Abstract: A multi-oil fired furnace having a heat exchanger that extends rearwardly of the combustion chamber and utilizes laminar air flow around the combustion chamber to minimize the width and height dimensions of the cabinet shell for the furnace. The heat exchanger includes an exhaust header having a central opening and a cluster of concentrically arranged exhaust tubes connected to the combustion chamber. A vertical baffle forces the flow of air through a central opening that is concentric with the combustion chamber into a group of horizontal baffles directing the air into a generally laminar flow pattern against the outer surface of the combustion chamber before being discharged from the cabinet shell in a selected one or more of three possible directions. The fan control switch is mounted on a mounting plate that is welded to the combustion chamber to provide a planar contact surface for the switch mechanism.

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 retention head for the end of the burner nozzle housing on a waste oil furnace controlS the flow of combustion air relative to the flame produced by the burner nozzle. The retention head is formed as a cup-shaped member that mounts in a detachable manner on the outside of the burner nozzle housing. The retention head has an operative face having a central opening through which a portion of the combustion air can flow and support the flame passing through the opening. A solid ring defining the central opening forces air into circumferential vented slots around the perimeter of the retention head. The vented slots have angled flaps that direct the combustion air into a spiraled flow pattern circumferentially around the flame. The retention head has an inwardly curved periphery to help direct combustion air into an inward pattern surrounding the flame.

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: A heat exchanger for a multi oil furnace is disclosed wherein the external cabinet shell houses a central ventilation chamber divided into inlet and outlet sides by a generally vertical barrier. Combustion gases flow from the burner chamber into an upper bank of conduits and a lower bank of conduits, all of which pass horizontally through the ventilation chamber. 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. By positioning the burner chamber vertically between the upper and lower banks of conduits, the ambient ventilation air must pass over the burner chamber and the upper and lower banks of conduits twice while passing through the ventilation chamber, thereby providing a 360 degree loop of heat exchange.

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.

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.

Abstract: A compartmentalized housing for the operative components of a multi oil furnace is disclosed wherein the first housing compartment contains an integrated preheater block and operative controls for the flow of used oil and compressed air to the burner assembly, which is cantilevered from the preheater block and positioned within the second housing compartment. The second housing compartment rotatably supports a combustion air fan to draw combustion air through an inlet opening in the second housing and blow the combustion air into the burner chamber over the burner assembly, which is configured and oriented to minimize combustion air turbulences. The fan motor is supported within the third housing compartment. Each of the housing compartments is provided with a removable cover to permit access to the respective component housed therein.