Abstract: A coil tube heater for a multi-oil burner in a used-oil fired furnace utilizing an air to liquid heat exchanger and being fabricated from tubing formed into a tightly coiled cylinder having a plurality of coil loops that are not fixed to any of the adjacent loops to allow for unfettered heat expansion. The coil tube heater is provided with a ceramic sleeve interposed between the burner assembly and the coiled heat exchanger to focus the flame into a tight configuration toward the target positioned at the rear of the combustion chamber. The coil tube heater is provided with a circulation system that has a first circulation loop having a first circulator that moves a liquid transfer medium through the coiled heat exchanger to a buffer tank or directly to the load.

Abstract: A preheater block for a multi oil furnace is disclosed wherein the metallic preheater block is formed with a separate heater chamber housing a heating element to provide conductive heat throughout the preheater block which is provided with a first flow path defining multiple passes through the preheater block to raise the temperature of the flow of used oil therethrough to a predetermined level. An oil flow regulator is coupled to the first flow path to permit a manual regulation of the rate of oil flow through the preheater block after the used oil has attained the predetermined temperature. A second flow path is defined within the preheater block to allow a flow of compressed air therethrough to reach substantially the same predetermined temperature as the used oil.

Abstract: A multi oil furnace is disclosed wherein the external cabinet shell houses a central burner chamber, an upper bank of conduits and a lower bank of conduits. Headers operably coupling the burner chamber, the upper and lower banks of conduits and a discharge opening define a flow path for the combustion gases created by the ignition of the used oil within the burner chamber. A ventilation chamber positioned between forward and rearward headers allows the passage of ambient ventilation air around the conduits and the burner chamber to effect a transfer of heat from the exhaust gases to the ventilation air while maintaining isolation therebetween.

Abstract: Service doors for a multi oil furnace to improve serviceability are disclosed wherein the multi oil furnace is provided with a hinged front door to provide access to the burner chamber and heat exchanger, while a burner housing is pivotally mounted to the front door to permit movement thereof to gain access to the burner assembly without requiring dismantling of the burner assembly, the burner housing or the front door. A connecting line delivering a flow of used oil to the burner assembly is provided with a rotatable coupling mounted in line with the pivot axis of the burner assembly so that the burner assembly can be accessed for service with a minimum of inconvenience. A power cable delivering electrical power to the burner assembly is mounted such that disconnection of the power cable is required when either the burner housing or the front door is pivotally moved for service of the various components of the multi oil furnace.