Abstract: 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.

Abstract: A multiple inshot-type gas burner structure is formed from a pair of facing, intersecured stamper sheet metal plates. A spaced plurality of parallel, rectangularly cross-sectioned burner bodies are defined by facing triangular indentation pairs in the plates and have, at front outlet end portions thereof, side indentations which serve to mix air and gaseous fuel received at rear end portions of the burner bodies, and to divert a portion of the fuel/air mixture into crossover channels intercommunicating front interior portions of the burner bodies. The crossover channels have central arcuate closed portions that cooperate with progressively sized standoff dimples extending between opposite wall portions of the channels to provide an even crossover flame pattern along the outlet slot section of each channel.

Abstract: A fuel fired, forced air, draft induced heating furnace is provided with NOx reduction apparatus associated with a plurality of combustor tubes forming a portion of its heat exchanger structure. In-shot type fuel burners are spaced apart from and face the open inlet ends of horizontal combustion sections of the combustor tubes. The NOx reduction apparatus includes a plurality of insert members received in inlet end portions of the combustor tubes. Each insert member is formed from a single sheet of metal mesh material and has a hollow, open-ended body portion coaxially received in its associated combustor tube and spaced laterally inwardly from its interior side surface, and a circumferentially spaced plurality of integral, laterally outwardly projecting support rib portions that slidably engage the interior side surface of the combustor tube, thereby automatically maintaining the insert member in a coaxial relationship with the combustor tube regardless of the positional orientation of the tube.