Abstract: The present invention involves a combustion box of a gas furnace which experiences oscillating combustion. The combustion box employs an opening in the housing which is tautly covered with a diaphragm made of elastic material such as silicone rubber. The elastic diaphragm transmits noise and vibration generated by the oscillating combustion of the gas burners in the combustion chamber and thereby dissipates that vibration and noise.

Abstract: A tubular recuperative heat exchanger structure is mounted in a housing chamber within a fuel-fired condensing furnace in the vertical flow path of supply air being flowed through the housing by a blower. The heat exchanger structure comprises a primary heat exchanger defined by a vertically serpentined series of combustor tubes into open inlet ends of which a series of inshot-type fuel burners flow flames and hot combustion gases, and a secondary heat exchanger formed from a horizontally extending series of finned heat exchanger tubes having inlets in flow communication with the outlets of the combustor tubes and outlets in flow communication with the inlet of a draft inducer fan.

Abstract: A heat recovery apparatus for increasing the efficiency of a furnace having a cold air return, a burner, a hot air outlet, and a hot air exhaust. The heat recovery apparatus comprising a finned coiled heat exchanger located in the exhaust and having a water inlet and a water outlet. The water outlet connected via a silicone tube to a second water inlet on a core heat exchanger located in the cold air return. The core heat exchanger having a water outlet connected via second silicone tube to a water reservoir tank. The water reservoir tank containing water and a pump submerged within the water. The pump having a third water inlet and a third water outlet. The third water outlet being connected via a third silicone tube to the water inlet of the coiled heat exchanger. The heat recovery apparatus increasing the efficiency of a non-high efficiency furnace.

Abstract: An improved two-stage combustion chamber for burning waste hydrocarbons such as crank case oil, spent motor oil, transmission fluid, lubrication dopes, and heavy bodied gear lubes. The combustion chamber is formed from a plurality of spaced apart, stacked annular rings that form a flame containment housing having superheated surfaces. The flame containment housing contains the flame of an atomizing oil burner suitable for burning the variable viscosity waste hydrocarbons. The annular rings include outer walls and inwardly extending flanges that intercept unburned fuel droplets and combustion byproducts, vaporizing the droplets and/or stimulating secondary combustion. The annular rings are removable and replaceable, and are supported in spaced-apart relation by spacers on a plurality of support rods.

Abstract: A method of connecting a heat exchanger to a forced air furnace is described. Firstly, connect a valve to the hot exhaust gas outlet of a furnace. The valve has a generally "L" shaped valve body. The valve body includes a primary passage. A diversion passage intersects the primary passage. A diversion return port intersects the primary passage downstream of the diversion passage. A butterfly valve member is pivotally mounted at the intersection of the primary passage and the diversion passage. The valve member has a first wing and a second wing. The valve has an open position and a closed position. The valve member is normally in the open position. Secondly, connect a fresh air outlet of a heat exchanger to a fresh air inlet on the furnace.

Abstract: In a dwelling having a forced warm air type central heating system in which the source of heat is the hot gas products of combustion in a furnace, ambient fresh air is introduced into the dwelling to improve the quality of air in the dwelling by a fresh air input duct to the fresh air input of a relatively low temperature flue gas to the fresh air heat exchanger so that the fresh air is warmed and the fresh air output of the heat exchanger is connected by a duct to the forced warm air heating system so that the warmed fresh air is entrained with the air in the system. In a preferred embodiment, the flue gas to fresh air heat exchanger is attached to a section of the furnace flue pipe that is covered by a thermally conductive gas barrier and includes an enclosure for enclosing the outside barrier covered surface of the section of the furnace flue pipe forming an annular space between the gas barrier and the enclosure through which the fresh air flows and is warmed by heat from the flue gas.

Abstract: An indirect heater for heating air to be used for drying, curing or heating having an enclosure housing a circulation fan, filter bank, heat exchanger module and a burner. The heat exchanger has a bundle of tubes received between a pair of spaced apart headers. A cylindrical burner tube extends through one header and the tube bundle and opens into the other header. The burner flame and gaseous combustion products are discharged into a replaceable sacrificial sleeve that is telescopically received in the burner tube. A fan recirculates the heated gases through the interior of the sleeve, burner tube and the tubes of the bundle to increase heat transfer to the exterior air. The enclosure has a base, two pairs of opposed sidewalls and a top wall overlying the sidewalls. Each sidewall has an inner skin, a framework of trusses, an outer skin and insulation between the skins.

Abstract: In a gas-fired furnace of the type having a manifold assembly, comprising a gas valve, a manifold, orifices extending from the manifold and located on a common line, and a gas control assembly having a burner box compartment, the improvement comprises an apparatus for attaching a manifold assembly to the burner box compartment. The apparatus comprises a plurality of brackets, each bracket being affixed to the manifold at a position essentially 180.degree. from the common line of orifices, and essentially perpendicular to the common line; each end of the bracket is retained near opposite side of the opening of the burner box compartment, and one end of each bracket is affixed to the side wall of the burner box.

Abstract: There is disclosed a furnace having an air flow path for heated air and combustion products that passes through a condensing heat exchanger. Condensate forming in regions of negative and positive pressure is separately conducted to a unitary condensate trap of minimal vertical height incorporating therein separate traps for handling the high and low pressure gaseous environments. The condensate is drained through a common outlet port into the atmosphere or into a drain pipe.

Abstract: A burner assembly for a gas furnace includes an elongated support member and a number of individual burners. The support member includes consecutive yoke sections for receiving a corresponding burner and shelves for supporting a flange segment formed around the periphery of each burner. Each flange segment of the burners includes a pair of mounting apertures which receive bendable tabs provided on the support member when the burner is positioned within a corresponding yoke section and supported by consecutive shelves. When the tabs are bent over, the individual burners are secured to the support member. The support member also includes mounting ears for quickly mounting and removing the burner assembly to a bracket provided in the burner box of the gas furnace.

Abstract: A pair of sealing skirts join the inducer to the collector box of a condenser induction furnace, and accommodate offset in positions of the inducer inlet opening and the collector box outlet port. The two mating skirts are congruent and of generally triangular shape. A ridge or lip of one fits a groove on the other to form an airtight gasketless seal.

Abstract: A furnace of the type for supplying circulating heated air to an comfort space, the furnace being contained within a cabinet, having a door allowing access to the interior thereof, which is set in a door frame, wherein the furnace is capable of operating in at least any vertical orientation, an improvement comprising. The bottom end of the door is removably retained against a bottom portion of the door frame, via a hinge, when the furnace is any vertical orientation. At least one latch is located adjacent the top end of the door when the furnace is in any vertical orientation, the latch being constructed to engage a mated door strike; and at least one door strike is located in both a top portion and a bottom portion of the door frame.

Abstract: The present invention involves a gas furnace having a condensate trap formed in the transition box between the secondary heat exchanger and the exhaust blower. The gas furnace includes gas burners which burn fuel within the passageways of the heat exchanger are induced through its internal passageways by an exhaust blower. The transition box connects the heat exchangers with the exhaust blower and provides a location for condensate to collect for discharge through the integral condensate trap assembly. Also, the exhaust blower housing has drainage ports to convey condensate from the blower and vent back to the condensate trap.

Abstract: In a furnace of the type having a blower shelf with a blower attached to one surface thereof and a heat exchanger unit located proximate a second surface thereof, and the heat exchanger unit being reversibly attachable to the blower shelf, the improvement comprising: a retaining structure unitary with the back panel of the heat exchanger; and a structure which mates with the retaining structure and is unitary with the blower shelf. The retaining structure and mating structure function jointly to retain the back panel of the heat exchanger unit perpendicular to and proximate the blower shelf.

Abstract: A single forced air furnace (10) may be installed in any of an upflow, downflow, or horizontal airflow orientation, with discharge of flue gases either opposite to or concurrent with the primary airflow path. The combination of design features which provides this versatility includes the following features: an inducer assembly (24) for withdrawing flue gas from the furnace heat exchanger (20), which inducer assembly (24) may be positioned to direct the discharge of flue gas in a selected one of a plurality of directions; an optional internal flue duct (64) for directing the flue gas through the furnace vestibule chamber then through the furnace housing (12); and the fact that the furnace housing (12) is dimensioned and configured so that the furnace may be supported on any one of four different sides (O, I, S.sub.1, S.sub.2) of the furnace housing (12).

Abstract: A fuel-air combustion chamber with improved mounting and thermal distribution features. The combustion chamber is formed with a flange adapted for receiving a plurality of retainer rings therearound for direct securement of the flange to a burner mounting plate adjacent a fuel-air nozzle for generating heat within the combustion chamber. The combustion chamber is also temporarily supported within the furnace housing by a combustible support leg affixed thereto. In this manner, the combustion chamber is supported during shipping and handling by a support leg which is automatically disintegrated during use of the combustion chamber.

Abstract: A wall furnace is disclosed in which a secondary heat exchanger is provided to maximize the heat transfer efficiency of the furnace. The secondary heat exchanger faces the room to be heated but is aligned directly behind the primary heat exchanger. The length of the secondary heat exchanger is shortened as compared to the combined length of the combustion chamber and primary heat exchanger so as to reduce inefficiencies due to reheating of the combustion gases and to promote air flow and heat transfer around the secondary heat exchanger. Thus, this configuration provides for two essentially separate circulation circuits for heat transfer and maximum furnace efficiency. Separate heated air deflectors are also provided for each of these circuits. A side venting draft hood is also disclosed.

Abstract: A furnace including an elongated housing having an air intake adjacent one end of the housing and an air discharge vent adjacent the other end of the housing utilizes a substantially U-shaped heat exchanger positioned within the housing and a partition supported within the housing so as to separate the interior of the housing into first and second zones. A fuel burner assembly directs a flame and attending combustion products into one leg section of the heat exchanger so that the heat generated by the flame and combustion products are absorbed through the inside surfaces of both leg sections. The furnace also includes a fan so that a fraction of the air move through the first zone and absorbs heat from the outer surfaces of the one leg section and so that a remainder of the air moves through the second zone and absorbs heat from the other surfaces of the other leg section. The partition provides a first and a second opening through which the first and second zones communicate with one another.

Abstract: A method to prevent freezing of water in a conduit that carries the water out of a building. The method uses a device that alternately accumulates the water in a container and then dumps it. The water is then carried to the outside of the building through a conduit. The water, being released in batches, does not have time to freeze in the conduit.

Abstract: A furnace includes at least one heat exchanger with first and second plate members secured together to define passageways that form serpentine flow paths between an inlet passageway and an outlet passageway. The inlet passageway receives hot products of combustion from a burner which extends into it. A blower induces the flow of the combustion products through the heat exchanger. A second blower induces the flow of air over the surfaces of the exchanger.

Abstract: A fuel-fired forced air condensing furnace has installed therein a recuperative heat exchanger assembly with a primary heat exchange section operative, during furnace operation, to transfer sensible combustion gas heat to air being flowed through the furnace, and a secondary heat exchange section operative to transfer latent combustion gas heat to the air. The secondary heat exchange section includes a finned tube heat exchanger structure extending between spaced apart combustion gas inlet and outlet collector boxes.

Abstract: A pilot pressure switch for a furnace detects the fluid pressure within the pilot line for a pilot flame, and upon the fluid pressure in the pilot line exceeding a predetermined value, an electrical signal from a thermostat may be passed to a furnace blower control to operate the furnace main blower and furnace vent blower.

Abstract: In a multi-poise furnace having multiple parallel heat transfer stages, each stage having superimposed flow passages lying in a common plane. The last passage in each stage containing laterally-disposed indentations in opposed side walls for increasing the heat transfer surface area, and the walls of the last passage being further configured to conduct any condensate formed in the heat exchanger out of the exit region of the exchanger, regardless of the furnace orientation.

Abstract: A coupling box for a condensing furnace having primary and secondary heat exchangers places the discharge ports of the primary heat exchanger in fluid communication with the inlet ports of the condensing heat exchanger. A baffle in the coupling box directs the flow of flue gas evenly therein to maintain temperature equilibrium so that water vapor does not condense in the coupling box.

Abstract: A cell panel for a gas furnace having a burner box containing combustion burners includes burner target plates formed by an extrusion process from the sheet material forming the cell panel. The burner target plates include a concave side positioned to face the discharge side of a corresponding burner, and a convex side upon which the flared inlet port of a corresponding heat exchanger cell may be securely seated.

Abstract: A furnace for supplying circulated heated air to a comfort zone, the furnace having a condensing heat exchanger and a blower for moving ambient air over the heat exchanger, wherein a transformer for stepping down line voltage (115 VAC) to control voltage (24 VAC) is secured to the inner surface of an enclosed housing within the furnace wherein the inner wall also supports at least one retaining bracket and one fastenable support bracket. A first flange extending from the transformer engages the retaining bracket to rotatably support the transformer. A second flange extending from the transformer engages the fastenable support bracket to secure and further support the transformer supported within the housing. A threaded member secures the fastenable support bracket to the second flange, thereby preventing disengagement.

Abstract: An inducer (40) for causing a flow of combustion air into and gases of combustion through and out of a furnace (10) of the condensing type. The inducer is intended for use, without modification of its design or size, in a series of furnaces of the same basic design but having different heating capacities and therefore different requirements for flow through the induction flow path. The furnace design is such that a given furnace is capable of operation so as to provide a flow of air to be heated that is either up, down or horizontal with only minor field modification on installation. The inducer has two discharges (43), only one of which is used in a given installation. The other discharge is blocked with a plug (61) of special configuration that can vary the output of the inducer to ensure optimum flow of combustion air into and gases of combustion through and out of the furnace.

Abstract: An abatement member for inhibiting formation of oxides of nitrogen in a gas-fired furnace by controlling peak flame temperatures and residence times at the peak flame temperatures is described. The combustion system has at least one heat exchanger conduit having a flow path therethrough and at least one gas burner for burning fuel to produce a combustion flame. The abatement member has a porous refractory body portion having at least one section which is disposed transversely to the direction of flow of gases through the conduit. In one embodiment, the abatement member is a metallic screen having a serpentine shape and positioned within the fire tube. The combustion flame is directed toward and into the inlet of a fire tube and through the screen whereby the screen absorbs thermal energy from the combustion flame at a rate which limits peak flame temperatures to levels which inhibit formation of oxides of nitrogen.

Abstract: In a fixed-firing rate induced draft furnace, having a heat exchanger and an integrated control inducer motor, an improved method of controlling excess air comprising the steps of: providing at least one pressure switch that is responsive to a preselected pressure drop level in the heat exchanger, the pressure drop level being selected so as to be commensurate with a theoretically desired excess air level under firing operating conditions; accelerating the integrated control inducer motor until the pressure switch closes and thereupon recording a first motor speed and a first current level; calculating a first torque value based on the first motor speed and the first current level; and regulating torque applied to the integrated control inducer motor in accordance with the first torque value.

Abstract: A front access door suitable for accessing and enclosing a housing within a multipoise furnace functions in conjunction with a safety shutoff switch to provide greater access and safety when assembling and servicing the furnace. The front access door is hingably supported upon the bottom wall of the housing for removal from the furnace and rotation between a closed position and an opened position. The shutoff switch is mounted outside the housing on the top housing wall. When the access door moves into a closed position, a switch activator, mounted to the access door, passes over the top housing wall and closes the switch, thereby allowing power to flow to a blower within the housing. When the access door is moved into an open position, the switch activator opens the switch, thereby terminating power to the blower.

Abstract: A tubular recuperative heat exchanger structure is mounted in a housing chamber within a fuel-fired condensing furnace in the vertical flow path of supply air being flowed through the housing by a blower. The heat exchanger structure comprises a primary heat exchanger defined by a vertically serpentined series of combustor tubes into open inlet ends of which a series of inshot-type fuel burners flow flames and hot combustion gases, and a secondary heat exchanger formed from a horizontally extending series of finned heat exchanger tubes having inlets in flow communication with the outlets of the combustor tubes and outlets in flow communication with the inlet of a draft inducer fan.

Abstract: A method and apparatus for preventing splashing condensate from activating the safety pressure switch in a multi-poise condensing furnace includes removing the existing tubing connected to upper and lower pressure taps provided on the collector box of the furnace. T connectors and secondary tubing are then fastened to each of the pressure taps and the existing tubing reconnected to a corresponding T connector.

Abstract: An induced flow condenser furnace has a combustion air intake shoe that connects the combustion air pipe to the burner box, and has a provision for draining off any condensate from the combustion air pipe before it reaches the burner box. The shoe has a tray portion with an open top that mates with an intake opening in one wall of the burner box, and a tube portion that connects at one end with the combustion air pipe and at the other end with an end cap. The latter has a drain nipple to permit escape of the condensate. An internal lip is formed in the tube portion traps condensate when the furnace is poised in an inverted or downflow orientation. This permits the furnace to be poised in any of four orientations. The intake shoe facilitates connection of the inlet pipe and drain tube in all multi-poise configurations.

Abstract: There is disclosed a furnace having an air flow path for heated air and combustion products that passes through a condensing heat exchanger. Condensate forming in regions of negative and positive pressure is separately conducted to a unitary condensate trap of minimal vertical height incorporating therein separate traps for handling the high and low pressure gaseous environments. The condensate is drained through a common outlet port into the atmosphere or into a drain pipe.

Abstract: An upflow or downflow furnace comprising a housing; a heat exchanger section in the housing, a blower section in the housing, and a blower deck in the housing having an upward side and a downward side. The heat exchanger section includes at least one heat exchanger and the blower section includes a blower for moving air through the heat exchanger section. The blower deck separates the blower section and the heat exchanger section. The blower deck includes an aperture and means, in proximity to the aperture, for either mounting the blower to the downward side of the blower deck for an upflow furnace configuration or mounting the blower to the upward side of the blower deck for a downflow furnace configuration.

Abstract: A forced air furnace (11) has a heat exchanger (35) with one or more tube pack assemblies (10). Each tube pack assembly (10) has a burner (21) situated to fire into a primary fire tube (30) which is mechanically connected through a transition cap (36) to a plurality of secondary tubes (37, 38, 39, 41) returning combustion products from the primary fire tube (30) to a collection manifold (24) at the intake end of a draft inducer assembly (23) for discharge of the combustion products to a flue. In the preferred embodiment, the transition cap (36) is connected to the primary fire tube (30) and to the secondary tubes (37, 38, 39, 41) by a mechanical interlock.

Abstract: A heating furnace is provided with a counterflow heat exchanger defining serpentine up flow fresh air passages and downflow combustion products passages. The exchanger is of sheet metal modular construction.

Abstract: An induced draft, fuel-fired furnace having a heat exchanger with an inlet and an outlet includes a vent having an inlet, a burner, and a vented vestibule in fluid communication with the vent. A blower has an inlet in fluid communication with the heat exchanger outlet, and an outlet disposed at the inlet of the vent. The blower outlet has a cross-sectional area smaller than the vent inlet. The vent inlet and blower outlet define a vent inlet opening. A drafthood formed with an inlet is disposed in the vestibule and forms a plenum in fluid communication with the vent inlet opening. A source of combustion products is disposed in the furnace such that combustion products produced thereby are in fluid communication with the drafthood inlet and vent inlet opening. The source of combustion products includes either a standing pilot or electronic ignitor for igniting fuel operably discharged from the burner.

Abstract: A high efficiency fuel-fired induced draft condensing furnace is provided with a horizontal vent termination assembly installed in an exterior wall of a building served by the furnace. The vent termination assembly, constructed entirely from PVC plastic pipe and fittings, includes a combustion gas vent pipe connected to the furnace's draft inducer fan outlet, horizontally extending through an opening in the wall, and having an open discharge end positioned outwardly beyond the wall. A larger diameter combustion air inlet pipe circumscribes the vent pipe within the wall opening and forms around the vent pipe an annular combustion air flow passage that is communicated with the furnace combustion air inlet. A coupling member connected to the outer end of the inlet pipe has a diametrically enlarged end portion positioned on the outside surface of the wall, axially inwardly of the outer vent pipe, and forming an annular inlet to the flow passage between the two pipes.

Abstract: A fuel-fired condensing furnace is provided with a specially designed heat exchanger structure having a metal primary section and a plastic secondary or recuperative section. The primary section is defined by a horizontally spaced series of identically sized, vertically serpentined metal combustor tubes adapted to receive a throughflow of a burning fuel-air mixture discharged from the furnace burner section. Each tube has an essentially straight inlet combustion section sized to permit essentially complete combustion therein of the burning fuel-air mixture received by the tube, and a plurality of vertically spaced horizontal heat transfer sections that are horizontally flattened and narrowed to enhance their combustion heat transfer to supply air being forced upwardly through the furnace housing.

Abstract: A compact heat exchanger for a fuel-fired heating furnace. The heat exchanger has a radiative heat transfer section including at least one firetube for containing flue gases as the air to be heated passes over the firetube and a convective section including a shell-and-tube heat transfer apparatus arranged to receive flue gases from the firetube in the shell region and the air to be heated after it passes over the firetube in the tubes.

Abstract: A heating and air conditioning unit has a fan compartment containing a hammock-type filter. The hammock-type filter rests upon feet elevated above the bottom of the fan compartment so that air may flow into the fan through either the bottom panel of the hammock filter or either of the side panels. The front and back of channels of the bottom pannel are telescoped so that they can be expanded and always be longer than the width of the fan. Sponge rubber is provided at the front and back so that if a larger compartment is used that air leakage at the front and back is prevented by the sponge or foam rubber. The top edges of the side panels rest against the sides of the fan compartment. Foam rubber along these edges prevents noise caused by vibration as well as preventing air leakage.

Abstract: A high efficiency fuel-fired condensing furnace is provided with a compact recuperative heat exchanger structure comprising a metal primary heat exchanger positioned above and operatively connected to the inlet side of a secondary heat exchanger formed from a polyetherimide (PEI) plastic material. The primary heat exchanger is formed from a horizontally spaced series of vertically serpentined metal combustor tubes, and the second heat exchanger if formed from horizontally spaced apart injection molded inlet and outlet collector boxes interconnected by a horizontally spaced series of elongated hollow extruded plate members sealingly secured at their opposite ends to the collector boxes with the side edge-to-side edge widths of the hollow plate members being vertically oriented. The outlet ends of the metal tubes are operatively connected to the plastic inlet collector box.

Abstract: The present invention relates to a unitary heat exchanger for an air conditioner which is capable of minimizing the size, weight, and the power consumption thereof, and improving the thermal efficiency. The unitary heat exchanger comprises an air intake member for introducing the room air, and a combustion furnace for firing a fuel with the air introduced through the air intake member to generate a hot combustion gas. A heat exchanger is disposed in line with the furnace for passing the hot combustion gas from the combustion furnace therethrough and heating fresh room air supplied by a blower. An air exhaust member discharges the hot combustion gas from the heat exchange means.

Abstract: An apparatus for cooking an article is provided including a cooking chamber, a heating means for producing heated gases for introduction into said chamber for convective heating without microwave interference, and a source of microwaves for heating with microwave energy. At least one freely rotating stirring means is positioned in gas and microwave communication with the heating chamber, and is caused to rotate from a flow of the heated gases. The stirring means serves to distribute both microwave energy and the heated gases about the chamber for uniform, simultaneous convection and microwave heating. A pilotless gas source is provided which includes an initiation chamber within a combustion chamber. The initiation chamber is positioned by a microwave opaque material and includes a flame sensor which eliminates the flow of gas in the combustion chamber when no flame is present.

Abstract: Elongated metal devices are coaxially inserted into, and closely received within, inlet end portions of the heat exchanger combustor tubes of a fuel-fired heating appliance, representatively a forced air heating furnace. The inserted devices function to substantially reduce the NO.sub.x content of the combustion gases ultimately discharged from the furnace by intercepting, dispersing, and thermally quenching the burner flames drawn through the combustor tubes by a draft inducer fan portion of the furnace. Each device is formed by a pair of elongated, generally rectangular slotted metal plate members which are longitudinally overlapped and transversely secured to one another in a manner providing the device with a generally cross-shaped cross section along its length. Elongated slots are formed in the four outer side edges of the device for operational sound reduction purposes. An alternate embodiment of the device is formed by welding together two elongated metal members each having an L-shaped cross section.

Abstract: A toxic gas exhaust suppression-type combustion system burns a hydrocarbon-based fuel and comprises, an incomplete combustion section for causing incomplete combustion by supplying the fuel and a small amount of air, a solid component removing section, connected to said incomplete combustion section, for collecting and removing a solid component, such as soot, within an unburned gas generated by said incomplete combustion section, and a complete combustion section for perfectly burning a remaining unburned gas by supplying a sufficient amount of air, the remaining unburned gas being obtained by removing the solid component from the unburned gas generated by said incomplete combustion section by flowing the unburned gas through said solid component removing section.

Abstract: A condensate trap in the exhaust gas conduit of a forced draft water and space heater comprises a housing providing a chamber open at its upper end to the exhaust conduit and having a condensate outlet below the inlet and controlled by a float valve in the chamber.

Abstract: A heat exchange assembly having a primary heat exchange element (20) intercommunicating with secondary heat exchange element (24) both housed in an enclosure (12). Hot combustion products from burner (28) are forced by fan (19) through the primary and secondary heat exchange elements in turn to an exhaust (31) whilst air to be heated is induced by fan (14) through enclosure (12). The flow direction of hot combustion products and their temperature drop along their flow path when considered with the flow direction of air being heated and delivered from outlet (16) of enclosure (12), ensures heat exchange characterized predominantly as counter-current and hence optimally efficient in consideration of the compact dimensions of the enclosure (12).

Abstract: The present improvement is forced air furnaces comprises structure having redisposition of the vestibule panel of a forced air furnace from a location between the flue collector box and the circulating air flow to a location between the inducer motor and the induced draft fan housing. Advantages over prior art structures obtained by such forced air furnace structure having the novel disposition and location of the vestibule panel of the present invention is that the induced draft housing and the flue collector box are then located within the heated and enclosed circulating air flow chamber. One primary advantage of this structure is a significant decrease in noise emitted by the induced draft fan housing, and thus reduction of noise from the forced air furnace as a whole. Moreover, loss of heat from the induced draft housing and the flue collector box are prevented, while more beneficially disposing the inducer motor within the cooler environment of the vestibule area.