Abstract: A multi oil furnace is disclosed wherein the front door is sealable against the burner chamber and against a lip extending around the circumference of a front header formed in the cabinet shell to operatively interconnect an upper bank of heat exchanger conduits with a lower bank of heat exchanger conduits. The exhaust gases flow from the burner chamber into the upper bank of conduits to the front header where the exhaust gases must flow around the burner chamber to the lower bank of heat exchanger conduits. The lip extending around the periphery of the front header is recessed below the lower bank of conduits to permit an accumulation of ash precipitated from the exhaust gases. The front door carries longitudinally offset sealing surfaces to seal against both the burner chamber and the header lip. Both the upper and lower banks of conduits, the burner chamber and the front header are accessible through the opening corresponding to the front door when moved to its opened position.