Furnace with combustion air-cooled draft inducer fan

A fuel-fired, forced draft heating appliance comprising:

• a chamber having an exterior wall with an air intake opening therein;
• a heat exchanger;
• a fuel burner disposed in said chamber and operative to create hot combustion products in said heat exchanger;
• a draft inducer fan disposed in said chamber, having a motor, and being operative to forcibly expel flue gas from said heat exchanger;
• an air transfer structure extending through said chamber, having an interior flow passage, and being interconnected between said air intake opening and said motor,
• operation of said draft inducer fan creating within said chamber a negative pressure that draws combustion air into said chamber, for delivery to said fuel burner, sequentially through said air intake opening, through said interior flow passage, and against said motor in a manner cooling said motor and being preheated by said motor prior to delivery to said fuel burner;
• and
• a baffle structure positioned adjacent said fuel burner and being operative to shield said fuel burner from flicker-creating impingement by combustion air discharged from said interior flow passage for delivery to said fuel burner.

A method of operating a fuel-fired, forced draft heating appliance including a chamber having an exterior wall with an air intake opening therein, a heat exchanger, a fuel burner disposed in said chamber and operatively associated with said heat exchanger, and a draft inducer fan disposed in said chamber, having a motor, and being operative to forcibly expel flue gas from said heat exchanger, said method comprising the steps of:

• providing an enclosed combustion air passage extending through a portion of said chamber between said air intake opening and said motor, and, during operation of said heating appliance:
• cooling said motor, and supplying preheated combustion air to said fuel burner, by sequentially flowing combustion air into said air intake opening, through said combustion air passage, against said motor, and outwardly from said enclosed combustion air passage,
• said fuel burner, during operation thereof, generating a flame exposed to said chamber, and
• said method further comprising the step of shielding said flame from flicker-creating impingement thereon by combustion air delivered to said fuel burner.

A draft inducer fan for use with a fuel-fired heating appliance, comprising:

• a hollow body having an inlet, an outlet, and an outer side portion;
• an impeller disposed within said hollow body;
• a motor projecting outwardly from said outer side portion;
• a drive shaft coupled to said motor and drivingly coupled to said impeller;
• an auxiliary fan blade structure drivably coupled to said drive shaft adjacent said motor;
• and
• an air transfer housing structure having spaced apart inlet and outlet openings and an interior in which said motor and said auxiliary fan blade structure are at least partially disposed, said air transfer housing structure permitting combustion air to be flowed therethrough between said inlet and outlet openings to contact, cool and be preheated by said motor,
• said auxiliary fan blade structure, during driven rotation thereof, functioning to turbulate combustion air passing through said air transfer housing structure in a manner facilitating heat exchange contact between the combustion air and said motor.