FURNACE WITH COMBUSTION AIR-COOLED DRAFT INDUCER FAN

A fuel-fired, forced draft air heating furnace is provided with a draft inducer fan structure which substantially reduces the operational noise of the furnace. The draft inducer fan is disposed within a sealed burner vestibule area of the furnace and is provided with an auxiliary fan blade structure mounted on its drive shaft in a spaced relationship with its main fan impeller. The auxiliary fan blade structure and the fan motor are disposed within an open-ended air transfer duct structure coupled to an air inlet opening in an exterior wall portion of the vestibule. During operation of the draft inducer fan, combustion air is drawn inwardly through the transfer duct structure, across the inducer fan motor, and into the vestibule for supply to the furnace burner section. The use of the transfer duct structure and auxiliary fan blade structure serves to cool the fan motor, preheat the combustion air, and reduce the overall operational noise of the furnace. A baffle plate member is placed in a shielding relationship with the burner structure to inhibit burner flame flickering that might otherwise be caused by combustion air impingement with the burner flames.