Mechanical Devices in the Home

CHAPTER III

Oil Stoves

22. Purpose of Oil Stoves. Oil stoves are designed for the comfort of the woman who cannot have a gas or an electric stove. They consist of tank, feed pipe and burners (Figs. 11-a and 11-b). As they are portable, they can be moved to a summer kitchen or sheltered back porch on hot summer days.

Oil stoves are not fool-proof and should never be used by those who are afraid of them and who do not understand them. Manufacturers have done much to make accidents avoidable, and they send detailed instructions with each stove. These should be followed exactly.

23. Mechanical Parts of Kerosene Stove. The kerosene oil stove consists of a tank of oil with a pipe leading to a hollow ring-like cup below the burner (A, Fig. 11). When the burner is lighted, the oil passes down this pipe into the ring, where it becomes heated and is vaporized. As the vapor rises, it is mixed with air and burns with a blue flame. The small holes in the chimney of the burner and at the base of the burner are to admit air. They must be kept open.

If the burner is dirty or not properly adjusted, the right amount of air may not reach the vaporized oil to mix with it and the stove will burn with a yellow flame, making soot and smoke.

24. The Burner. The burner consists of a chimney, a wick or ring of asbestos, a valve or a lever, and a ring-like cup at the base of the burner. There are three distinct types of burners known as long chimney, short chimney and wickless. The wickless stoves are equipped with a ring of asbestos which serves the purpose of a wick.

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The burners on one oil stove are usually all alike. The burners on various makes differ. Those in which the flame comes nearest the kettle or cooking food produce the most heat for cooking (Fig. 12). Those with the blaze farther away from the food seem to be easier for the excitable woman to manage (Fig. 13).

25. The Chimney. Kerosene stoves are furnished with metal chimneys. A device for mixing air with the burning fuel forms a part of short chimneys (B, Fig. 11). The chimney must set on the burner properly, or the stove will not burn with a blue flame. After lighting a burner, give the chimney a turn or two to make sure that it is in place. There is usually a groove into which it fits.

26. Lighting the Stove. When lighting a stove, turn the valve which permits the oil to flow (C, Fig. 11) into the cup below the burner, or lower the lighter into the oil. Wait a moment, if need be, for the wick or ring to become saturated with oil. Raise the chimney and touch the lighted match to the ring or wick at several places. (Fig. 14, and Fig. 11, also, show the position of the chimney and wick for lighting.) Lower the chimney, seeing that it fits back into place. Adjust the wick to the proper height to get a blue flame (Fig. 15). Do not turn very high at first, for, while the stove is becoming heated, the flame burns higher and higher, and may begin to smoke.

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27. Management of the Flame. Turn the flame no higher than is needed to keep the pot boiling. Some stoves do not burn well when turned very low. Do not have the flame so high or so low that it gives off smoke or gas. When turning out the fire, be sure to turn the wick clear down, or turn the valve or lever (Fig. 12) to the point indicated as out on stoves which lift the ring above the oil. If this precaution is not taken, most stoves leak oil when not in use, because the wick or rings carry oil to the upper part of the burner where it spreads over the stove.

28. Adjustment and Care of the Stove. To prevent trouble with uneven flames, set the stove perfectly level, particularly the wickless one. Keep the tank filled, but not too full. Stoves are made so that it is difficult to fill them too full. An oil stove cannot explode unless gas has formed in some part, like the tank, and becomes ignited by heat or a spark. Gas is more likely to collect in the tank when it is almost empty.

When the tank is removed for filling, any gas forming passes out into the room and mixes with so much air that it is harmless. If it is filled before the oil burns out of the pipe above the level of the burners, no gas will be formed.

Stoves must be kept clean. A clean stove means one with a clean framework, clean burners, clean chimney, clean oil and a clean wick or ring.

If a stove has not been in use for some time, replace the old wick with a fresh one (Fig. 16). Clean the stove by wiping off all the parts with a cloth. Keep the charred edges of the wick trimmed level. The wick with a crust of char on top does not burn well. Use a match or small stick in removing the char. Light the wick to see if it is even. If any point burns with a yellow flame, trim this place until the wick burns even. The tank can easily and quickly be lifted off modern oil stoves. Do not refill near a lighted stove.

29. When the Stove Gives Trouble. In case the stove begins to blaze and cannot be controlled by the valves, remove the tank and carry it to some safe place where the kerosene in it cannot catch fire. When this is done, there is less than a pint of oil left in most stoves, and this will soon burn out without doing much harm, if clothing and water are kept away from the blaze. Open windows and doors to let out gases and smoke. If necessary, move the stove away from walls or furniture. Do not attempt to smother out the flame. There is too much danger of clothing catching fire when this is done. It is far safer to let the small amount of oil left in the stove burn up. Oil stoves cannot explode when the tank is removed.

As soon as the oil has burnt out of the pipes and the wicks are burning with a dull glow, extinguish the smoldering fire on the wicks by patting them with the blade of a knife or a piece of woolen cloth.

If a burner has been blazing beyond control, remove the chimney. Brush out any soot which has formed. Examine the burner, taking it apart, if possible. Blazing may come from wicks not fitting, or from their getting so short that the screw on the lever fails to move them up or down. The ring in wickless stoves may not be thick enough, or they may have slipped out of place, or become broken. Replace with new wicks or rings.

Notice if any part of the burner shows evidence of melting. If it does, do not use this burner until inspected and mended by an expert. If the lever has become worn so that it fails to work, it must be replaced or a new burner put on the stove.

30. Construction of Gasoline Stoves. The gasoline stoves consist of a burner and an oil tank connected by a pipe (Fig. 17). The tank is elevated for the purpose of forcing the gasoline into the burner. The pipe may be any length. The danger from a gasoline stove comes from the fact that gasoline vaporizes at a low temperature. If the tank becomes heated, producing gas, and then becomes mixed with the proper proportion of air, it may explode if it comes in contact with a spark. (Fig. 17-a is an illustration of the cross-section of the Red Star gasoline or vapor stove. See page 38.)

From the pipe to the burner is a very small opening, so that a stream of gasoline little larger than the diameter of a needle flows into the burner proper, when the valve is open. The valve may be partly closed so that the stream will not flow so fast.

Below the burner is a small cup. When the stove is cold, the gasoline flowing into the burner collects here.

31. To Light the Stove. The way to light the stove is to turn on the gasoline until it fills the cup below the burner. When this is full, close the valve. Set this gasoline on fire. As it burns, it will heat the burner.

The burner is heated so that when more gasoline is turned on, this heat will change the gasoline to gas. If the burner is not hot enough to do this, the gasoline flowing from the pipe will flow down into the cup and the stove will burn with a smoky flame which becomes higher and higher and looks very alarming.

When this happens, the valve should be closed, and the fire permitted to burn all the gasoline which has collected in the cup. This may be sufficient to heat the burner. Test after the fire has gone out, by lighting a match, turning on the gasoline and touching the lighted match to the burner. If all right, it will burn with a blue flame; if not, it will burn with a yellow flame. If the yellow flame is noticed, turn out the fire by closing the valve, and let the burner get cold before attempting again to light it. See that the burner has not become clogged with soot or dirt. Then proceed to re-light the stove.

Air must be mixed with the gasoline to make it burn with a blue flame. The air enters the burner through the same tube that the gasoline flows into the cups when the burner is cold. In the burner are small holes for the escape of the gas mixed with air, and here the blue flame should appear, and nowhere else. If it appears elsewhere, the burner is not working properly. Sometimes the gas ignites at the point where the air is mixed with it. The fire should then be turned out and the stove re-lighted immediately.

If the little holes where the flames should be, or if any other part of the stove is clogged with soot, it will not burn as it should. It must be cleaned. A dirty gasoline stove is dangerous.

32. Filling the Gasoline Stove. Never get oil on the tank or any part of the stove while filling it. If oil is spilled, wipe it up before igniting the stove. Do not fill the tank when the stove is lighted or when there is a fire anywhere near the tank. If the fire has been burning, close all the valves and wait until it goes out before opening the tank. Close the valve from tank to pipe before filling. Fill the tank and cover it before lighting the stove again.

Keep the tank filled. As soon as the indicator, which is attached to a cork which floats on top of the gasoline, shows that the oil is low, turn out the fire and refill the tank. Do not fill the tank to overflowing. Gases from the stove can only get into the tank when it is empty and while there is gasoline in the pipe to feed the stove. Gasoline gas is very inflammable and will cause an explosion if it becomes ignited. The tanks from gasoline stoves cannot be removed, as all the joints must be tight to prevent the escape of gasoline fumes as well as the oil itself. The opening to the tank must never be left uncovered, except for the few minutes while the tank is being filled. The greatest care is required in using a gasoline stove; in fact, they are so dangerous, that they should not be highly recommended for household use. The description and care of them are given here because some persons persist in using them when they desire a quick, hot fire in cases where fuel gas is not available.

33. When a Burner Blazes and Cannot Be Controlled. When a gasoline stove burner blazes and cannot be controlled, first close the valve leading from the tank into the pipe. There will then be little gasoline to burn, and no gases can get back into the tank.

Keep clothing and water away from the blaze. Remember that the stove is set on a metal frame which is not inflammable. Shield walls and other objects so that the burner may blaze high without doing damage. Clothing catches fire easily, but the metal stove will not be consumed.

If the valves are shut, the blaze will cease when the gasoline has burnt out of the burner and pipe. If the gasoline continues to flow out of the burner in spite of turning the valve and there is a danger of its spreading to the floor or table, set a shallow pan under the stove to catch the gasoline. It can burn in this way with considerable safety. Do not attempt to carry a burning stove. Simply protect floor, walls and furniture from catching fire, and let the gasoline burn.

34. Changing Fuel in Vapor Stoves. There are some stoves which are interchangeable, in that they may be adjusted to burn kerosene, gasoline or distillate. These are of the type called "vapor" because they change the oil to gas before it is ignited. A change from one kind of fuel to another should never be made without thoroly cleaning the stove and adjusting it to the fuel that is to be used.

35. Operation of Vapor Stoves. It is safest to use kerosene in these stoves. Distillate is a name given to a different mineral oil product from kerosene or gasoline. To work well, these burners must be kept clean. (Fig. 17-a.)

The operation of the stove is simple. Put enough fuel, such as alcohol, into a burner to heat it hot enough to change the oil to be used to gas and ignite it.

After the burner has heated for three or four minutes, turn on the fuel valve in the pipe which leads from the tank to the burner. The fuel will light from the burning alcohol already in the burner. Adjust the height of the flame by valve, which regulates the amount of fuel flowing into the burner.

If anything boils over, put out the fire. Close the valve. Remove the parts of the burner. Clean and wipe them dry. Replace the parts of the burner, and, if not cool, turn on the fuel and light. If cool, heat as for first lighting, and turn on the fuel.

Extinguish the fire by closing the valve which stops the flow of oil to the burner.

CHAPTER IV

Electric Stoves

Electric stoves consist of frame, heating unit and switches to regulate the flow of current. Some are equipped with oven, thermometers and special utensils (Fig. 18).

36. Heating Unit of Electric Stove. The heating unit consists of coils of wire or a plate of metal thru which the current flows, meeting resistance and producing heat. If the current flowed freely thru the wires, little heat would be generated (Figs. 19 and 20).

37. Wiring of Stoves. It is advocated that a separate circuit of heavy wire be put into all houses where current is used for purposes other than lighting, to provide for cooking and power connections.

Too heavy loading of wires with electric appliances causes the burning of fuses and sometimes damages the electric system. Find out how much current the wiring of the house will carry before attaching new devices. There is danger of fire if too much current is allowed to pass over a wire of too small size.

38. Operation of Electric Stoves. Many stoves are equipped with a switch which permits different amounts of current to pass thru the stove according to the way the device is set. At one point it gives low heat; another, medium, and a third, high heat, and, lastly, no heat.

The cooking of food on an open burner should be started with high heat turned on so that the food may cook quickly. If a large amount of food is cooking, there will be so much radiation from the vessel that it may require all the current to keep it cooking. After food has started cooking, the switch can be turned to medium, and, later, to low, depending upon the amount of food and the temperature desired. Low will keep an ordinary pan of water boiling, once it has started.

A few minutes before the food is to be removed from the open burner, the current should be turned off, as the heat in the stove will continue the cooking for several minutes. From tests of electric stoves, it appears that in most of them the food will continue to cook after the switch is turned off for about the same number of minutes that it requires to raise the heating unit to a temperature sufficient to boil water in a small shallow pan. A housekeeper who is using electricity for cooking can soon learn how long the open burners and oven of her stove will keep food cooking after the current is turned off, and by putting this information to use, she can save many dollars in a year.

39. Care of Electric Stoves. When thru with a stove, always turn off the current. Great care should be taken that the stoves do not become overheated. This shortens the life of the stove.

Sudden cooling of the coils of wire caused by liquids spilling on them, and corrosion of the wires caused by dampness, wear out stoves faster than need be. Do not wash or brush dirt from burners having open coils of wire. Burn all dirt from the burners.

40. Utensils for Electric Stoves. The most economical use of electricity can be secured with utensils built around the heating units (Figs. 20 and 21), and the next most economical use with utensils built especially to fit the heating units. This means that there would be a heating unit for each utensil, or size of utensil, and the expense of equipment would be considerable. Also, more care would be needed in washing the utensils and in preventing them from becoming bent. Such facts must be considered in choosing between stoves with special devices and those on which any pan may be set. After installing an electric stove, start with new utensils because they will not blacken on an electric stove, and so can be washed with the other dishes.

When ordinary household utensils are used, they should be of such shape that they stand flat, as they also should on a coal range. The most economical use of heat is secured when the area of heat is smaller than the area of the bottom of the kettle and is concentrated on the utensil. Care should be taken when stoves are installed, that they are properly grounded so that they cannot burn any one. A light bulb is attached to some stoves so that when the current is on the light burns, and when it is off, the light goes out. Such a light should be on all large stoves.

41. Detachable Cooking Devices. Cooking and heating devices should have larger wires than those for lighting alone. Consequently, the attachment of a heating device in a common light socket may cause burning out of fuses or other damage.

One danger in using detachable electric devices occurs in not turning off the current when the stove is not in use, thus permitting it to become overheated. This shortens the life of the stove.

Any tendency of a stove or other electric device to give people a shock when being used should be taken as a warning to have the device examined by an expert and the trouble corrected. Have the wires repaired as soon as the insulation breaks or burns off. Uninsulated wires, such as cables and cords, are unsafe.

CHAPTER V

Alcohol, Acetylene, and Canned Heat

42. Alcohol Stoves. Alcohol stoves are made only in small sizes for light housekeeping. There are three general types of these—those which burn with a wick, those which generate gas, and those which permit the alcohol to burn off of the top surface of the container.

Alcohol does not produce much smoke in burning, even when no provision is made for mixing air with it. The ordinary alcohol lamp, having a wick, may be used as a heating stove. Stoves with wicks draw the alcohol up by capillary attraction to the point of ignition, and the metal jacket about the wick prevents the fire burning back into the bowl containing the alcohol. The char from the top of the wick must be brushed off from time to time. No other care is needed for these stoves or lamps. Some of them are provided with devices for checking the burning of the alcohol in order to regulate the heat. This is desirable since a small flame of alcohol produces much heat.

Extinguish the fire by covering the wick with a metal cup.

43. Vapor Stoves. Alcohol vapor stoves which generate gas hold the alcohol in a tank slightly raised above the level of the burner. A pipe leads from this to the burner, where a small stream of alcohol is permitted to enter when the valve is open.

When starting these stoves, the valve is first opened and enough alcohol allowed to flow out to fill a cup which is below the burner. This generally holds about a tablespoonful of alcohol. When the cup is full, the valve is closed and the alcohol in the cup ignited.

This heats the burner enough to vaporize the alcohol. When the burner is heated, open the valve and ignite the gas. If all the alcohol is not vaporized, the burner has not been heated hot enough. Close the valve until all the alcohol in the cup is burnt.

44. Wickless Stoves. Wickless alcohol stoves are used commonly on chafing dishes. The burner of one type consists of a metal dish packed with a porous material which is non-inflammable, but a good conductor of liquids by capillary attraction, and the top is covered over by a wire screen. The alcohol is poured into the dish. The packing and screen prevent air from entering the bowl with sufficient rapidity to let the fire burn below the screen so the flame stays above it, burning off any alcohol which is conducted to the surface.

The only possible way to control these stoves is by a device which can cut off air. One of these is a plate-like device with a handle. This fits over the stove and only that portion of the top burns which is exposed to air through the hole in the plate. Making the hole larger or smaller makes the burning surface larger or smaller.

To extinguish the fire, cover the entire top with a solid plate to cut off all air.

45. Canned Heat. Canned heat is alcohol combined with other substances into a cake about the consistency of hard soap. The cover to the can is used to extinguish the fire. It should not be fitted into the top of the can until the flame has been extinguished for two or three seconds. Then it should be fitted on as tight as possible to prevent waste alcohol by vaporization.

46. Acetylene Gas Stoves. By adjustment of the amount of air that enters the burner, acetylene may be burnt in a gas stove. Usually a cap is placed over the air hole while the gas is being ignited. This is removed as soon as the gas is lighted, so that it will burn with a blue flame. The use of the cap prevents burning back. It is best, however, to use stoves especially designed for burning acetylene.

CHAPTER VI

Fireless and Steam Cookers

47. The Fireless Cooker. The fireless cooker is a box or can having a diameter somewhat larger than that of the largest vessel to be placed in it. The space left around the vessel is packed with some insulating material to keep in the heat (Fig. 22). In home-made cookers, this material may be hay, feathers, pillows, shredded newspapers, wood shavings or sawdust. In commercially-made cookers, it is felt, asbestos wool, cork, or other insulating material. Because most insulating material will not stay in place and readily absorbs moisture and odors, some kind of lining is put between it and the vessel holding the food. This makes a little nest, into which the vessel fits. In the better made cookers, this lining is made of metal, and the seams are water-tight.

The steam from the cooking food is absorbed by the insulating material if this lining is not impervious to water. Enameled or earthen linings, if well glazed, would also serve this purpose as long as they did not chip or crack.

The cover, as well as the sides, of the fireless cooker has to be padded with the insulating material. The cover must also fit well so that the steam and heat will not escape thru cracks between it and the body of the cooker.

48. The Stones of Fireless Cookers. The stones for fireless cookers are usually made of soapstone or some composite which will absorb considerable heat. They should be slightly smaller in diameter than the nest. They can only be used with safety in cookers which are metal-lined and insulated with material which will not ignite at a low temperature. Stones should not be put in home-made cookers which are not insulated with asbestos or other fireproof material. Hot stones can be used with safety in any of the commercial cookers which come fitted with them.

The temperature in a fireless cooker is below boiling most of the time. It is, therefore, a device for simmering food, and should be used for cooking meats, fruits, vegetables and cereal dishes which require or are improved by long, slow cooking.

Since the food has to be shut in a fireless cooker to keep in the heat, fireless cookery is a method of steaming of food. For this reason, it has a slightly different flavor from food baked in the oven, much as fried food differs from roasted food. Hot stones (Fig. 22) are put in most fireless cookers. The heat from these brown the food and give to the otherwise steamed food a flavor similar to that developed in baking, roasting and frying.

49. Heating the Stones. Moisture given off by the cooking food is absorbed by the stones. They must be dried or heated very slowly to prevent this moisture from cracking them. When the stones have been removed from the cooker, wash them, because they absorb odors from the food. Keep them in some warm, dry place while they are not in use, such as in the warming oven of the cook stove or on a radiator. When wanted for use, they will then be dry enough to be placed over the gas-stove burner if it is not turned too high at first. Drying thus saves time when the stones are needed.

50. Care of the Cooker. The cooker should be left open to air while not in use. As soon as the food and stones are removed from it, the moisture should be wiped out and the inside washed with soap and water, wiped dry and left to air. Such care is needed to prevent the cooker from taking on the odor of dishes previously cooked and transmitting some of them to those cooked later.

51. Other Devices Belonging to Cookers. In most commercial cookers there are wire devices to raise the dishes of food from the stone (Fig. 23). This prevents scorching and boiling over when the stones are heated very hot. These devices are also used to hold a hot stone above the food to make a brown crust on it. Some cookers are furnished with valves, permitting the escape of steam when it becomes too abundant. The pressure of the steam automatically opens the valve. This device insures the cooking of certain vegetables, cereals or doughs without their becoming too soggy to be palatable (A, Fig. 23).

52. Directions for Using the Cooker. Put the stones on to heat. Prepare the food as for cooking in any other way. Then heat it, either in the oven or on top of the stove. It is preferable to heat the food in the same vessel in which it is to be cooked in the fireless cooker. Transferring food to a cold vessel entails a loss of heat, since the first vessel is already heated.

When the stones and food are hot, place the stone in the bottom of the cooker. Put in any asbestos mats or other devices which are needed to protect the food. The stone should be hot enough to respond to the test for flat irons. It should make the snappy noise of a good hot iron when the finger is moistened and touched to it. Place the food in the cooker. Place another stone above the utensil if it is desirable to have the food brown on top. Close the fireless cooker, and let it stand until ready for use.

53. Time of Cooking Food. Six hours or over night should be allowed for the cooking of cereals. Stews should be given two to three hours' time for cooking.

Large roasts and hams require five to six hours. It is sometimes necessary, when they are large, to remove them and heat the food and the stones on the stove once during the process of cooking. Dumplings and angel cakes cook well in a fireless cooker. So do all dried peas and beans.

It is profitable to cook foods requiring more than forty minutes' heating in a fireless cooker. The heating unit is a part of some cookers.

Electric cookers, instead of being furnished with stones to be put inside the nest, have a heating unit and plate for holding heat in the cooker. Cold food may be put into this cooker, the current turned on, and the heating and cooking all be done inside the cooker. The electric oven which is well insulated answers the purpose of a fireless cooker when the current is disconnected. Either a thermometer, which the housewife may watch, or thermostat, which controls the current, must be attached to electric cookers to prevent burning the food or injuring the cooker with too much heat.

54. Gas Cookers. Since heated air rises, special cookers in the form of insulated caps are made to put over dishes of food heated on gas burners (Fig. 24).

The inside of the cap must be kept clean. Get the dishes hot with the cap suspended over the food, but leaving about an inch space for the escape of gases from the heating unit. As soon as the food and cap have been sufficiently heated over the fire, turn off the gas and lower the cap so that it will retain the heat. After the cooker has been used, it should be wiped out clean; otherwise it will retain some of the odors of the cooked food.

55. Steam Cookers. There are several steam cookers in use in homes. The simplest of these is a covered pan which has a perforated bottom, which is set over another pan (A, Fig. 25), in which water is placed for forming steam. One of the difficulties of this cooker is that the water in the lower pan cannot be watched and may boil dry. On the more improved cookers a whistling device (B, Fig. 25) is attached to the pan, and when the water becomes low and steam ceases to flow through it, air begins to come in, and the device makes a whistling noise.

Questions for Part I

PART II

Heating Devices

CHAPTER VII

Warm-Air Furnaces

56. Principle Upon Which a Furnace Works. The success of warm-air heating depends on a natural circulation of air thruout all the rooms which are to be heated. The air is the vehicle of transmission of the heat from the fire to the rooms to be warmed.

A warm-air furnace is simply a large stove encased in a sheet-metal jacket (Figs. 26 and 27). The jacket is usually insulated with asbestos, since the stove is set in the basement where radiation of heat is not desired. The air entering the casing is warmed by the stove. As the air is warmed, it expands and becomes lighter, so rises to the top of the furnace; from here it is conducted to the rooms above. The warm air which has passed upward must be replaced by cooler air entering at the bottom of the jacket. In the rooms above, there must be outlets for the cold air, already in them, so that it may be replaced by the incoming warm air. Cold-air shafts from the floor leading downward serve as outlets. Sometimes they return the cooled air to the base of the furnace jacket.

57. The Stove Part. The stove part of the hot-air furnace consists of a fire pot supported above a place where the ashes may fall and a chimney to carry off smoke. The draft below the grate in the fire pot lets in air which is essential to the proper burning of the fuel. In this respect, it is similar to a cook stove. A draft above the fire when opened a little lets in air which aids in the complete combustion of the gases given off by the fuel. Burning these gases adds to the amount of heat secured from the fuel. Opening the draft wider checks the burning of the fire. There should be a damper in the smoke pipe. When this is closed, it checks the draft up the chimney. This is needed because some chimneys often draw up air too fast to make the fire burn well. When checking the fire, close the draft below, open the one above the fire box, and close the one in the pipe. To make the fire burn fast, open the draft below, close the one above the fire box, and open the one in the pipe. Remember that a fire will not burn well if there is too much draft. Adjust the drafts until the fire burns with a clear, bright flame without giving off smoke. After a fire is built, the manner of adding fuel makes a difference in the efficiency of the furnace. When using coal, add it in rather small amounts, spreading it in a layer over the entire fire. Do not make this layer so thick that the fire smokes. The fuel will not burn with a clear flame if the fire is being smothered. Much fuel is wasted by ignorant and careless management of furnaces.

58. The Cold-Air Shaft. It is through a cold-air shaft that the cooler air comes into the furnace. Some furnaces have this built so that it draws the cooling air from the rooms above down into the furnace to be heated again. This is an economical arrangement. Some others draw fresh air from out of doors into the furnace, letting the cold air from the rooms above drain into the cellar and out of doors. This is more expensive, as the air to be heated is usually colder, but it has the advantage of helping ventilate the rooms by bringing a constant supply of fresh air.

The cold-air shaft leading from out of doors should have the outer end covered with wire mesh, and a cloth which should be washed or renewed often.

Never sweep dirt down a register or cold-air shaft. It comes back into the room in time. Dust the registers occasionally.

In older heating systems, there was but one large cold-air shaft to drain the cold air from the rooms above. In more modern houses, a cold-air shaft is placed in every room that may be shut off from the others. This does away with the old difficulty of heating a closed room, for it is as important that the colder air gets out as that the warm air gets in.

59. Hot-Air Pipes. The hot-air pipes lead from the top of the jacket about the furnace to the floor above. In most houses, one pipe goes to each room. This is unnecessary if the rooms are not closed off, but if they are, they need the pipe entering the room. To economize with heat and regulate the amount of air passing up these pipes, there must be a shutter in them, near the furnace, as well as in the register. This shutter is placed near the furnace so that no heat passes into the pipe when not wanted in the room to which it leads. This saves waste in radiation from the pipe in the cellar. When a room is not in use, close this damper.

Since warmed air will continue to travel upward so long as it stays warmer than the air above, it is important that the pipes have a continuous rise thruout their entire length, the in some parts the rise may have to be only very slight. The shorter the pipes, the better, for there will be less loss of heat from radiation on the way to the rooms.

60. Location of the Furnace. A central location for the furnace is best because the pipes may be shorter, and this makes possible a greater elevation per foot of each pipe, so that the air can flow thru it faster. A central location also permits a uniform distribution of pipes about the furnace, which, in turn, produces a more even flow of air to all the rooms.

The air from the hot register rises to the top of the room, or, if the way is open, to the top of the house. Here it spreads over the upper area. As it cools or is displaced by still hotter air, it falls. When it reaches the floor, it flows down the cold-air shaft in the floor. If the cold-air shaft is not in the floor, there may be a layer of colder air there so the room will not be comfortable.

61. Air. There is a constant change of air in all houses, due to opening of doors and the fact that walls are not air-tight. This may not be enough for comfort. If a room is not heating well, it has been found that opening the window to change the air in the room, even when the outside air is very cold, helps in the circulation of air in the room, and so with the warming of it. It is difficult to warm a room filled with stagnant air.

62. Pipeless Furnaces. The pipeless furnace works on the same principle as the one with pipes (Fig. 28). One large opening above the furnace lets the heat in to some central room, and from here it circulates into all other rooms not closed off from the central room. The cold-air shaft may be around the opening for heated air.

Stoves encased in a metal jacket that operate like hot-air furnaces (Fig. 29) are used in heating one-room schoolhouses and other small public buildings.

CHAPTER VIII

Hot-Water System of Heating

63. Equipment for Hot-Water Heat. The hot-water system of heating a house consists of a boiler in the basement or below the level of the lowest radiator. This boiler is designed to heat water as it circulates through coils over the fire (Fig. 30). From the boiler, pipes lead to radiators and an expansion tank, and return pipes bring the cold water back to the bottom of the boiler (Fig. 31).

The heat from the furnace fire causes the water to circulate through this system of boiler, pipes, radiators and tank, due to the fact that hot water is lighter than cold water.

64. Heating Unit. The heating unit of a hot-water system is like any stove consisting of a fire pot and grate. Some are adjustable so that different kinds of fuel may be used. A gas burner is sometimes placed in the fire pot and used for heating a furnace, but this is one of the most wasteful ways of using gas. A real gas furnace is much more economical. The fire and heat from the fire circulate around the coils containing the water. If the coils are not constantly kept full of water, they will be injured by the heat.

65. The Management of the Fire. When burning coal, spread the coal all over the surface of the fire in a thin layer so as not to smother it and thus make it burn with a smoky flame. Keep the ashes cleaned out from underneath the fire and around the fire pot. Clean the flues every forty-eight hours. Soot on the coils is more effective than asbestos would be in keeping heat from penetrating to the water. Regulate the fire with the drafts. Open the one below the fire box to let in air to aid combustion. Open the one found in most furnace doors a very little. This aids in the combustion of gases, thus making more economical use of the fuel, while opening it wider checks the burning of the fire. Broken and warped doors and drafts let in too much air and destroy the efficiency of the heater. Open the chimney damper, shown in Fig. 2, Sec. 3, admitting air to check the draft. Close the chimney or pipe damper of the type of cook stove shown in Fig. 2, Sec. 3, to check the draft up the chimney.

66. The Pipes. The pipe carrying the hot water from the boiler out to the heating system leads to the expansion tank, the sometimes separate pipes lead from the boiler to a radiator. Insulate each pipe, except the part in the room to be heated, with asbestos or some other covering, to keep the heat in it. Keep the pipes full of water. When they are installed, see that they are put in so that they gradually rise upward. If they dip downward at any point, air will collect at these places and check the circulation of hot water thru pipes.

67. Expansion Tank. The expansion tank (A, Fig. 31, and Fig. 32), placed somewhat higher than the top of the highest radiator, is fitted with an overflow, for water expands as it is heated. If the expansion tank is closed so that the overflow pipe will not open except under pressure after the air in the tank has become compressed by the expansion of the water, a higher temperature in the pipes may be reached, but such a furnace must be given more careful attention than one with an open expansion tank. Learn to know the parts of a heating system and how they operate before trying to manage it.

68. Water. Fill the boiler and radiators full of water, and add enough more to partly fill the expansion tank. From time to time, note the height of water in the tank, to know if more must be added. Do not add water when unnecessary, as fresh water tends to rust pipes faster than water from which the carbon dioxide and air have been exhausted. To note the height of water, read the gage.

If there is much sediment in the water used, this must be drawn off from the bottom of the boiler to prevent its accumulating there. When this is done, fresh water must be added to replace the water drawn off. Loss of water from evaporation must also be replaced. No water should be put into the system except to replace such loss. Do not draw the water out of the system, and refill it from time to time. The practice of changing the water in the furnace rusts it more than keeping the same water in it all the time.

69. Radiators. Radiators (B, Fig. 31) are made of rather complicated coils of pipe, so often an accumulation of air lodges in them. This interferes with the circulation of the water and the radiator does not get hot. There usually is a vent (A and B, Fig. 33) attached to each radiator to let out air which collects there. If a radiator does not heat well, open the air vent until the air ceases to flow from it and water comes; then close it. Valves should be placed at places where cold water collects in bad plumbing.

In very cold weather, do not entirely shut off the valve of the pipe leading to any radiator, as the circulation of a little warm water is needed to keep it from freezing. Radiators may be placed under the floor (Fig. 34) when so desired.