Forced-Warm-Air Heating Systems
A forced-warm-air heating system (Figure 6-5) consists of a furnace equipped with a blower, the necessary controls, an air-duct system, and an adequate number of suitably located warm-air
DRAFT REGULATOR IN SMOKE PIPE
GRAVITY-TYPE FURNACE FORCED-WARM-AIR FURNACE
Figure 6-6 Duct arrangement for gravity and forced-warm — air furnaces.
Registers and cold-air returns. The warm air travels from the furnace through the supply ducts to the room registers. The cold air returns through the return to the furnace, where it is reheated and recirculated. The return-air ducts are joined together before reaching the furnace, a feature distinguishing the duct arrangement in this type of heating system from that found in heating systems relying upon the gravity flow principle of air circulation (Figure 6-6).