow no standing water, and the waste should be conducted away without permitting it to collect in standing pools.

Drainage from manured fields or other places where disintegrating animal or vegetable matter may be absorbed by water is[135] often the cause of temporary pollution, where the water is carried to low-lying wells. Wells located in low areas that receive the drainage from such places may be suspected of pollution during the spring or early summer, when during the remainder of the year the water is pure.

In connection with any water suspected of pollution, it is well to remember that by boiling the water used for drinking, its harmful properties are entirely destroyed.

Safe Distance in the Location of Wells.

—In the location of a well, the distance of safety from sources of pollution will depend, in a considerable measure, on the character of the soil and the quantity and concentration of the pollution material entering the ground water. When coming from the surface, the danger is usually neither great nor difficult to avoid; but when cesspools and privies in the neighborhood are sunk to a considerable depth in porous earth, from which the supply of water is drawn, the polluting material may reach the well undiluted. No absolute radius of safety can be given, but certain generalizations as to conditions may be made as to character of soil and the different topographical conditions which surround a safe location.

In ordinary clay, or in clay mixed with pebbles and in soils of the same general nature, through which the water circulates by seepage, the pollution is not likely to be carried to a distance of 100 feet. Clay offers marked resistance to the passage of water, which in beds of 3 to 5 feet thick will act as protection from pollution from above. In sandy soils the movement of water is faster than in clayey soils, but 150 feet may be taken as a safe distance, unless the downward slope of the land carries the polluting material directly to the well.

Surface Pollution of Wells.

—In dug wells, pollution from the surface is due most commonly to careless construction and lack of care. In Fig. 124 is indicated the most common cause of surface pollution. The figure represents a well that has been curbed with planks. Through lack of care the earth has sunken at the top, permitting the surface water to flow into the well. The top of the well is on a level with the surface and covered with loosely laid boards which allow the waste water to drip through the joints. Such a well, even though the source of supply is good, will likely yield water of inferior quality.

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In bored wells, polluting water may enter through the uncemented joints of the tiling or through the joints in the staves of wooden tubing; in drilled or driven wells, through leaky joints or holes eaten in the iron casing by corrosive waters. By cementing the interior surface of stone-or brick-curbed wells, by replacing wood with cement or other impervious curbs and by substituting new pipes for leaky iron casings, the entrance of polluting water may be prevented.

In the average home the water supply is most commonly taken from a well, the water from which comes through the earth from unknown sources, and the character of chemical salts or organic matter the water contains will depend on the kind of soil through which it passes before reaching the well.

The water from wells, whether deep or shallow, is generally of relatively local origin, it being absorbed by the soil and carried to the water stratum by percolation. If the soil contains soluble mineral salts the water will contain these materials in quantities depending on the amount of the salts present in the earth. If the earth contains organic matter as pathogenic bacteria the water is likely to contain these bacteria in like numbers as they are present in the soil through which the water filters.

As usually encountered, the water-bearing earth occurs in sheets rather than in veins or streams. The movement of the water in such areas follows the contour of the earth and is influenced by the varying amount of rain or snowfall and the atmospheric pressure. The lateral movement is often only a few inches a day and in some places no lateral movement occurs at all. Underground streams of any kind are not usually found except in limestone regions.

As a rule, a well is formed by digging or boring into the earth[137] until a stratum of water-bearing soil is encountered, the type of the well being determined by the character of the earth and the location of the water-bearing soil. The water from the surrounding area fills the opening to the height of the saturated soil. As the water is pumped from the well it is replenished by the flow from the surrounding earth. If the soil is porous, as in the case of gravel, the water will refill the well almost as fast as it is taken away by the pump. If the soil is dense and the inward flow is slow, the well when once exhausted may be a long time in refilling.

Water Table.

—The upper level of the saturated portion of the soil is known as the water table. It has a definite surface that conforms to the broader surface irregularities. While a definite, determinable water table appears only in porous soil, it exists even in dense rocks. It rises and falls in wet seasons and in drought. In exceptionally wet seasons the water table may be at or above the surface. Under such conditions the opportunities for the pollution of wells is much increased. In particularly dry seasons the water table may sink below the bottom of the well, when it is said to “go dry.” The water table follows the surface contour in a manner depending on the character of the soil. It is flattest in sand or gravel areas but in clay it follows the contour of deep slopes with but slight variation.

In most cases the operators are entirely honest in their belief and in a large proportion of trial their efforts have been successful in locating desirable wells; but it has many times been proven that the movement of the rod is due to an unconscious muscular movement of the arms and hands, in places where the operator has previously suspected the presence of water. The operator of the devining rods is most successful in regions where water occurs in sheets, such as often occur in gravel or pebbly clay. The successful use of the devining rod cannot be explained by any scientific reasons. There have been invented a number of devining rods, claimed by their inventors to be based on[138] scientific laws; but the government has not yet granted patents to appliances of the kind.

Selection of a Type of Well.

—The chief factor which controls the selection of a type of well is the nature of the water-bearing earth, the amount of water required, the cost of construction and the care of the resulting supply.

If a large amount of water is to be demanded of a well, to be dug in soil through which the water percolates slowly, the well must be large in diameter, in order that the necessary supply may be accumulated. If the earth is porous and yields its water readily, a small iron pipe driven into the ground may supply the desired amount.

The character of the water-bearing material is of the greatest importance in determining the yield of the well. In quicksand, water is usually present in ample quantities, yet owing to the extremely fine particles of which the quicksand is composed, its presence as a water-bearing soil is highly undesirable.

Flowing Wells.

—Flowing wells are obtained in places where water is confined in the earth, under sufficient pressure to lift it to the surface, through an opening made to the water-bearing stratum. These are known as artesian wells, from the fact that they were first used in Artois (anciently called Artesium) in France. In order that water may have sufficient head to lift it to the surface, it must be confined under impervious clay or other bed of earth, and with its source at a level considerably higher than its point of exit. The source of supply for flowing wells is often at a great distance. Because of the fact that flowing wells are shut off from the surface by an impervious layer of earth, the possibility of pollution from the surface is effectively prevented. Any contamination of the water must come from a distance and enter the water at its source. As pollution rarely extends through the ground to any great lateral distance, artesian waters are seldom polluted. The water from artesian wells often is heavy with mineral matter and in many cases is unfit for drinking on that account.

CONSTRUCTION OF WELLS

Wells are constructed by different methods, depending on the character of the soil in which they are sunk. Their excavation[139] is usually accomplished by one of three general methods: by digging; by driving a pipe into the earth until it penetrates the water-bearing stratum; or by boring a hole with an enlarged earth auger, into the water-bearing soil. Artesian wells are made by drilling with a device suitable for making a small and very deep hole.

Dug Wells.

—In shallow wells the water seeps through the soil from local precipitation. Deep wells are those from which the water is brought to the surface through an impervious geologic formation, as a bed of clay or rock, and from a depth greater than that from which water may be lifted by atmospheric pressure. The fact that a deep well originates from a source that entirely differs from that of the shallow well accounts for the difference in chemical composition which frequently exists in the water from the two types of wells in the same neighborhood.

The form of the dug well is generally that of a cylindrical shaft 4 feet or more in diameter and of depth depending on the location of the water-bearing stratum. Where the character of the soil is such that the seepage is slow and the water does not flow into the well as fast as the pump will remove it, the well must contain a considerable volume to supply the period of greatest demand. Wells of this kind are commonly walled with brick or stone to keep the sides in place and to prevent the entrance of surface waters. The top of this curb should be brought above the surface of the ground and should be made water-tight to prevent the entrance of surface waters. The space around the curb, at the surface, should be graded to drain the water away from the well. There should be no chance for the water to collect in pools about the well; it should be conducted away in a gutter to the place of final disposal. The well should be covered with a platform of concrete or planking which will allow no water to enter from the surface.

Wells of this order are sometimes dug to great depth before the water-bearing stratum is encountered; this may sometimes be reached only after a great amount of expense and labor. The historic Joseph Well, near Cairo, Egypt, is an open shaft, 18 by 24 feet in area, sunk through solid rock 160 feet.

Open Wells.

—Open wells have long been condemned as insanitary. The familiar open well of the “Old Oaken Bucket” type[140] is an inviting receptacle for the deposit of all manner of refuse, which once inside remains until it is disintegrated. These wells become the final resting place of many small animals and all manner of creeping things, in search of water. The open top receives wind-blown matter in the form of leaves and dust, much of which is in the nature of polluting material.

The pressure and amount of flow from these wells is sometimes sufficient to permit the water being used for the generation of power. Small waterwheels are not uncommonly driven in this way and the power used for the generation of electricity for lighting and running small household appliances.

Driven Wells.

—In localities where the nature of the soil gives opportunity, wells are made by driving a pipe to the required depth. Wells of this character are usually made in places where the water-bearing soil is of sand or gravel. The pipe terminates in a sand-point such as that of Fig. 128. This sand-point is a perforated pipe with a pointed end, that facilitates driving. The perforations, as shown in the point P, form a strainer which allows the water to enter the pipe but prevents the sand from filling the opening.

In the use of driven wells, the water-bearing soil must be sufficiently open to allow the water to flow into the pipe as fast as the pump takes it away.

Bored Wells.

—In many localities the water-bearing stratum is of such nature as to give a ready flow of water but yet not sufficient to permit of the use of a sand-strainer; if, however, the opening is somewhat enlarged, the water will enter with sufficient rapidity to supply a pump. In such cases bored wells are quite generally used. They are made by boring a hole of the required size with an earth auger. These wells are made of any size up to 2 feet in diameter. They are often called tubular wells because[142] they are lined with iron tubing or tile, to prevent the earth from refilling the hole.

Cleaning of Wells.

—Very few dug wells are so constructed as to exclude dust and washings from the ground. It is, therefore, necessary that they be occasionally cleaned. Accumulations from these causes may be sufficient to hinder the entrance of the water to the well and thus lessen its capacity.

PUMPS

Pumps for lifting and elevating water are made of both wood and iron in almost endless variety; but for domestic purposes they are of two general types—the lift pump and the force pump—which include features that are common to all. The lift pump is intended for use in lifting water from low-head cisterns and wells, the depth of which is not beyond the head furnished by atmospheric pressure. The force pump performs the work of a lift pump and in addition forces the water from the outlet at a pressure to suit any domestic application. These pumps are made by manufacturers in a great variety of forms, but the essential parts are the same in all pumps intended for a single purpose. The principle of operation is the same in all pumps of any type. The difference in mechanism of pumps intended for the same purpose is only in the form and arrangement of the parts.

The Lift Pump.

—The kitchen pump is an example of the lift pump. It is universally used for household purposes where water is to be raised from cisterns, etc., and is most commonly made[145] throughout of cast iron. Fig. 129 illustrates one form, sometimes called the pitcher pump, because of the slight resemblance to the article. It frequently carries the name cistern pump from the fact that it very generally is used to lift water from cisterns.

Although water may be raised 34 feet with a theoretically perfect pump and with a barometric pressure of 30 inches the actual limit is much lower. In use, 20 feet is probably about the limit and 10 feet or less is that of common practice. A pump that requires “priming” would raise water 15 feet with considerable difficulty for reasons that will appear later. In Fig. 129 is shown a sectional view of the working parts of the kitchen pump, the action and general form of which apply to any lift pump. The body of the pump contains a cylinder, in which closely fits a piston P, containing a valve A. At the bottom of the cylinder is an additional valve B. The piston and two valves constitute the working parts of the pump. The water is lifted through the pipe S, and is discharged at D.

The action of the pump is as follows: With the piston at the bottom of the cylinders and with no water in the pump, the handle is forced down, which action raised the piston. In so doing the air below it is rarefied. The reduction of pressure due to the rarefication of the air allows the water to rise in the pipe S correspondingly. After repeated strokes of the piston, the water reaches the valve B, which raises to let it pass, but immediately closes at the end of the upward stroke. When the space between the piston and the valve B is filled with water, each descent of the piston forces the water through the valve A; and when the piston is raised, the water is lifted out through the spout.

The valve A is a loose piece of cast iron, surfaced on the lower side to make good contact with the piston. The valve B is of cast iron fastened to a piece of leather by a screw. The leather[146] makes a joint with the valve-seat and furnishes an excellent valve for its use. In order to keep the plunger P tight in the cylinder, it is surrounded with a leather gasket. Should this gasket become worn, as it will in time, the plunger fits loosely in the cylinder and the pump will lift the water with difficulty, because of the leakage around the gasket. Should the valve B leak, the water will gradually run back into the pipe S, and the pump when left idle will lose its “priming.” The plunger and the valve B are the parts most likely to get out of order. If the gasket around the piston P is very much worn, and there is no water in cylinder, the pump will require priming before the water can be raised. If the pump contains no water and is left standing for a considerable time, the leather parts of the valve dry out and shrink; when the pump is again put into use, the valves will fail to work properly, until the leathers are again water-soaked. Water is poured into the top of the pump until the cylinder is filled, and as soon as the leather becomes water-soaked and fills the cylinder, the piston will again perform its function.

The Force Pump.

—The house force pump is often used in place of the ordinary lift pump, when no other means is at hand for providing water under pressure. It furnishes a limited means[147] for lawn sprinkling and gives some degree of fire protection in isolated places. It may be made a part of the kitchen sink as shown in Fig. 130, by use of the attachment that appears in detail under the sink. This type of pump may be used in small water-supply plants, such as that of Fig. 143; or in connection with small pressure tanks for the same purpose. It differs somewhat in construction from the lift pump, in that it has no valve in the piston and is provided with a check valve and an air chamber for generating pressure to the discharged water.

Fig. 131 shows the essential parts of the force pump and furnishes a means of describing its operation. All force pumps possess the same parts and the operation described applies with equal force to all. A valve A is located in the bottom of the cylinder and the check valve B prevents the return of the water to the cylinder after it has been forced out of the pump. The action of the pump in raising the water is the same as in the lift pump but when the water fills the cylinder and the piston descends, the water is forced through the valve B and out at D. If the outlet pipe is slightly smaller than the opening in the valve B, some of the water will enter the air chamber C and compress the air. The pressure thus generated will immediately tend to force the water out and in course of ordinary pumping will send out a steady stream instead of the intermittent flow of the lift pump. Without the air chamber, the flow from this pump will be a series of pulsations that attain maximum force with each descent of the piston.

Tank Pump.

—The type of pump used with a water-supply plant will depend entirely on the amount of water that is used. If the supply of water to be provided is for only one or two people the house force pump such as that of Fig. 130 will suffice; but when a greater number of people are to be supplied, a force pump of the type shown in Fig. 132 is quite generally used. These pumps are made in a variety of patterns and are commonly[148] termed tank pumps. The one shown in the Fig. 132 is a double-acting force pump in that the cylinder receives and discharges water at each stroke of the piston. The air chamber is located at A. Directly beneath the air chamber is the valve chest in which are located the valves which regulate the entrance and discharge of the water. As used in the average domestic plant the cylinders are 3 or 4 inches in diameter.

WELL PUMPS

The pumps intended for raising water from wells are practically the same in construction as the house pump, except that they are intended to deliver a greater volume of water and sometimes to work under a different condition, as that of the deep well pump. Well pumps have, therefore, assumed certain standard forms that differ only in the styles of mechanism employed by different manufacturers.

The one shown in Fig. 133 furnishes a good example of a general-purpose iron pump which may be used either as a force pump or a lift pump. It represents also the general construction of a deep-well pump, where the water must be lifted from a level, below that at which a lift pump will work.

The piston and valves are enclosed in the cylinder C, placed below the surface of the water in the well. This cylinder also appears in section in the small drawing, showing the details of the valve. The operation of this pump is identical to that of the lift pump already described, but the addition of an air chamber gives it the necessary facility to produce a continuous flow of water. In order to prevent the air in the air chamber from escaping, the pump rod is surrounded with the necessary stuffing-box which is usually packed with candle wicking to assure a good joint. In deep wells the tube is elongated sufficiently to place the cylinder C below the surface of the water in the well. Such pumps are operated either by hand or by power.

The piece at the side of the pump is provided to drain the water from above the piston, as a precaution against freezing during extremely cold weather. The rod, when raised, opens an orifice[150] that leads to the inside of the pump and permits the water to drain into the well.

Pumps for Driven Wells.

—The method of constructing driven wells—that of driving a pipe into the earth to the water-bearing stratum of sand or gravel—requires a special end to prevent the pump tube from becoming stopped. In order that the fine material may not enter and fill the lower end of the tube, a sand-point is used, such as that shown in Fig. 128. It is made of perforated brass tubing and provided with a sharpened end to facilitate driving. The perforations act as a strainer that keeps out all but the fine particles which will pass the pump valves. Sand-points are made with strainers of various degrees of fineness to suit the different conditions of soils. These strainers may in the course of time become filled with particles of the soil that lodge in the perforations and the outside become so encrusted as to prevent the entrance of the water. In such case, the pipe must be pulled out of the ground and the point replaced by a new one. In Fig. 128 is shown a driven well with the sand-point in the water-bearing stratum. If the small particles of earth clog the strainer the pump will “work hard” and yield only a portion of the water the soil is capable of giving when the strainer is clear.

Where water is to be raised from a deep well, the cylinder with its piston is placed near the water and the tube and rod, as that of Fig. 133, connects the cylinder with the pump stock. After the water has passed the valve in the piston, it may be readily lifted to the pump stock. In this way water is raised from wells of great depth.

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Tubular-well Cylinders.

—Tubular wells that are cased with iron pipe are provided with a special type of pump cylinder that admits of deep-well operation. The casing of the well being in place, the cylinder shown in Fig. 135 is forced down the casing to its proper place, the spring S holding it in place until it is firmly secured. A special seating tool is now lowered into the casing and attaches at T to the coupling; as the tool is turned, rubber packing R is expanded, locking the cylinder firmly to the casing. This makes a complete pump cylinder, which with the piston P in place is operated as any other pump.

RAIN-WATER CISTERNS

Cisterns for the storage of rain water have been used from the time immemorial and are constructed in a great variety of forms. For household use they are often made in the form of wooden or metal tanks, either elevated or placed in the basement; the greater number, however, are of the underground variety made of brick or concrete.

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Wooden cisterns are made by manufacturers in different sizes and shipped to the user “knocked down;” that is, they are taken apart and the staves, bottom and hoops are shipped, packed in small space to save space in transportation. Under some conditions they give good service but are apt to leak at times and require attention on that account. In damp basements they give out the disagreeable odor of damp wood.

Tanks made of galvanized iron are much used as cisterns for temporary use. They are inexpensive and give good service but are short-lived. Possibility of leakage is their greatest disadvantage. Underground cisterns are built either in the basement or outside the house. They are quite generally made jug-shaped, but are often constructed of concrete in square and rectangular form. When built of brick the walls are often made of a single course, but walls made of two courses of brick are considered better practice. The walls and floor are made water-tight by plastering with an inch or more of cement mortar.

When cisterns are made of concrete, the floor should be put in 6 inches in depth and as soon after as possible the walls are put up. In good construction the walls are 8 inches in thickness of concrete, made of 1 part good Portland cement, 2 parts clean sand and 4 parts crushed stone. If the cistern is square or rectangular in form the walls should be reinforced with woven wire or steel rods, to prevent cracking.

The curb of the cistern should extend above the surface of the ground sufficiently to prevent surface water from entering, and the top should be covered with a wood-lined sheet-metal cover to prevent freezing.

Filters.

—Unfiltered cistern water is not, as a rule, fit for drinking purposes because of pollution from dust and impurities washed from the roof, but for bathing and laundry work filtered rain water is greatly to be desired.

As rain water comes from the roofs of buildings, there is washed into the cistern a considerable quantity of dust, leaves, bird droppings and other polluting materials which contaminate and discolor the water. This foreign matter is not injurious for the purposes intended, but to render the water clear it should be filtered before using.

Filters for cisterns are quite generally made of soft brick laid in[153] cement mortar, the face of the brick being left uncovered. Fig. 137 illustrates a simple and efficient form of filter made of a single course of brick. A space one-fourth to one-third of the volume of the cistern is left for the filtered water. The opening at the top of the wall must be large enough to admit a man, for some sediment will collect even in the filtered water and the filter must be occasionally cleaned.

The filter shown in Fig. 138 is dome-shaped and built of brick. The water is pumped from inside the filter and the suction of pumping filters the water as it is used. In this case the filtering action is accelerated by reason of the reduced pressure inside the filter as the water is pumped. The chief disadvantage in this form of filter is the small area exposed for the filtering action and the relatively greater amount of work required for pumping the water, due to the partial vacuum formed as the water is pumped.

The cistern in Fig. 139 is provided with a catch basin which acts as a strainer for removing leaves, etc., that would stain the water. It is made in the form of a concrete basin and partly filled with gravel. The filter in this case is formed by a depression in the cistern floor. A section of tile is placed on the floor,[154] and around it is filled the filtering material of gravel and sand. Filters of this kind are often filled with charcoal or other materials that are expected to purify the water. They are usually inefficient because their value as absorbers of polluting agents is short-lived and unless the materials are frequently renewed they are valueless and sometimes a detriment to rapid filtration.

THE HYDRAULIC RAM

In places where its use is possible, the hydraulic ram is a most convenient and inexpensive means of mechanical water supply. It is simple in construction, requires very little attention and its cost of operation is only the labor necessary to keep it in repair. Whenever a sufficient supply of water will admit of a fall of a few feet, the hydraulic ram may be used as a pump for forcing the water to a distant elevated point, where it may be utilized for all domestic purposes. The water may be used directly from the ram or stored in an elevated tank as a reserve supply; or accumulated in a pressure tank, where additional pressure is required.

The hydraulic ram has been used since 1796, when it was invented by Joseph de Montgolfier. The principle of its operation[155] is that of the utilization of the energy of flowing water. The running water is made to give up a portion of its momentum to elevate a part of the water, and transport it to a considerable distance. If the source of supply and the fall is sufficient, almost any amount may be elevated and carried to a great distance. Large rams are sometimes used as a means of water supply for small towns. In the use of the double-acting ram, one source of water may be used to operate the ram and water from an entirely different source may be delivered. It sometimes happens that a muddy stream and a clear spring are so located, that the water of the stream can be utilized to furnish the energy for conveying the spring water to a point where it is desired for use. This is accomplished by the double-acting ram in a most efficient manner.

Single-acting Hydraulic Ram.

—Fig. 140 represents the installation of a single-acting hydraulic ram, placed to take water from a spring E, and deliver it to an elevated tank at the house on the hill.

In case the ram must be located at a considerable distance from the spring in order to attain the required fall, a standpipe D—slightly larger than the supply pipe—is used to take advantage of the full force of the water. In long pipes, the friction of the flowing water absorbs a considerable amount of the energy of flow and a standpipe, located as indicated at D, in the picture, will assure the full force of the flowing water in the ram.

The ram is commonly placed in an underground pit as protection from freezing during cold weather, and a drain from the bottom of the pit conducts the waste water away. The supply[156] pipe or drive pipe B and delivery pipe C are buried underground below the frost line as a protection from freezing.

In Fig. 141 a sectional view of the ram shows all of the working parts. The air chamber G is shown partly filled with water; the impetus valve D is that part of the ram which checks the flow of the running water and forces a part of it through the valve E, at the bottom of the air chamber.

When inactive the valve D stands open and as the water enters from the pipe A, it flows through the valve to the waste pipe but as soon as the full force of the water bears on the valve it will suddenly close. This sudden stop of the flowing water will lift the valve E, and the energy of flow, due to its sudden stopping, will force some of the water into the chamber G. As this action occurs the upward pressure against the valve D is released and it reopens but immediately closes again as the water begins to flow. This process is kept up, each closure of the valve sending a little water into the air chamber. As the water gradually fills the air chamber, it is subjected to the same action as was described in the pressure tank, the air above the surface being compressed and the pressure developed in the space G forces the water out through the delivery pipe where it attains a force that is a factor of the height of the original fall.

The air in the chamber G, is subject to the same conditions[157] of loss as that of the pressure tank, and to be assured of a supply to give pressure to the water, some air must be carried into the chamber with the water. For this purpose the valve F provided. After the chamber is partially filled, there occurs a reaction in the flow of water at each closure of the valve, which causes a little air to be drawn in through the valve F with each impulse. This air bubbles up through the water and enters the chamber where it assures an elastic cushion for closing the valve E.

The flow of water from the supply pipe is regulated at H by a nut on the stem of the impetus valve which permits its regulation. Closing the valve slightly causes a less supply of water to be delivered; opening the valve wider gives a greater supply.

The Double-acting Hydraulic Ram.

—The diagram of Fig. 142 illustrates the working principle of the double-acting hydraulic ram mentioned above; where the water from a muddy stream is used to drive the ram and that from a separate source, as a spring is delivered.

The construction of the double-acting ram is similar to the single-acting ram, but a separate pipe S discharges spring water directly below the valve which acts just as though it had entered at the drive pipe. The ram in this case is receiving water from the drive pipe D, which operates the valve and furnishes power for elevating the spring water. The spring water enters the ram through the pipe S, to keep the space T filled, directly under the valve. The water which enters the air chamber is, therefore, only that from the spring.

A standpipe is arranged as shown in the figure, with a check[158] valve to prevent the water in the ram from being forced back into the spring water pipe after entering the ram.

DOMESTIC WATER-SUPPLY PLANTS

Until recent years, no thought was given to private water-supply plants, in any except the more pretentious residences. It was formerly supposed that the cost of machinery and installation of such plants prohibited the use of a water system in the average home. As an item of expense in building, a satisfactory water-supply system may be installed at a lower cost than is paid for plumbing and bathroom fixtures.

In recent years much attention has been given to the design of small water-supply plants for isolated homes, such as are required for suburban and rural dwellings, with the result that the necessary apparatus to suit any conditions may be obtained of any enterprising dealer.

The degree of completeness with which the plant is to be arranged will depend on the funds to be expended, but in the most modest dwelling some form of water-supply plant is possible. Where opportunity is given to make the plant complete, its appointments of construction may be elaborated to almost any extent. A suburban or country residence may be made as perfect in point of toilet, kitchen and laundry conveniences, as where city water and sewer service are available. The water-supply plant may be operated by hand or by power, and if so desired may be made completely automatic in action.

Gravity Water-supply Plant.

—In point of simplicity, the plant shown in Fig. 143 represents a water system that answers every purpose of a cottage and yet is only an elevated tank for storage of water, combined with a house force pump. The tank in this case may be made of wood or metal and is open at the top. The water is sent into the tank by the pump, and gravity furnishes the force for carrying it to the fixtures in the kitchen and bathroom.

In using a tank of the kind shown in the drawing, provision should be made for the possibility of leakage. This is arranged for by having the tank set in a shallow pan, so constructed that in case of accident the water may be carried away without doing[159] damage. This type of plant is not usually employed in cold climates, unless some provision is made to prevent the water in the tank from freezing. Tanks of this kind are sometimes used in cold climates but a much more desirable plant for the purpose is described below. In Fig. 143 the water from the cistern W is raised by the pump P, which also forces it into the tank above the kitchen. The gravitational force given the water, because of its elevated position is all that is necessary to carry the water to the fixtures in the bathroom and kitchen sink. As shown in the drawing, it furnishes a complete water system that will perform all of the requirements of water distribution for a small family.

The pipes from the range boiler are attached to the water heater, which forms a part of the kitchen range as explained on pages 116 to 120. It receives the supply of cold water directly from the tank through the pipe marked C, and the hot water from the range boiler is supplied through the pipe H. Cold water is also taken from the tank directly to each of the cold-water taps.

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The pump P is a house pump, such as is shown in Fig. 130. It is a small force pump, designed to suit the conditions of domestic use and is made to send water into the sink or into the supply tank as desired.

Pressure-tank System of Water Supply.

—The water-supply plant shown in Fig. 144 is another simple construction, somewhat more elaborate than the last, so arranged that the danger of freezing is practically eliminated. This is a simple pressure-tank system in which a tightly built metal water tank takes the place of the elevated tank of the previous figure, and a tank pump is used for lifting and giving pressure to the water. It is a more complete plant than the first and intended to accommodate a larger dwelling. The drawing shows all of the fixtures and connecting pipes that are required in the average home. It shows all of the appliances for connecting the pressure tank and range boiler with the wash trays in the basement, with all of the fixtures in the bathroom and with the fixtures in the kitchen sink. The range boiler is the same as those previously described and connected to the heater in an identical manner.

The original source of supply in this case is a cistern, sunk below the basement floor. The water is lifted from the cistern by the pump and forced into the pressure tank through a pipe near the bottom where it furnishes the supply for the house.

The pressure tank may be of any size to suit the requirements of the house and may be placed in either a vertical or horizontal position. It is sometimes galvanized, as a precaution against rust, but this is not a necessary requirement. The pipe which conveys the water from the pump connects with the tank near the bottom. As the water enters, the contained air above its surface is compressed into smaller and smaller space. The pressure that is developed by the compressed air furnishes the force by which the water is driven out of the tank and through the distributing pipes to the various parts of the system.

If the air in the tank when empty is compressed to one-half its original volume, then the gage pressure will be about 15 pounds to the square inch; if the air is compressed to one-third its original volume, that is, when the tank is two-thirds full of water, the gage pressure will be about 30 pounds to the square[161] inch, which is enough to supply water at any point of a two-story building with ample force. By pumping more water into the tank, a pressure of 50 or 60 pounds may be obtained without difficulty; but 40 pounds is generally sufficient for all the demands of a house plant. This is an application of the Boyle’s law which as stated in text books of physics is: “The temperature remaining the same, the pressure on confined gas varies inversely as its volume.” As the volume of such a confined body of gas is made smaller, the pressure increases in like ratio. The desired pressures are easily attained with a hand force pump such as is shown in the drawing.

The gage-glass G on the side of the tank is intended to show[162] the height of the water in the tank at any time, and the pressure gage attached to the supply pipe shows the amount of pressure sustained by the water.

The Pressure Tank.

—The water leaves the tank by a pipe attached near the bottom and branches to supply each fixture, to which the water is to be conducted. In the drawing, the pipe may be traced from the point where it leaves the tank to the various fixtures. The cold-water pipe terminates at the range boiler, for at that point the hot-water system begins. The range boiler is connected by two pipes to the water heater in the kitchen range. The water heater is a part of the fire-box of the kitchen range and so long as the fire is kept burning, water is heated and stored in the range boiler. Where the house is furnace-heated, the furnace fire is sometimes utilized for heating the water by use of a coil of pipe above the fire and which may take the place of the range heater. Various other means are also employed for heating the water as described under range boilers. In Fig. 145 is shown a nearer view of a pressure tank with the pump attached. The pump is in this case identical in its action to the one shown in Fig. 132, but differs slightly in mechanical design. The drawing shows the gage-glass G, for indicating the height of water; the pressure gage P, which indicates the pressure to which the water is subjected; the attachment of the supply pipe S, and the delivery pipe D. The water tap T is provided to draw off the water when the tank is to be emptied.

In operation, the air in the pressure tank furnishes the force which sends the water through the pipes to the various points, and forces it through the taps at the desired rate. If for any reason the air in the tank escapes, the propelling force is destroyed. This may occur by reason of absorption of the air by the water, due to the pressure to which it is subjected; or to[163] small air leaks that may develop in the joints, which allow the air to escape. To overcome the possibility of these occurrences, arrangement is made whereby air may be pumped into the tank by the same pump as that which supplies the water. In this way, the air is introduced with the water, which bubbles up through it to the surface. If at any time the pressure in the tank is lost, it may be replaced by pumping air alone into the tank.

Power Water-supply Plants.

—Where the pump is expected to furnish water to any considerable amount beyond that for household use, it is desirable that the plant be power-driven. If the work of watering stock, lawn sprinkling, etc., is intended, the tank and pump must be enlarged to suit the desired amount of water, and a gasoline engine, windmill or electric motor will be used for power. Where local conditions will permit, a hydraulic ram may be substituted for the pump and the pressure tank used for additional pressure and storage.

Fig. 146 shows a plant in which the pump is driven by a gasoline engine. In the figure, the engine E is shown connected by a belt to a speed-reducing device or “jack,” marked J. The object of this machine is to reduce the speed of rotation and charge it to the required motion for operating the pump. The[164] jack is connected to the pump by a rod attached to a large gear, so as to produce the desired crank motion; and the opposite end of the rod is attached to the pump handle. The rod may be detached at any time and the pump worked by hand.

Electric Power Water Supply.

—Fig. 147 shows another type of power plant in which an electric motor operates the pump. In this style of plant, the pulley on the electric motor M is connected by a belt to the large wheel W, from which the crank motion is secured for driving the pump P. This machine is provided with an automatic starting and stopping device, which automatically controls the supply of water in the system. Whenever the pressure in the tank falls to a certain point, the change of pressure produced on the diaphram valve A starts the motor, and the pump sends water into the tank until the pressure in the tank again reaches the amount for which the valve is set, at which time the valve disconnects the electric contact to the motor and the pump stops working.

As shown in the drawing, the large tank receives its supply of water from the well and aside from providing a reserve supply furnishes power for pumping cistern water. The water from the large tank is piped into the house for use as required, and from the same pipe is taken a hydrant for lawn sprinkling; in addition, this water is piped to the barn where it is used for watering stock. A branch of the same pipe is intended to operate a water lift, which in turn furnishes the house with soft water from the rain-water cistern for bathing, laundry, and kitchen purposes.

The Water Lift.

—The water lift is a combined water engine and pump, the motive power for which is the pressure from the[166] well-water tank. The soft water, pumped by the water lift, is stored in the smaller pressure tank marked Soft Water Pressure Tank in the drawing, and furnishes a supply for the purposes mentioned. The water lift is so constructed that when the pressure in the soft-water tank equals the pressure in the well-water tank, the lift will stop working and will not start again until water has been drawn from the taps. Whenever water is drawn from any part of the system, the pressure will be reduced and the lift will immediately begin pumping more water and will continue until the pressure of the two tanks are the same. The system is entirely automatic, each part depending on the power originally supplied by the windmill. The plant could be just as successfully operated by substituting a gasoline engine or other source of power for the windmill. The machinery for such a plant is not at all complicated neither is it difficult to manage, yet it is complete in every particular and furnishes an almost ideal arrangement for a country or suburban home.

In order to be assured of a supply of water over periods of atmospheric quiet, the well-water tank must be sufficiently large to supply water for 3 or 4 days; but in case of emergency water may be pumped by hand.

A nearer view of the water lift is shown in Fig. 149. In the[167] figure, the right-hand cylinder with its valve V is the water engine which furnishes the power for operating the pump, enclosed in the left-hand cylinder. The water pressure of the main supply furnishes the energy which drives the engine, the piston rod of which is attached to the pump piston. The engine receives its supply of water through the pipe marked Inlet and the waste water is discharged to the sewer by the waste pipe on the opposite side of the cylinder. The operation of the lift is governed by an automatic regulator which so controls the engine that it starts pumping whenever the pressure in the system falls to a certain point. The regulator marked Adjustable Regulator in the drawing may be adjusted to suit the water pressure desired in the distributing system.

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CHAPTER VIII
SEWAGE DISPOSAL

The disposal of sewage, in a convenient and sanitary manner is a problem of serious importance in the equipment of isolated dwellings with modern household conveniences. The manner of heating, lighting and of water supply are questions of selection among a number of established systems, but the problem of sewage disposal must in a great measure be determined by local conditions. Unless the natural surroundings are such as will permit sewage to be emptied directly into a stream of considerable volume, the problem of its safe disposal becomes one of serious importance.

Sewage is understood to mean the fluid waste from the kitchen, toilet and laundry and has nothing whatever to do with garbage. Sewage disposal has to do with conducting away the house waste and disposing of it in a sanitary manner. Sewage disposal does not necessarily have anything to do with sewage purification; although a sewage disposal plant may be so constructed as to discharge a purified effluent, it usually is understood to have to do alone with its disposal in a manner that does not offend the aesthetic sense. A simple sewage plant is anything that will take the sewage away from the house in such a way as to produce no unsightly accumulations that will decay and produce offensive odors.

A sewage purification plant is one in which the raw sewage from the house drain is first liquefied, after which the liquid is passed into a filter where it undergoes a process of bacterial disintegration and the organic matter reduced to the inorganic state, where no further change is possible. The water which flows from such a filter is clear and sparkling, and is often taken for spring water. The degree of purification given to the sewage will depend on the style of filter and the length of time necessary for the water to pass through it.

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Sewage is composed of organic matter in a fluid or part fluid condition, contained in a large volume of water. It is not usually the dark, heavy, foul-smelling fluid that is imagined by many, but a turbid liquid possessing only a few of the qualities usually ascribed to sewage. Under favorable conditions practically all of the organic matter will be readily dissolved and the sewage will become entirely liquid.

As a liquid, the raw sewage is in the most favorable condition for rapid decay and if left standing in the air it soon develops properties that render it highly objectionable.

The decay of all organic matter is a process of disintegration that ultimately ends in the elements from which it came. In the disposal of sewage, the aim is to permit this disintegration to take place under conditions that will be least offensive to the aesthetic sensibilities, and in some cases to render it free from harmful properties should there be present the bacteria of communicable disease.

The successful disposal of sewage from cities is accomplished under a great variety of conditions. It is much easier to arrange for sewage purification on a large scale than in a small way. The reason for this is that in the care of a city the sewage-disposal plant is under the supervision of a competent person, whose business it is to see that the conditions are kept at the highest efficiency. Private plants are left almost entirely without care, until they fail from causes that are usually preventable. Sewage may be successfully purified under a great many conditions, but no type of plant has as yet proven itself successful that does not receive intelligent attention.

The most successful of small sewage disposal plant is the septic tank system alone or in connection with an adequate form of bacterial filter. Cesspools are not to be countenanced by people of intelligence. The cesspool has been so universally condemned by authorities on sanitation, that all intelligent people look upon it as a thing filthy beyond description. Although the septic tank is little more than an improved cesspool, the condition under which it acts is entirely different from that which takes place in the latter and with care and watchfulness, it may be made to work to a degree of perfection that is surprising. The one great cause of the[170] failure of small sewage-disposal plants is the lack of proper care.

The process of sewage purification as now practised in the most successful plants is largely mechanical, but bacterial action plays a part of great importance in the completion of the process. It consists of two stages: the tank treatment, in which the sewage is liquefied; and the process of filtration where the liquefied sewage—commonly called the effluent—from the septic tank undergoes a process of filtration and bacterial purification.

The Septic Tank.

—The septic tank alone, as used for sewage disposal, is often termed a sewage purifying plant, when in reality it is only intended to change the sewage into a form in which it can be readily carried away. The word septic means putrifying, and when applied to sewage disposal it furnishes a convenient term but has nothing to do with purification. The septic tank furnishes only the first stage of the purifying process, and although its effluent may be clear and possess little odor, it is nevertheless unpurified. The septic tank discharges an effluent of more or less completely digested sewage, instead, as in the cesspool, of permitting it to remain a constantly festering mass, to be slowly absorbed by the earth.

The sewage is first collected in a tank of sufficient size to contain the discharge from the house for 24 hours. In the process of digestion which the sewage undergoes while in the tank, it is rendered almost entirely liquid; at the same time it is acted upon by the bacteria that are developed, and that tend to reduce the sewage to its elemental form. The effluent liquid which passes out of the tank is almost colorless and possesses relatively little odor.

The tendency of the change which takes place in the tank is to nitrify the organic matter but under ordinary conditions the action is not fully complete. The effluent sometimes undergoes but little change except to be reduced to a liquid. If the effluent is now allowed to flow into a ditch where it will stand in pools, further putrification will take place with its resulting annoyance. In case the septic tank is to be used alone, the effluent should be conducted to a stream for final disposal. A septic tank must be built to accommodate a certain number of people and of sufficient size to take care of the entering sewage. The action which goes[171] on in the tank will render the contents almost entirely fluid, and under good conditions the sewage will be completely digested. When working properly, a thick scum will form on the surface, through which filters the gases that are liberated in the process of disintegration. The formation of the scum is an indication that the filter is doing its best work. Should the tank be required to take care of more sewage than it can conveniently handle, the scum will not form and the effluent will be turbid because of the undigested matter.

The change that takes place in the sewage while it remains in the tank is first that of being liquefied and then disintegrated by bacterial action. That such a change does take place is evidenced by the residue that is found in the tank in the process of cleaning. This is a black granular substance, composed mostly of humus and commonly known as sludge. The amount of accumulated sludge is relatively small, and the operation of cleaning is not necessary more than twice a year and is not the disagreeable task one might suppose.

The Septic Tank With a Sand-bed Filter.

—In places where the use of the septic tank alone is not possible, it sometimes happens that the natural conditions are such as will permit the effluent to be drained directly into the soil. With such a condition, the effluent goes into a filter bed composed of gravel or other loose material, where it undergoes still further bacterial action and if the process is complete, the water which comes from the filter bed is clear and odorless. Under good conditions it is clear sparkling water and contains but a small amount of impurities.

Septic tanks are made in many forms but that illustrated in Figs. 151 and 152 is commonly used. In Fig. 151 the tank is shown in position to receive the sewage from the house drain, where it is to undergo the first treatment and then to be conducted to a filter bed made of porous tile, set in loose soil. The tank is shown in detail in Fig. 152. It is a cemented brick cistern with an opening to the surface that contains a double cover as a protection during cold weather. A brick partition divides the tank into spaces G and H, that contain volumes that are to each other as 1 to 2. The tank is of such size as will hold a volume of sewage equal to 24 hours’ use; that is, it is expected[172] that any portion of sewage will remain in the tank for that length of time. The sewage enters at A, in such a way as will give the least disturbance of the liquid of the tank. An opening C allows the liquid to pass from H into G, where any additional sewage entering H will displace an equal amount in G, which will pass out at B to the filter bed. The partition D is high enough so that the scum that forms on the surface will not pass directly into the space G. The entrance and exit pipes are made of vitrified sewer tile with the openings below the surface.

As the sewage enters the tank A, a considerable portion will sink to the bottom, while some will float to the top where a thick scum will gather. By far the greatest portion of solids will be readily dissolved in the water and the remainder will be still further reduced to liquid form by bacterial solution. The process of disintegration that goes on evolves a considerable amount of carbon dioxide and ammonia which filters through the scum. The process that now goes on in the tank is that of liquefying the organic matter and changing it from organic to the inorganic state.

The bacteriologist recognizes in the process of sewage disintegration the work of two classes of bacteria, the aerobic or those[173] bacteria that work by reason of air and do their work only in its presence and the anaerobic or those that work in the absence of air. In the action of the sewage-disposal plant both kinds of bacteria are at work. If, in the final stage where the sewage passes into the filter, air can be carried into the earth the action will be hastened.

It is evident that, since the sewage entering the tank is almost entirely dissolved, under ideal action this system would give very little trouble, but actually as the sewage enters the tank the disturbance caused by the incoming water forces some of the undigested matter into the outlet and being carried into the filter bed it will be deposited at the first opportunity. This will cause the filter bed to fill up with undigested sewage at the point nearest the entrance, and in course of time it will stop the pipe because of this accumulation.

To avoid such an occurrence, tanks have been built in which an automatic siphon discharges the effluent whenever a certain quantity has collected. Such a tank is shown in Fig. 153. With this arrangement, the sewage enters the first tank at A, and passes[174] into the second tank at B. At S is shown an automatic siphon, so made that when the effluent has collected to the height of the water line, the siphon automatically discharges the contents of the tank. This is known as a dosage tank because periodically a dose of the effluent is discharged into the filter bed. The volume discharged is sufficient to fill the greater portion of the bed, and force out the air in the loose soil. As the water filters from the bed the air is drawn in to take its place and gives the bacteria which work in the presence of air an opportunity to do their work. The work done by this filter bed is first to filter out any suspended matter carried in the effluent which will lodge on the surface of the filter material and then to undergo the slow process of integration, and to permit the oxidation of the dissolved sewage. If this matter is deposited faster than it disintegrates then the filter will fill up and finally refuse to work.

The Septic Tank and Anaerobic Filter.

—In places where the use of the simple septic tank is not possible and where the character of the soil will not permit of a natural sand-bed filter, an anaerobic filter may be constructed through which to pass the effluent from the septic tank.

The anaerobic filter is one in which anaerobic bacterial action is given opportunity to reduce the organic matter in the sewage to its elemental condition. The filter may be constructed in any form that will permit the process of filtration to be carried out in a way that will afford good anaerobic action. The extent to[175] which the purification is to be carried will determine the form and size of the filter.

In Fig. 154 is shown such a plant, where a combined septic tank and anaerobic filter discharges its effluent into a filter ditch in which the purifying process is continued through a bed of gravel of any desired length. The figure illustrates a plant that was designed for a country residence. The septic tank and anaerobic filter are located relatively as shown in the drawing, the filter ditch following the course of a roadway. The water is finally discharged into a little stream, where it mingles with the water from a spring, and flows through a meadow.

The septic tank in Fig. 154 is quite similar in construction to the others described except that a section of sewer tile takes the place of the brick wall between the two parts of the tank. The opening O, through which the effluent is discharged, is located a little above the center of the tank.

The anaerobic filter is a tank, rectangular in cross-section, made with brick walls and cemented on the inside. The effluent from the septic tank enters the anaerobic filter in a chamber, that is separated from the main tank by a wooden grating against which rests the filter material. As indicated in the drawing, the bottom is filled with coarse material; stones or broken tiles[176] about 4 inches in diameter. Above this is a layer of material about 2 inches in diameter and above that another layer of 1-inch material; the top is made of gravel. This forms the anaerobic filter, in which takes place the bacterial action away from the presence of air. The interspaces in the filter material allows the effluent from the septic tank to seep through and deposit the particles of matter held in suspension. The arrangement is such as is best suited to the anaerobic action. Here, shut away from the light and air, the organic matter in the effluent undergoes disintegration just as would happen in the earth.

It is evident that some of the matter that should remain in the septic tank and be removed as sludge will be carried into the anaerobic filter. This will, of course, form an insoluble deposit that will accumulate and in the course of time the filter will become clogged. It should be expected that such a filter will ultimately need renewing, for this reason the top is made of a slab of reinforced concrete that may be raised to allow the removal and refilling of the filter material.

The automatic siphon discharges the water from the chamber S, whenever it fills. The discharged water from the siphon is conducted into a drain tile, placed in a ditch filled with gravel or other loose material, which serves as an additional filter and in which the water undergoes a still further purification. This filter ditch is constructed as indicated in longitudinal section. The water from the siphon enters the tile C and seeping through the filling is drained away in the tile shown at D.

The tiles are not set close together, but the joints are left open and covered by pieces of broken tile as shown in H. This is to prevent the filter material from entering the tile and thus stopping the ready flow of the water.

The filter ditch of the plant will be constructed according to the contour of the ground and will follow the natural drainage. The course of the ditch—if it is desired to use one—will accommodate itself to the character of the ground. The final discharge of the water will be determined by the natural drainage.

That a plant of this kind will work perfectly when new is is beyond a doubt but that it will continue indefinitely to give perfect satisfaction is not reasonable to expect. The septic tank will require cleaning, probably once a year. The anaerobic filter[177] will require renewing at intervals, depending on the amount of sewage the filter is required to take care of and the rate at which the plant is worked, probably once in 4 or 5 years. If the septic tank is of insufficient size to readily digest the sewage, the accumulation of sludge in the anaerobic filter will be greater than should occur.

It would be only reasonable to suppose that the siphon will sometimes refuse to discharge. Even though it is an automatic siphon, circumstances may cause it at times to fail to act. For this reason the manhole is placed so that the siphon may be inspected and repaired, should it be necessary. It must not be supposed that once such a plant is in place that all of the work is over. The success of a good sewage-disposal plant of this kind demands eternal vigilance.

In the level areas where the possibilities of natural drainage is not good, it sometimes occurs that plants such as those described are not permissible. To overcome such conditions the plant in Fig. 155 represents an installation where the effluent is carried several hundred feet through a drain tile before it is finally discharged into an outlet. This plant is made up of two separate tanks, the first acting as a septic tank, while the second tank is a settling chamber. The water from the second chamber is[178] pumped by windmill power and discharged into a drain tile at the required height through which it is carried to the place of final deposit.

Limit of Efficiency.

—Much that has been written on the subject conveys the impression that the septic tank alone, used under various conditions, will eliminate disease germs and all offending features of sewage and render it a pure water with a small amount of residue remaining in the tank. That such is not the case is all too evident to many who have constructed plants expecting perfect results and have attained only partial success.

It is not reasonable that a plant giving satisfaction under the usual conditions could accomplish its purpose under stress of work. It is quite evident that the amount of sewage from any source cannot be constant. It is equally evident that the effluent from the plant cannot always be the same; but with reasonable limits of variation, a suitably designed tank ought to take care of the sewage from a house at all times and discharge an effluent that is reasonably clear and without offending odor.

It should be kept in mind that, as commonly used, the chief office of the septic tank is to do away with the things that offend the senses, and not to make an effluent that might serve as drinking water. It must also be kept in mind that if the disease germs enter the plant because of sickness in the house that there is every possibility that the germs will be in the discharged water.

The plant must be located as is directed by the natural surroundings but the drainage must be away from buildings and particularly from wells.

Small sewage plants are reasonably efficient and add immensely to the comfort and healthful conditions of the home. They are not perfect in their action but there is excellent reason to believe that the plant of ideal construction will yet be attained.

In a flat country where drainage is difficult, the form of plant must be modified to suit the prevailing conditions but some form of working plant can always be devised. Small plants do not give so efficient results as those of large size but they do very acceptable work. To do good service they must receive attention but the actual amount of labor they demand is small. Small sewage-disposal plants are not expensive nor difficult to construct,[179] and for the amount of labor and money expended they give returns that cannot be estimated.

In determining the character of plant to be constructed, in any particular place, local conditions will in a great measure decide the type to be used. The degree of purity to which it will be necessary to reduce the effluent will depend on the location of the plant and the means of final disposal. If the effluent can be run into a stream of sufficient volume, the septic tank alone will probably answer the purpose.

The septic tank reduces sewage to a liquid form which has some odor. It may be carried away in an open ditch which has good flow, but if allowed to collect in pools it will undergo further putrescence and be objectionable.

It may be possible to use a small creek for final disposal but one in which the effluent from a septic tank alone would be objectionable. In such a case the use of the septic tank combined with an anaerobic filter would probably give a permissible degree of purity.

With a plant composed of a septic tank and anaerobic filter, sewage is rendered almost free from odor and the effluent will not undergo further putrescence when collected in pools.

In many cases it is desired to purify the effluent still further, either because of lack of means for final disposal or because the effluent would contaminate the water into which it is discharged. In such cases the plant will consist of the septic tank, an anaerobic filter and a filter ditch or sand-bed filter. The effluent from such a plant will be clear sparkling water that might be mistaken for spring water.

The design and construction of sewage-disposal plants has been made a subject of investigation in a number of State engineering experiment stations. In addition, manufacturers of cement have prepared descriptive literature that is sent gratis on application. These bulletins contain detailed information as to the working properties and construction of private plants to suit the various conditions of disposal. The following is taken by permission of the Universal Portland Cement Co. from their bulletin on “Concrete Septic Tanks.”

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CHAPTER IX
COAL

Coal is of prehistoric origin, formed from accumulation of vegetable matter, supposed to be the remains of immense forests. In past ages the deposits underwent destructive distillation from great heat and was subjected to pressure, sufficient to compress it into varying degrees of hardness. Coal is composed of carbon, hydrogen and oxygen, with small quantities of nitrogen and varying amounts of sulphur and ash.

The coals from different geological formations vary in quality from the hard dry anthracites to the soft wet lignites, with the intermediate bituminous coals; all of which furnish fuels that when burned will produce amounts of heat, depending on their composition, the quantity of moisture contained and the conditions of their combustion.

Carbon, of which coal is principally composed, exists in different combinations, depending on the condition of its formation. Part of the carbon is combined with hydrogen to form hydrocarbon that may be driven off when heated, and which forms the volatile portion of the coal. The remainder of the carbon appears in the form of coke—when the volatile matter is driven off—and is said to be fixed. The fixed carbon and volatile constituents together make up the combustible.

Other ingredients of coal that require attention are the moisture, and the incombustible matter that forms ash. Moisture varies in quantity from as low as 0.75 per cent. in hard coal to 50 per cent. in lignite. The amounts of ash in different coals vary from 3 to 30 per cent. of the weights of the fuel.

The heating value of coals differs in amount by reason of the variable quantities of fixed and combined carbons, moisture and ash. Different coals are compared in value by the number of B.t.u. per pound of dry coal that can possibly be developed when burned, and with these factors are given the percentages of moisture and ash.

There are no distinct demarkations between different grades of[183] coal. The classifications are made because of their chief characteristics and they commonly are graded as anthracites, semi-anthracites, semi-bituminous and bituminous coals. These classes comprehend the most common commercial coals of the United States. Aside from those named are forms of coal that are occasionally found, such as graphitic anthracite, cannel coal, etc., and the various lignites.

The value of coal as a heat-producing agent is represented by the B.t.u. it is capable of turning to useful account. The price of coal should be based on the amount of heat it is capable of generating when burned. In considering the value of coal for any particular purpose, thought must be taken as to its characteristic properties, for coals that produce excellent results for one purpose may be very unsatisfactory in others. Soft coal containing a large percentage of volatile matter usually produces a great amount of smoke and unless carefully fired this will condense and form accumulations of soot that are objectionable. For reasons of this kind bituminous coals are often sold at a lower price than their rated heating value might indicate.

Anthracite or hard coal

possesses bright lustrous surfaces when newly fractured, that when handled do not soil the hands. It contains a high percentage of carbon, a small amount of volatile matter and little moisture. It is greatly in demand as a domestic fuel because it burns slowly with an intense heat, practically without flame and produces no smoke. It invariably commands a higher price than soft coal, but in heating value is not superior to the better grades of soft coal. In furnaces for house heating the use of soft coal often gives better satisfaction than hard coal.

The grades of hard coal found in the market will vary with the demand in any locality but those recognized by the trade are:

Hard coal of stove and chestnut sizes are those most commonly used for domestic heating, because they are well suited for[184] furnaces and heating stoves. Of the two sizes chestnut coal is most largely used and on account of the greater demand, the price for this size is usually somewhat in advance of the others; at the same time the smaller sizes—pea and buckwheat coals—are less in price for the same grade of coal. Under conditions that will permit their use the latter coals are an economical form of fuel.

Bituminous or soft coal

represents the chief fuel of commerce. The market prices of these coals are determined largely by reason of their reputation as desirable fuel. The variations in price depend on the physical qualities, rather than on the amount of heat evolved in combustion. The compositions of coals vary markedly in different localities and often in the same locality several grades are produced. It sometimes happens that from different parts of a mine the coal will differ very much in heat value.

Bituminous coals are roughly classified as coking and free-burning. The former is valuable for gas manufacture and for production of coke. The coking coals fuse on being heated, allowing the volatile portion to escape; and when the gas has been all distilled, the residue is coke. When used for gas making, the volatile portion forms the illuminating gas. When burned in a furnace, the gases from soft coal burn with a yellow flame and usually with considerable smoke. The classification of bituminous coals differ somewhat in the East from that of the West. Eastern bituminous coals are commonly graded:

Heat derived from coal—or any other fuel—in the process of combustion is due to oxidation. Combustion or burning is caused by rapid oxidation. When oxygen combines with[185] carbon in sufficient quantities, carbon dioxide is formed and at the same time heat is liberated. In burning fuel, if the carbon is completely oxidized and changed into carbon dioxide, the greatest amount of heat is produced. The required oxygen is furnished by the air, which through the dampers of the furnace regulates the rate of combustion.

Oxidation of Hydrocarbons.

—In the oxidation of hydrocarbons, as that of burning coal gas, the combination of the elements forms carbon dioxide and water. The presence of the water, formed in combustion, is often shown in the formation of moisture on the bottom of a cold vessel when placed over a gas flame. The same effect is observed in a newly lighted kerosene lamp, when the film of moisture forms inside the cold lamp chimney. As soon as the surfaces become heated the moisture is evaporated. Occasionally, the accumulation of moisture in chimneys, from this cause, is sufficient during extremely cold weather to form ice in the part of the chimney exposed to the outside air. Chimneys have been known to become so stopped by accumulation of ice from this cause as to materially interfere with the draft.

The fixed carbon of the coal, when oxidized, has a constant heating value of 14,000 B.t.u. per pound. The volatile hydrocarbons develop amounts of heat when burned, depending on their composition, and differ in coals from different localities. The heat obtained from the volatile part of coal depends on its chemical composition and differs very materially; it may be as high as 21,000 B.t.u. per pound, or as low as 12,000 B.t.u. per pound.

A high percentage of volatile matter usually indicates a fuel that will produce a large volume of smoke, which—unless the combustion is complete in the furnace—will deposit soot as soon as it is condensed, either in the chimney or in the outside air. The ash has no heating value, and the contained moisture has a negative heating effect, because considerable heat is required to evaporate and raise it to the temperature of the gases of the furnace. In burning fuel the moisture uses up the heat of combustion in proportion as it appears in the coal. The moisture is bought as coal but requires heat to get rid of it; so the percentage of water in coal should be considered very carefully.

It is customary in comparing the heating values of coals, to[186] state the proportionate parts of fixed carbon, volatile matter, moisture and ash as well as the B.t.u. per pound of dry coal. The heat value in B.t.u. per pound of fuel is usually obtained by burning samples in a calorimeter from which the heat per pound is calculated. The heat value of fuels used in power plants are often determined by careful tests of the amount of power derived for each pound of fuel burned in the furnace. This is done by weighing the fuel burned and measuring the water evaporated. The ashes are weighed and this weight together with the weight of moisture present is subtracted from that of the coal to determine the amount of combustible of the fuel. The final results are expressed by the number of pounds of water evaporated per pound of combustible and also the weight to water evaporated per pound of coal burned.

Semi-bituminous coal

represents a class between the hard and soft grades. It contains less carbon and more volatile matter than hard coal. It burns with a short flame with very little smoke and is valuable as a furnace fuel. The Pocahontas coal of West Virginia is an example of this class. Semi-bituminous coal is often called smokeless coal, because in burning it produces relatively little smoke. It will be noted in the table of heat values on page 192 that coal of this variety has high heat-producing properties. It is a very friable coal and for that reason is apt to contain considerable dust. As a furnace fuel it produces—when carefully fired—very satisfactory results.

When newly mined, lignite contains a large percentage of water, sometimes as high as 50 per cent. On account of this[187] large moisture content it has a relatively low calorific value, but when dry the amount of heat evolved per pound compares very favorably with soft coal.

Peat.

—As a fuel, peat has been used very little in the United States on account of the abundance of the better grades of fuel, but in many parts of the country it is used locally to a considerable extent. In peat bogs from which the fuel is taken, the peat is formed from grasses and sedges which in time produce a carbonaceous mass that becomes sufficiently dense to be taken out in sections, with a long narrow spade. The peat is then built into piles where after drying it is ready to be burned.

The desirability of wood as a fuel is chiefly that of reputation. It is usually considered that hickory is the ideal fire wood, dry maple a close second and that oak is next in desirability as fuel; following which are ash, elm, beech, etc., depending on the density of the wood. The price of wood per cord depends on the nearness and abundance of supply.

The actual heating values of different woods as determined by Gottlieb show that per pound of dry wood there is little difference in heat value between different kinds of hard woods, and that pine gives per pound the highest value of all. The table given below was taken from “Steam” published by the Babcock-Wilcox Co.

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In considering this table it must be kept in mind that the values are for dry wood per pound.

As given in Kent’s “Engineer’s Pocket Book” the weights of different fuel woods per cord (thoroughly air-dried) are about as follows:

The above values in pounds of coal may be taken to represent average bituminous coals. As given by Suplee’s “Mechanical Engineers’ Reference Book,” eight samples of coals representing bituminous coals from mines east of the Mississippi River give an average heating value of 13,755 B.t.u. per pound.

Charcoal.

—This is made from wood by driving off the volatile constituents; the residual carbon, which forms the charcoal is a fuel that burns without smoke or flame. Charcoal is made by piling wood in a heap, which is covered with earth. In the bottom of the heap a fire generates the necessary heat for distilling off the volatile matter. Charcoal holds to wood the same relation that coke bears to coal.

Comparative Value of Coal to Other Fuels.

—Until a comparatively recent time, coal has been sold by weight and reputation alone; but conditions are rapidly approaching, which will require it to be sold according to its composition and heating value. Among manufacturers and others using large quantities of fuel, the practice of contracting for coal by specification is becoming increasingly common. The determining factors are the amounts of moisture, ash, sulphur, carbon, and volatile matter the coal contains, as well as the size of the pieces and freedom from dust. In a few of the most progressive cities, coal dealers are required to supply coal for schools and other municipal uses, which has been subject to the approval of the City Engineer. The time is not far distant when dealers will be required to submit samples of all fuel, for sale to the public, to the examination of the municipal authorities.

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The following table of the heating values of various fuels is taken from Benson’s “Industrial Chemistry.”

British Thermal Units for One Cent from Different Fuels

Price of Coal.

—The value of coal as a fuel will depend on the amount of heat it is capable of producing when burned; its price should therefore be determined by the heating value per pound of fuel as purchased. Secondary determining factors in price are those of convenience of handling and the difficulty in burning the fuel such as the size and uniformity of the pieces, the formation of clinkers, smoke and accumulation of soot. Soft coals, containing a large amount of volatile matter, usually produce much soot and smoke and as a consequence sell for a lower price than coals that produce little smoke.

The selection of fuels will depend on the type of heating plant in use, whether by stoves or by furnaces. If by stoves, whether it is possible to use soft coal as a fuel. The automatically fed stove, of the base-burner type, are usually designed for the use of hard coal and in such stoves the use of soft coal would not be possible. Other stoves and furnaces are usually capable of burning soft coal with varying degrees of satisfaction, depending on the design and surrounding conditions.

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The following prices, from the local market, show the usual ratings of various fuels in common use. These prices vary with the locality and somewhat with the season. It is usually possible to purchase coal at some reduction in price during the summer months when the demand for coal is light.

The price of coal is determined in many localities by the distance from the sources of supply and the means of transportation. The fact that coals from all of the principal mining areas from Pennsylvania, west to Iowa, are sold at points in the Northwest for the same price, is due in greatest measure to transportation rates on the Great Lakes. The prices of Eastern coals at Duluth are such that in competition with Western coals they are sold at the same price as is shown by the table.

It is usually impossible for the average householder, or even the dealer, to determine definitely the exact locality from which his fuel is mined. Even when such information is obtainable, the quality is still in doubt, unless analysis is obtainable by sample. The data given in the following tables is such as will furnish a fair knowledge of the relative heating values of coals from the principal mining areas of the United States. The data was obtained from a considerable number of authorities but chiefly from the reports of the United States Geological Survey. The different items are not intended to be exact, they merely represent reliable average conditions.

The varying conditions of available heat and percentage of moisture given in the following table are such as to be of little use to those unaccustomed to problems of this kind, unless a systematic method of comparison is made of the different fuels.

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Approximate Composition and Calorific Value of Typical American Coals

The following table was prepared from the date of that preceding combined with the prices of various coals to be obtained in the local market. The table is intended to present a method of comparing the values of fuels from different coal areas. The consumer is interested to know the amount of heat purchased in the form of fuel. The table shows in the column headed “Heat per $1,” the number of B.t.u. purchased for $1 in coal; the number of available B.t.u. in the different kinds of coal may be taken as a relative comparison of their values as fuel.

The gas-coke in the table is that sold by the local gas company. The amount of moisture in this case is relatively high because of[193] the fact that the coke is stored in a yard exposed to the weather, where it absorbs all precipitated moisture. A less amount of moisture would give a higher value for the same fuel.

Semi-bituminous coal commands considerable favor as a house-heating fuel, because of the fact that it burns with much less smoke than bituminous coal. In available heat it is considerably above the Western bituminous coal and it sells at a price $1.50 higher per ton. The reason for the difference in price is not so much on account of its heating value, as because of relatively small amount of smoke produced in combustion. Other coals capable of producing more heat are sold at less price because of smoke and soot produced in burning.

Hard coal at $10.50 is the most expensive coal of all. The ratio of available heat units per $1 for hard coal, as compared with the best soft coal, is as 23 is to 35. This means that at the stated prices those who burn hard coal pay the additional price, because of the physical properties it possesses.

In constructing the above table, 100 pounds of coal was taken as a unit of comparison. The price per ton is that given in the table of local prices. The per cent. of moisture and the B.t.u. per pound of fuel was taken from table on page 192.

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In explaining the method by which the different items were obtained, it will be necessary to discuss briefly the condition of combustion and the heat losses that take place when fuel is burned.

The moisture in the fuel is the undesirable part, because it requires a large amount of heat to dispose of it. It is looked upon as so much water, that must be raised in temperature from that in which it is taken from the coal bin to the temperature and condition of vapor in which it passes into the chimney. When the fuel enters the furnace the water is heated to the boiling point. In changing temperature it absorbs 1 B.t.u. for each pound of water, through each degree of change. Suppose that, as in the case of Pennsylvania bituminous coal which contains 2.44 pounds of water to each 100 pounds of coal, the coal entering the furnace was at 50°F. To raise its temperature to the boiling point (212°F.) required a change of 162°. The 2.44 pounds of water raised this amount

162 × 2.44 = 395.28 B.t.u.

To change the 2.44 pounds of water, into steam at the atmospheric pressure requires 969.7 B.t.u. (heat of vaporization), practically 970 B.t.u. per pound of water. The heat required to vaporize 2.44 pounds of water is

2.44 × 970 = 2366.80 B.t.u.

The vapor is now raised in temperature, to that of the furnace, which we may assume is 1200°F. The furnace being at atmospheric pressure the vapor merely expands in volume as a gas. The specific heat of steam at atmospheric pressure is 0.464; that is, 1 pound of steam requires only 0.464 B.t.u. to raise it a degree, and 2.44 pounds of water will absorb

0.464 × 2.44 × 1200 = 1356.00 B.t.u.

Of this last amount of heat, approximately 50 per cent. is recovered as the gases pass through the furnace. The total loss of heat due to the evaporation of the water is

[195]

In the 100 pounds of coal under consideration, there is 100 pounds, less 2.44 pounds of water, or 97.56 of dry coal, each pound of which contains 13,732 B.t.u. as given by the table on page 193. This gives

97.56 × 12,682 = 1,339,753 = practically 1,340,000 B.t.u.

From this quantity is subtracted the loss of heat, 3439.

1,340,000 - 3439 = 1,336,561 B.t.u.

This represents the total available heat in 100 pounds of coal. If this quantity is now divided by the cost of 100 pounds of coal at $7.25 per ton, the result, 3,564,000 B.t.u., will be the available heat bought for $1 as given in column 7 of the table.

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[196]

CHAPTER X
ATMOSPHERIC HUMIDITY

The physical effect of atmospheric humidity has come to be recognized by all who deal in problems of house heating, sanitation and hygiene. The difference in effect of dry atmosphere, from that of air containing a desirable degree of moisture, is very noticeable in all buildings that are artificially heated. The effect of dry air is made apparent in the average home during the winter months by the shrinking of the woodwork and furniture. The absorption of the moisture from the building which is usually termed “drying out,” causes the joints in the floors and casements to open, doors to shrink until they fail to latch and drawers that have opened with difficulty during the summer then work freely.

Winter time is the season of prevalent colds, chaps and roughness of the skin, not so much on account of cold weather as because of dry air. The skin which is normally moist is kept dry by constant evaporation with the attending discomfort of an irritated surface and the results which follow.

The humidity of the air in which we live and on which we depend for life has much to do with the bodily comfort we derive in existence, and is suspected of being the cause of many physical ailments. Ventilation engineers not only recognize this condition but have found means of controlling it. It is possible to so control atmosphere temperature and humidity of buildings as to produce any desired condition.

Humidity of the Air.

—The amount of water vapor in the air is called the humidity of the air. It may vary from a fraction of a grain per cubic foot in extremely cold weather, to 20 grains per cubic foot during the occasional hot weather of summer.

Since the amounts of moisture that air will hold depends on its temperature, and as the air is ordinarily only partly saturated, the varying amount of moisture are expressed either as relative humidity and stated in per cent. saturation or in the actual weight of water in grains per cubic foot and known as absolute humidity.

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The relative humidity of the atmosphere is the amount of moisture contained in a given space as compared with the amount the same air could possibly hold at that temperature. Warm air will hold more moisture than the same air when cold. Air absorbs water like a sponge to a point of saturation. When the air is filled with moisture, any change which takes place to reduce the temperature also reduces its capacity to hold the water vapor and the excess is deposited as dew. This supersaturation ordinarily takes place near things which lose their heat faster than the surrounding air and the nearest colder surface acts as a condenser to receive the drops of dew. Grass being in convenient position is the commonest receptacle for dew formation. If the dew forms in the air it falls as rain, but if the temperature of the dew-point is below freezing, the dew immediately freezes and snow is the result.

In the consideration of problems that involve atmospheric moisture, both relative and absolute humidity are factors of common use, that are capable of exact determination. The relative humidity of the air is most readily determined and as it expresses the state of the atmosphere in which plants and animals live and thrive, as opposed to other conditions of humidity in which they sometimes sicken and die, it is one of the indicators of the quality of atmospheric air.

In the subject of ventilation, which is undertaken later, it will be found that a definite knowledge of atmospheric humidity has much to do with the successful operation of ventilation apparatus. Most people recognize the “balmy air of June” without realizing just why at the same temperature other seasons are not so delightful. In reality it is the condition of atmospheric humidity combined with an agreeable temperature that gives the kind of air in which we find the greatest degree of comfort.

The effect of moderately warm humid air is that of higher temperature than the thermometer indicates. When the atmosphere is near the point of saturation, the evaporation which usually goes on, from the surface of the body, practically ceases. In summer time a temperature of 85°F. with relative humidity of 90 per cent. saturation seems warmer than a temperature of 100° at 40 per cent. saturation, because of the cooling effect produced by the increased evaporation due to the drier air.

[198]

In winter, when most of the time is spent indoors, in an atmosphere that is very dry, the sensation of discomfort produced by the lack of humidity oftentimes leads to physical derangements that would never appear under more desirable conditions. The cause of many ailments of the nose, throat and lungs during the winter months is attributed by physiologists to breathing almost constantly the dry vitiated indoor air. The cause of dry air in buildings is not difficult to explain; it is a great deal more difficult to realize that the lack of water breeds so much discomfort.

In order to express the condition of humidity that may exist in the average dwelling, office or school-room during the winter, it is most convenient to refer to the results of varying atmospheric conditions that are given in Table 1—Properties of Air—which appears below. In the second column of the table, under the heading “Weight of vapor per cubic foot of saturated air,” will be found the amount of moisture in grains per cubic foot that will be required to humidify air at different temperatures. It will be seen that at 10° the air will contain, when fully saturated, only 1.11 grains of water, while at 70° temperature the same air would hold 8 grains of water. These amounts will be found in the column opposite the temperature readings. It is at once evident that when saturated air at 10° is raised to normal temperature 70°, the original amount of moisture is contained in an atmosphere capable of holding 8 grains of water. Its relative humidity will therefore be ^1.11⁄₈, practically 14 per cent. saturated. Unless moisture is received by the air from some other source this condition will produce a very dry atmosphere.

The normal atmospheric temperature of 70°F. with a relative humidity of 50 to 60 per cent. saturation produces a condition that is one of agreeable warmth to the average person in health and is recognized as the atmosphere most desirable. To some, this state of temperature and humidity is that of too much warmth and a temperature of 68°, with the same humidity, is most agreeable. At the same temperature, a reduction of the humidity to 20 per cent. saturation will produce a feeling of discomfort and the sensation will be that of a lack of heat. The cause for this latter feeling is due to excessive evaporation of moisture from the body.

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Table I.—Properties of Air

The evaporation of moisture is always accompanied with the loss of heat required to produce such change of condition. This is known as the heat of vaporization and represents a definite amount of heat that is used up whenever water is changed into vapor. No matter what its temperature may be—whether hot[200] or cold—when water is vaporized, a definite amount of heat is required to change the water into vapor.

Water may be evaporated at any temperature; even ice evaporates. A common instance of the latter is that of wet clothes which “freeze dry” in winter weather when hung on the clothes line. The rate at which evaporation takes place depends on the dryness of the surrounding air and the rapidity of its motion. In dry windy weather evaporation is most rapid.

As before stated, whenever water evaporates—at no matter what temperature—a definite quantity of heat is necessary to change the water into vapor. The exact amount of heat required to produce this change varies somewhat with the temperature and atmospheric pressure but it always represents a large loss of heat. At the boiling point of water (212°F.) the heat of vaporization is 970 B.t.u. for each pound of water evaporated, but at a lower temperature it is greater than that amount. At the temperature of the body (98.6°) the heat necessary to evaporate a pound of moisture from its surface is 1045 B.t.u.

It is the absorption of heat due to evaporation that cools the air of a sprinkled street. The more rapid the evaporation the more pronounced is the decline of temperature in the immediate vicinity. The same effect is produced when moisture is evaporated from the surface of the body. The acceleration of evaporation caused by a breeze or the blast of air from an electric fan is that which produces the chilling sensation to the body. During winter weather the effect of the cold wind is rendered more severe by evaporation of moisture from the body. In health, the body being in a slightly moist condition, the evaporation which goes on from its surface is what keeps it cool in warm weather, but if on account of excessive dryness of the surrounding air the evaporation is very rapid, a sensation of cold is the result.

Not only does excessively dry air produce the sensation of chilliness but the loss of heat from the body due to sudden or long exposure effects the general health and is conducive to chills that are followed by fever. In health the temperature of the body is constant and normally 98.6°F.; any condition that reduces that temperature tends toward a lowering of vitality and the consequent inability to withstand the attack of disease. In a very dry atmosphere the skin, instead of being slightly moist, is[201] kept dry, the result of which is the irritation that produces chaps and roughness of the surface.

Reports of the U. S. Weather Department show that the relative humidity of Death Valley, which is the driest and hottest known country, during the driest period of the year—between May and September—averages 15.5 per cent. saturation. In winter, many buildings, particularly offices and school buildings are not far from that atmospheric condition, constantly. Under the usual conditions of house heating, there is an almost absolute lack of means to give moisture to the air. Almost without exception steam-heating plants and hot-water heating plants in office buildings and dwellings are without any provision for changing the atmospheric humidity.

In school buildings that are not kept under a more desirable condition of temperature and humidity, the general health is impaired and the behavior of the pupils very markedly influenced. The tension of a school-room full of fidgety nervous children can be very promptly and greatly reduced by the introduction of water vapor into the air to 50 per cent. saturation.

All modern school buildings, auditoriums, etc., are provided—aside from the heating plants—with means of ventilating in which the entering air is washed and humidified to the desired degree, before being sent into the rooms.

The popular conception of the hot-air furnace method of heating is that it produces particularly dry air, when in reality it is the only type of house-heating plant in which any provision is made for adding water to the air. These furnaces are usually furnished with a water reservoir by use of which the humidity may be raised to a desirable point.

Much of the water which enters the air of the average home, during winter weather, comes from the evaporation that goes on in the kitchen. Usually on wash days the humidity is raised to a marked degree and that day is commonly followed by a short period of agreeable atmospheric condition. The arrangement of many houses is such that a much-improved condition of humidity might be obtained from the kitchen by continuous evaporation of water from a tea-kettle.

[202]

Relative Humidity
Depression of wet-bulb thermometer (t-t')

[203]

Relative Humidity (Continued)
Depression of wet-bulb thermometer (t-t´)

[204]

The prevailing impression seems to exist that when air is heated, it loses its moisture. In reality, air that is heated only attains a condition in which its capacity for containing moisture is increased. If after being heated to a high degree—and is relatively very dry—the air is reduced to its original temperature, the amount of moisture will be the same as was originally contained. In heating houses with hot air, the seemingly dry condition is usually due to temperature alone. When a hot-air furnace is provided with the customary reservoir for moistening the discharged air, it may be made to produce excellent conditions of atmospheric humidity. The heated air readily absorbs the water evaporated in the furnace from the water reservoir and enters the rooms as relatively dry air but containing more moisture than the outside air; when it has been reduced in temperature by mixing with the cooler air of the house, its moisture content remains unaltered and at the lower temperature its relative humidity is increased.

Relative Humidity.

—Suppose that on a damp day the outside temperature is 50° and that the atmosphere is 90 per cent. saturated. The air that comes into the house at this temperature and humidity is heated to 70°. The rise of temperature gives the air the property of absorbing additional moisture so that the relative humidity which was 90 per cent. is now much less. From the table relative humidity, will be seen that at 50° temperature and 90 per cent. saturation the air contains 3.67 grains of moisture. When the air is heated to 70°, it still contains the original amount of moisture but its relative humidity has decreased with the change of temperature. It is really the amount of moisture present—3.67 grains—divided by the amount necessary to saturate the air at 70°, which is 8 grains; this gives approximately a relative humidity 40 per cent. saturation.

As the temperature goes lower, less and less moisture is required to saturate the air. If saturated air at 0°F., which contains 0.48 grain of water, is raised to 70°F.—where 8 grains of water is required for saturation—the percentage of saturation would be ^0.48⁄₈ or 6 per cent.

The Hygrometer.

—The instrument most commonly employed for determining atmospheric humidity is the hygrometer. This appliance is composed of two thermometers mounted in a frame with a vessel for holding water. One of the thermometers[205] is intended to register the temperature of the air and is called the dry-bulb thermometer. The bulb of the other—the wet-bulb thermometer—is covered with a piece of cloth or other porous material which is kept saturated with water, absorbed from the water holder. The dryness of the air is indicated in the wet-bulb thermometer by the decline of temperature due to evaporation.

The rate of evaporation from the wet-bulb covering will vary with the humidity and if the air is very dry the wet-bulb thermometer will register a temperature several degrees below that of the other thermometer. If the air is saturated with moisture, no evaporation will take place and the thermometers will read alike. The relative humidity of the air as indicated by the readings of the thermometers is taken directly from a humidity table. The table is made to suit any condition of atmospheric humidity and the determinations require no calculation.

Fig. 157 shows the U. S. Weather Bureau pattern hygrometer such as is used at the weather stations. The wet-bulb thermometer has a muslin or knitted silk covering which dips into a metal water cup as shown in the figure. It is important that the covering of the wet bulb be kept in good condition. The evaporation of the water from the covering leaves in the meshes particles of solid matter that were held in solution in the water. The accumulation of the solids ultimately prevent the water from thoroughly wetting the wick.

An observation consists in reading the two thermometers and from the difference between the wet-bulb reading and that of the dry-bulb, the relative humidity is taken directly from the table. To illustrate, suppose that the dry-bulb thermometer reads 60° and that the wet-bulb reads 56°. The difference between the two readings is 4°. In the table of relative humidity on page 202, 60° is found in the column headed, Air temp. t, and opposite[206] that number in the column headed 4 is 78, which indicates that under the observed conditions the air is 78 per cent. saturated with moisture. This table is suited for air temperatures from 35°F. to 80°F. and depressions of the wet-bulb thermometer from 1°F. to 20°F. The table, therefore, has a range of variations which will admit humidity determinations for all ordinary conditions.

The Hygrodeik.

—In Fig. 158 is shown a form of hygrometer known as a hygrodeik, by means of which atmospheric humidity may be determined without the use of the tables. In the figure the wet-bulb and dry-bulb thermometers are easily recognized. A glass water bottle W is held to the base of the instrument by spring clips which permit its removal to be filled with water. Between the thermometers is a diagram chart from which the atmospheric humidity is taken. An index arm, carrying a movable pointer P, permits the instrument to be set for any observed thermometer readings.

The index is really a graphical method of expressing the figures given in the table on pages 202-203. In the picture the wet-bulb thermometer reads 65°, the dry-bulb thermometer 77°. To determine the relative humidity under these conditions the movable arm is swung to the left and the pointer P placed on the left-hand scale at the line 65°. The arm is then swung to the right until the pointer touches the downward curving line beginning at 77°, the dry-bulb reading. The lower end of the arm H now points to the relative humidity, where 52 per cent. is indicated by the scale at the bottom of the index.

The same result is obtained from the table of Relative Humidity. The readings of the thermometers in the figure give a difference in temperature of 12°, the dry-bulb thermometer[207] reads 77°. Referring this data to the humidity table, the column marked 12, for the depression of the wet-bulb thermometer and opposite 77° in the air temperature column, is found 53 which indicates the per cent. of saturation. The hygrodeik gives further the temperature of the dew-point, on the scale to the right; and the absolute humidity may be found by following the upward curving line nearest the pointer, at the end of which line is given the value in grains of moisture per cubic foot. The hygrodeik or other instrument of the kind is very largely used in places where relative humidity is regularly observed by those of limited experience, as in school-rooms, auditoriums, etc. Such records are not intended to be perfectly accurate and the readings of the hygrodeik are very well-suited for the purpose.

In using the hygrometer and the hygrodeik the instruments are stationary; they are usually hung on the wall in a convenient location for observation and are placed to avoid accidental drafts in order that the conditions surrounding the observation may be the same at all times. The evaporation which takes place from the wet bulb is due to natural convection and does not always reach the maximum amount. The evaporation is furthermore influenced by accidental variations and consequently the results cannot be considered exact.

Under conditions that demand more exact humidity records than are obtainable with hygrometer, the psychrometer furnishes means of making more accurate observation. The psychrometer shown in Fig. 159 is of the form used by the U. S. Weather Department. Like the hygrometer, it is composed of a wet-bulb and a dry-bulb thermometer but no water cup is attached to the instrument for moistening the wick of the wet bulb. When ready for use the wick is wet with water before each observation.

The greater accuracy to be attained by the use of this instrument[208] is on account of the maximum evaporation which is obtained from the wet bulb for any atmospheric condition. The evaporation which takes place from the wet-bulb thermometer in quiet air is not so great as that which occurs if the same air is in motion. In moving air, however, there is a certain maximum rate beyond which no further evaporation will take place.

The motion of the air may be produced either by blowing on the bulb with a fan or air blast, or by whirling the thermometer. With the psychrometer the latter method is used. This instrument is provided with a handle which is pivoted to the frame and about which it is swung to produce a maximum evaporation from the wick. When a motion of the air is attained sufficient to produce a saturated atmosphere about the bulb, the temperature will remain constant.

A velocity of air or the motion of the wet-bulb thermometer 10 feet per second is that usually taken as the rate for observation and the swinging is kept up 3 or 4 minutes or until the temperature of the wet-bulb thermometer remains stationary.

Then the temperature of each thermometer is read and the humidity found in the table. Relative humidity determinations may be made at temperatures below the freezing point if sufficient precaution is taken in the observations. When the instrument is not in use, it is kept in the metallic case shown in the picture, to protect it from injury.

Dial Hygrometers.

—Various forms of hygrometers are in use, in which a pointer is intended to indicate on a dial the percentage of atmospheric humidity. That shown in Fig. 160 is one of the common forms. Instruments of this kind depend for their action on the absorptive property of catgut or other materials that are sensitive to the moisture changes of the air.

These instruments give fairly accurate readings in a small range for a limited time, but they are apt to go out of adjustment from causes that cannot be controlled. Unless they are occasionally compared with a standard humidity determination, their[209] readings cannot be relied upon for definite amounts of atmospheric moisture.

The Swiss Cottage “Barometer.”

—Fig. 161 is one of the instruments of absorptive class that are sometimes used as weather indicators. The images which occupy the openings in the cottage are so arranged that with the approach of damp weather the man comes outside and at the same time the woman moves back into the house. In fair weather the reverse movement takes place. The figures are mounted on the opposite ends of a light stick which is fastened to an upright pillar. The movement of the images is caused by the change in length of a piece of catgut which is secured to the pillar and also to the frame of the house. Any change in atmospheric humidity causes a contraction or elongation of the catgut which moves the pillar and with it the images.

Since stormy weather is accompanied by a high degree of humidity and fair weather is attended with dry atmosphere, the movement of the images indicates in some degree the weather changes; but the device is not in any way influenced by atmospheric pressure and hence is not a barometer.

Dew-point.

—Dew is formed whenever falling temperature of the air passes the point where saturation occurs. The reduction of the temperature of air raises the relative humidity because of the diminished capacity to contain moisture. As the temperature declines there will come a point at which the air is saturated and any further decrease of temperature will cause supersaturation. At this point the moisture will be deposited on the cooler surfaces in the form of drops. The temperature at which dew begins to form is known as the dew-point. The sweating of cold water pipes, the dew that forms on a water glass and other relatively cold surfaces is caused by a temperature below the dew-point of the air.

[210]

Dew-point Table
Dew-point in degrees Fahrenheit, barometer pressure 29 inches

[212]

The temperature at which dew forms will depend on the amount of moisture present in the air, but with a definite humidity and air pressure it will always occur at the same temperature. If the dew-point is above freezing, the dew will form as drops of water, but if it is at or slightly below the freezing point, the dew will appear as frost. White frost is formed when the dew-point is only a few degrees below the freezing point. A Black frost occurs when the atmospheric humidity is so low that dew does not form until the temperature is much below the freezing point.

To Determine the Dew-point.

—The dew-point may be found by a number of methods, usually described in works on physics but practical determinations are made with a hygrometer or psychrometer and a dew-point table. Accurate determinations must be made by the use of the psychrometer; those made by the hygrometer are approximate. Suppose the reading of the dry-bulb thermometer is 68 and that this is designated as t; at the time the wet-bulb temperature is 57 and is called t´. The depression of the wet bulb for these temperatures (t-t´) is 11°. In the dew-point table above is found in the dry-bulb column, opposite this number in the column headed 11—under depression of the wet-bulb thermometer—is 49, which is the dew-point for the observed conditions.

As another illustration, suppose the dry bulb of the psychrometer marks 65° and the wet bulb indicates 56°F.; then 65-56 equals 9° of the cold produced by evaporation. The dew-point is determined in exactly the same way as with the hygrometer. Opposite 65, in the dry-bulb column of the dew-point table, under the column of differences marked 9, is found the dew-point for the observed conditions. This is 49° at which temperature dew will begin to form.

Frost Prediction.

—The formation of dew is always attended with a liberation of heat—the heat of vaporization—which tends to check the further decline of temperature. The heat thus developed is usually sufficient to prevent the fall of temperature beyond a very few degrees, but at times when there is little moisture in the air the fall of several degrees of temperature is necessary before the heat liberated by the forming dew balances the heat lost by radiation and the temperature remains stationary.

[213]

This condition of things was pointed out many years ago by Tyndall, who in his book on “Heat” states: “The removal for a single summer’s night of the aqueous vapor which covers England would be attended by the destruction of every plant which a freezing temperature would kill.”

The frosts of late spring and early fall which occur at times of dry air and cloudless sky are often caused by local conditions that are not forecasted by the weather department and often may be successfully combated.

At the time of suspected frost, the temperature of the dew-point in relation to the freezing point determines the probability of a freezing temperature. If the dew-point occurs at 10° or more above the freezing point there will be little danger of a killing frost. As the difference in temperature between the dew-point and the frost point decreases, the danger of frost increases. If the dew-point falls at the freezing point, frost is a certainty.

In using the table on page 214, the open diagonal line may be considered the danger line and any dew-point falling below the temperature thus indicated will be considered dangerously near the frost point. This table differs from the other dew-point table only in the range of temperature. The dew-point is found in exactly the same way as before. In the use of the psychrometer and table as a means of frost prediction it is first necessary to make a reading of the wet-bulb and dry-bulb temperature described above. The dry-bulb reading is found in the left-hand column of the table; then follow the horizontal line opposite the figure, till the perpendicular column is reached indicating the difference in reading between the dry and wet bulb. The number at the meeting will be the temperature of the dew-point. For example, suppose the dry bulb stands at 65° and the wet bulb at 55°, the difference being 10° and dew-point under these conditions will be 47°.

If the dew-point is 10° or more above the freezing point there is no danger of a frost, but if the conditions are such as to give a temperature difference less than 10° above the freezing point there would be danger. If the dew-point falls below the open diagonal line of the table there is danger and that danger increases as the difference in degrees between the freezing point and the dew-point becomes less.

[214]

As another illustration, suppose that at sunset at the time of suspected frost the dry-bulb thermometer read 54 and the depression of the wet bulb showed 10°. Referring to the table it will be seen that for these conditions the dew-point falls at 33 which is only 1° above the freezing point. It is highly probable that frost would form.

Dew-point Table for Frost Prediction
Depression of the wet-bulb thermometer

[215]

Prevention of Frost.

—From the discussion of frost formation it is evident that, the temperature of the dew-point being the determining factor in its probable occurrence, any expedient that may be used either to increase the humidity or to conserve the radiation of heat would prevent a dangerous decline of temperature. Frost prevention is practised in all fruit-growing regions and the method pursued depends on the kind of vegetation to be protected.

In the protection of orchards the use of smudge pots are probably the commonest means for preventing the loss of heat. The object is to create a cloud of smoke over and about the orchard so that it forms a protective covering which prevents the escape of the heat.

In the case of a light frost—that is, where the temperature falls only a few degrees below the frost point—the plants in small gardens and flower beds may be prevented from freezing by liberal sprinkling with water. This is done to raise the humidity of the atmosphere surrounding the vegetation. Most vegetation withstands the temperature at the freezing point without particular injury, and the freezing of part of the water liberates heat in sufficient quantity to prevent a further decline of temperature. This heat liberated on the freezing of water is described in physics as the heat of fusion and in changing part of the water into ice sufficient heat is liberated to check the further fall of temperature.

Humidifying Apparatus.

—Opportunity for adding moisture, in the desired quantity, to the air of the average dwelling is limited to the evaporation of water in the heating plant, from vessels attached to the radiators or that which goes on in the kitchen. Household humidifying plants are within the range of possibility but there is not yet sufficient demand for their use to make attractive their manufacture.

In the hot-air furnace a water reservoir is usually a part of the chamber in which the air supply is heated. The water in the reservoir is heated to a greater or lesser degree, depending on the temperature of the furnace and vaporized both by heat and by the constantly changing air.

In the use of a steam plant or hot-water heating plant the opportunity of humidifying the air is very limited. One method is that of suspending water tanks to the back of the radiators[216] from which water is vaporized. While this method is fairly efficient as a humidifier it is inconvenient and therefore apt to be neglected. In houses heated by stoves there are sometimes water urns attached to the top of the frame which are intended for the evaporation of water but as a rule they are not of sufficient size to be of appreciable value.

The quantity of water required to humidify the air of a house will depend first, on the temperature and humidity of the outside air; second, on the cubic contents of the building; third, on the rate of change of air in the building. If the ventilation is good the rate of atmospheric change is rapid and the amount of water in consequence must be correspondingly increased.

The data included in the following table showing the relative humidity and amount of water required were taken from a seven-room frame dwelling in Fargo, N. D., during particularly severe winter weather. The relative humidity determinations were made with a hygrodeik each day at noon. The house was heated by a hot-air furnace arranged to take its air supply from the outside.

The air supply is recorded under Cold-air intake. The furnace was provided with a water pan for humidifying the air supply. The amount of water evaporated each day is recorded in the column headed Evap. in 24 hours. The outside temperature ranged from -12°F. to -21°F. The weather was clear and calm except the last day, Jan. 12, which was windy. The higher humidity on that day was no doubt due to the greater amount of heat required from the furnace and the consequent evaporation of the water from the water pan.

The humidity determinations made by a hygrodeik, as before explained, are only approximately correct but sufficiently exact for practical purposes. The temperature is given in degrees Fahrenheit.

In the table it will be noticed that the outside air was used only a part of the time because of the severity of the weather. Attention is called to the quantity of water required to keep the humidity at the amount shown. This averages 27½ quarts per day. At the time these observations were made the physics lecture-room at the North Dakota Agricultural College averaged 18 to 20 per cent. saturation during class hours, with observations[217] made from a similar instrument. This is a steam-heated room with only accidental means of adding water to the air. The result was an atmosphere 3½ per cent. above that of Death Valley.

Hot-air Furnace
Readings taken at 12 o’clock noon each day

The amounts of water evaporated may seem large to those who are unaccustomed to quantitatively consider problems in ventilation but the small amount of water in the air at -21° must produce a very dry atmosphere when it is raised to 70° in temperature.

The amount of moisture in air at 20°F. and at 80 per cent. humidity is only 1.58 grains to the cubic foot. If this air is now raised to 70° the moisture will still be 1.58 grains where there should be 4 grains of water to make 50 per cent. humidity. It therefore will require the addition of practically 2.42 grains of water for each cubic foot of entering air in order to bring it up to 50 per cent. humidity.

In a case with the above conditions of atmosphere, suppose it is desired to know the amount of water that would be taken up in humidifying the air for a school-room of size to accommodate 40 pupils. The prescribed quantity of air for this purpose is[218] 30 cubic feet per minute for each pupil. The air is to be maintained at a humidity 50 per cent. saturated. The problem will be one of simple arithmetic. If each pupil is to receive 30 cubic feet of air per minute or 1800 cubic feet per hour, the 40 pupils receiving 1800 cubic feet per hour will require 40 × 1800 = 72,000 cubic feet of air per hour. To each cubic foot of the air is to be added 2.74 grains of water, 72,000 × 2.42 = 164,240 grains of water. Reducing this to pounds, 164,240 ÷ 7000 = 23.46 pounds or 2.77 gallons of water per hour.

In practice the room will show a higher amount than 50 per cent. humidity with this addition of the amount of water, because of the water vapor that is exhaled from the lungs of the pupils. That a considerable amount of water vapor is added to the atmosphere by breath exhalation is made evident from the moisture condensed by breathing on a cold pane of glass. In any unventilated room occupied by a considerable number of people the humidity is thus increased a very noticeable amount.

The change in humidity of the air in a closed room filled with people is very pronounced. The constant exhalation of moisture from the lungs is sufficient to saturate the air in a short time. The heavy atmosphere of overcrowded, unventilated rooms is due to moisture exhalation, body odors and increased carbonic acid gas. As the humidity of the atmosphere is increased a sensation of uncomfortable warmth is the result of the lesser evaporation.

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