Document VjMxxobmZpD7Bn2m0EaVmO4Bq

Heating Ventilating Air Conditioning Guide 1939 the quantity of oil in the storage tank. For this purpose various types or indicating or recording gages are used, the simplest forms being the gl^ level gage, and a float-and-dial arrangement having a graduated dial faCe indicating the proportion of the tank containing liquid. Other more accurate and dependable devices are designed to operate by hydraulic action or by hydrostatic impulse. These instruments may be attached to the tank, giving a direct reading of'the liquid contents; or the instrument itself may be located at a convenient point remote from the tank and connected with the tank by pipe or tubing. The quantity readings may be in gallons of liquid, height of liquid level in feet and inches, or in other desired units of measurement. GAS-FIRED APPLIANCES The increased use of gas for. house heating purposes has resulted in the production of such a large number of different types of gas heating systems and appliances that today there is probably a greater variety of them than there is for any other kind of fuel. Gas-fired heating systems may be classified as: follows : L Gas-Designed Heating Systems. A. Central Heating Plants, 1. Steam, hot water, and vapor boilers. 2. Warm air furnaces. B. Unit Heating Systems. 1. Warm air floor furnaces. 2. Industrial unit heaters. 3. Space heaters. 4. Garage heaters. II. Conversion Heating Systems. . A. Central Heating Plants. , 1. Steam, hot water and vapor boilers. 2. Warm air basement furnaces. These systems are supplied with either automatic or manual control. Central heating plants, for example, whether gas designed or conversion systems, may be equipped with room temperature control, push-button control, or manual control. Gas-Fixed Boilers Information on gas-fired boilers will be found in Chapter 13.: Either ~ snap action or throttling control is available for gas boiler operation. This is especially advantageous in straight steam systems because steam pressures can be maintained at desired points, while at the same time complete cut-off of gas is possible when the thermostat calls for it. Gas-Fired Warm Air Furnaces Warm air furnaces are variously constructed of cast-iron, sheet metal and combinations of the two materials. If'sheet metal is used, it must be of such a character that it will have the maximum resistance to the corrosive effect of the products of combustion. With some varieties of manufactured gases, this effect is quite pronounced. - Warm air furnaces 226 Automatic Fuel Burning Equipment htainable in sizes from those sufficient to heat the largest residence oDto sjzes applicable to a single, room. The practice of installing a ^ ggpayate furnaces to heat individual rooms is peculiar to mild nr "tes Small furnaces, frequently controlled by electrical valves d'^ted ky push-buttons in the room above, are often installed to heat actua_ where heat may be desired for an hour or so each day.- These fJmices are used also for heating groups of. rooms in larger residences. I a system of this type each furnace should supply a group of rooms in TTch the heating requirements for each room in the group are similar as f^r'as the period of heating and temperature to be maintained are con cerned. . The same fundamental principle of design that is followed in the con struction of boilers, that is, breaking the hot gas into fine streams so that all particles are brought as close as possible to the heating surface, is equally applicable to the design of warm air furnaces. Codes for proportioning warm air heating, plants, such as that formu lated by the National Warm Air Heating and Air Conditioning Association are equally applicable to gas furnaces and coal furnaces. Recirculation should always be practiced with gas-fired warm air furnaces. It not only aids in heating, but is essential to economy. Where fans are used in con nection with warm air furnaces for residence heating, it is well to have the control of the fari and of the gas so coordinated that there will be sufficient delay between the turning on of the gas and the starting of the fan to prevent blasts of cold air being blown into the heated rooms. An additional thermostat in the air duct easily may be arranged to accomplish this. Floor Furnaces Warm air floor furnaces are well adapted for heating first floors, or where heat is required in only one or two rooms. A number may be used to provide heat for the entire building where all rooms are on the ground floor, thus giving the heating system flexibility as any number of rooms may be heated without heating the others. With the usual type the register is installed in the floor, the heating element and gas piping being suspended below. Air is taken downward between the two sheets of the double casing and discharged upward over the heating surfaces and into the room. The appliance is controlled from the room to be heated by means of a control lever located near the edge of the register. The handle of the control is removable as a precaution against accidental turning on or off of the gas to the furnace. Space Heaters Space heaters are generally used for auxiliary heating, but may be, and are in many cases, installed for furnishing heat to entire buildings. With the exception of wall heaters, they are portable, and can be easily removed and stored during the summer season. Although they should be connected with solid piping it is sometimes desirable to connect them with flexible gas tubing in which case a gas shut-off on the heater is not permitted, and only A.G.A. approved tubing should be used. Parlor furnaces or. circulators are usually constructed to resemble a caDinet radio. They heat the room entirely by convection, i.e., the cold air of the room is drawn in near the base and passes up inside the jacket. 227