A manual of home-making

water system is installed means of removing foul air are more frequently provided, dther l>y vent starks leading into the attic or through the roof, with register openings in different rooms, or by open grates, the floes for which can be equipped with damp- ers to regulate the removal of fou! air. The sytitem some- times fails to work satisfactorily if provii^ion is not made for the escape of foul air from a room, as the fresh warm air will not con- tinue to flow in unless an equal amount escapes. The first cost of heating liy the hot-air furnace is less than that of either the steam or the hot-water system, but to maintain e<:iual tempera- ture conditions may require the burning of more fuel, whether the furnace heats air taken from outdooi's or reheats air al- ready in the house. Evidently, reheating air will require less fuel, and eonse<|uently less attention to the furnace, tlian Ideat- ing fresh air, but the ventilation will not In* gmuL In hcjuies heated by steam or hot water, the method of heating, whether direct or indirect, and the provision, if any, for removing foul air will affect the consumption of fuel, which will vaiy with the percentage of tin* total radiation that is indirect and with the amount of warm air removed througli vent stacks or grates. A furnace-heating system maintains a less even temperature because less heat is stored in it. In this rci^pect, hot-water heating has a distinct advantage over l>oth steam and hot air because the large quantity of water in the boiler, pipes, and radiators can maintain the temperature throughout the house for a considerafjle time after the fire dies down. In addition, the maintenance of an even temperature in mild weather is easier with the hot-water system because the temperature of the water in the radiators, hence the amount of heat given off, can be controlled within wide limits. Size of bailer and furnace* If to supply the necessar>^ heat requires the consumption 20 pounds of fuel an hour and the boiler or funiace is to keep this up for eight hours without attention, it is evident that the fire pot must be large enough to hold 160 pounds of fuel, and in addition tlie quantity necesi>ary to rekindle a fresh charge, 4 HEAT AND LIGHT this qoantity being: ordinarily assumed to be 20 per cent of the quantity of fuel in the fire pot after the firing, or in this case 40 pounds, Henee the fire pot must hold 200 pounds of fuel and still leave space for combustion. If anthracite coaL bituminous coal, and coke are available and each ha^s such heatinp; value that 20 pounds of it will be required an hour to supply heal, the tire-pot space occupied by an eight-hour charge of each fuel may be figured by dividing 200 by the weight a cubic foot of each fuel the space thus cal- culated being approximately 3,6 cubic feet for anthracite, 4.0 cubic feet for bituminous coal» and 5.7 cubic feet for coke. Therefore, if the fire pot were designed for anthracite, it would hold coke enough for a firing period of ai>proximatcly five hours instead of eight.