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Heating, Lighting, and Refrigeration: Furnaces

Furnaces. - Furnaces vary greatly in the amount of coal that they con- G "Most Notable is the Underfeed System." sume to produce a given temperature.

At best only a small percentage of HEATING, LIGHTING, AND REFRIGERATION the actual heat value of the fuel is realized, and the future will doubtless witness great improvement in this direction. At present a number of new devices are on the market, of which one of the most notable is the underfeed system. This furnace is so constructed that the fuel is deposited in a chamber below the fire box, where it is gradually warmed before being forced from below by means of a lever into the fire box. Thus the heat is saved which is wasted in other types of furnaces by raising the temperature of cold fuel thrown directly upon the blaze, and less fuel is consumed to produce a given increase of temperature. There is also less unnecessary combustion. The difference may be illustrated by the burning of two candles, one right side up and the other upside down. The former con- "An Inevitable Waste." sumes no more fuel than is necessary; the latter produces an inevitable waste.

Another device consists in a perforated plate of metal, placed across the fire box so that the flame is broken up into a large number of small jets of burning gas. The plate also becomes exceedingly hot and thus assists the combustion of the gases.

Other important devices are means to prevent heat from being wasted by radiation in the cellar or basement or by escaping up the chimney. The indirect-draught furnace contains a device which causes the heated products of combustion to circulate in such a way, before going up the chimney, as to heat every part of the furnace.