Abstract: A method and apparatus for increasing the circulating airflow of induced-draft, gas-fired multi-stage furnaces without creating conditions that result in cold spot corrosion therein. Control circuitry is provided to selectably increase the circulating airflow of the furnace during low stage operation. The control circuitry is arranged so that increases in the magnitude of the circulating airflow of the furnace are accompanied by predetermined increases in the magnitude of the combustion airflow of the furnace. The magnitudes of the circulating and combustion airflows are so related to one another that the temperature at the output of the heat exchanger is maintained at a value which is approximately constant, and which is high enough to assure that water cannot condense thereon. The control circuitry may include a relay or relay-like device that is connected to prevent the high stage solenoid of the gas valve from becoming actuated during low stage operation.

Abstract: A modulating furnace includes a first air flow path which directs supply air to one or more combustion burners and through a heat exchanger, and a second air flow path which directs supply air around the one or more burners and heat exchanger. When the firing rate of the burners is lowered, the amount of air to the burners is reduced by diverting a greater fraction of the supply air to the second air flow path. When the firing rate of the burners is raised, less supply air is diverted resulting in greater flow to the burners. The duct furnace achieves ideal combustion at high and low firing rates by maintaining an ideal balance between firing rates and air supplied to the burners.

Abstract: A fuel/air mixture control for an induction heater having a tube-type burner includes a side-venting fuel nozzle for introducing fuel into an induction air stream entering the burner. A multi-speed blower draws combustion air into the burner and an air flow constrictor disposed proximate the fuel nozzle increases the velocity of the induction air stream proximate the fuel nozzle, increasing the volume of fuel introduced into the burner conduit. The fuel/air mixture depends upon the speed of the blower, which can be thermostatically controlled to increase speed upon sensing higher temperature combustion products, thereby maintaining a steady mass air flow and air/fuel mixture.

Abstract: A combustion and heating chamber into which a fluid is pumped under pressure is provided. A burner is positioned in the combustion and heating chamber to provide a heat load to the pressurized fluid in the chamber. As the fluid is heated its internal pressure is greatly raised providing a force for driving the heated air through a spiral conduit that encircles the combustion and heating chamber. An insulated outer wall is fitted around the spiral conduit and in contact with it. The individual wraps of the spiral conduit do not lay side by side, but are spaced apart. Relatively cool process air is drawn into the spaces between the separate wraps of the spiral conduit, which is thereby formed as a second spiral space intertwined with the spiral conduit between the combustion and heating chamber wall and the outer wall. The process fluid is therefore in contact with the walls of the spiral conduit.

Abstract: In an evaporation burner with a combustion chamber (1) for a heater or the like with a peripheral boundary wall (29), a front boundary wall (6) and an air-supply nozzle (8) projecting coaxially into the combustion chamber (1) with radial air outlets (9) through the nozzle wall, a guiding device (32) for a whirling air supply is fitted at or upstream of the air supply nozzle (8) of the combustion chamber (1), in which said air supply nozzle has a diaphragm (10) for axial back-flow (R) of the exhaust gas or the air at the center of turbulence of the whirling air supply (L). In an axial extension of the combustion chamber may be fitted a coaxial flame pipe (20), which together with the peripheral boundary wall (2), may constitute a one-piece (deep-drawn) sheet-metal component and the rest of the combustion chamber may be a cast component.

Abstract: A compact gas combustion furnace includes a substantially rectangular casing having an interior defined by a plurality of compartments. A draft inducer is mounted above the heat exchanger compartment to allow a multipass heat exchanger to be used while allowing the furnace to be fitted within a mobile home closet. A transition box couples the horizontally disposed inlet of the inducer and the vertically disposed outlet side of the heat exchangers. In a preferable arrangement, the furnace includes a burner assembly utilizing a plurality of burners, each having an arcuate shape in relation to a corresponding plurality of heat exchangers, and thereby occupying a minimum of space without loss of efficiency.

Abstract: A new variable burner orifice furnace manifold for reducing the amount of heating fuel used without reducing the heating ability of the furnace. The inventive device includes a manifold pipe with a plurality of spaced apart gas exit openings between its open supply end and its closed end. The gas exit openings are inserted into the burner assembly of a furnace and the supply end is attached to an external heating fuel supply. A valve permitting selective opening and closing is included on the manifold pipe. The valve is positioned on the manifold pipe so that no more than half the total number of gas exit openings are positioned between the valve and the manifold pipe closed end. When the valve is closed, gas flow through the gas exit openings between the valve and the closed end is shut off while gas flow through the gas exit openings between the valve and the open supply end is unaffected.

Abstract: An improved high-efficiency furnace for use with manufactured housing has a modular heat exchanger assembly having a drum and a plurality of serpentine shaped tubes. A burner extends at least partially into the drum portion of the heat exchanger which acts as a combustion chamber. Hot combustion gases flow upwardly within the drum and enter the tubes heating the drum and tubes. Room air is drawn into the furnace by a circulating blower and blown against the plurality of tubes. The room air is then directed to flow around the drum portion of the heat exchanger where it is further heated before being discharged into the space being heated. The burner includes an inwardly tilted target plate having a plurality of fingers for facilitating the formation of a stable ball of flame within the drum.

Abstract: A furnace having improved heat exchanger, which is particularly suitable for use in a positive pressure, direct-vented hot air furnace. The heat exchanger has a split housing construction allowing the heat exchanger to be partible into halves. Parting the heat exchanger housing of the present invention permits access to the ceramic combustion chamber disposed therein, facilitating periodic repair and replacement. The partible portions of the present heat exchanger housing are connectable using one of several available connection means, including bolted mating flanges, encircling clamps, and twisting quick-locking means. The connection between the partible portions is gasketed to provide a positive pressure seal of the connection, impeding leakage of pressurized combustion gases from within the heat exchanger to the occupied air.

Abstract: A heater for heating a stream of air has a burner assembly to heat the stream as it flows along a flow path and a primary heat assembly positioned in the flow path and coupled to the burner assembly for conducting gaseous combustion products. The primary heat exchange assembly has an array of U-shaped heat exchange tubes for conducting hot combustion products generated by the burner assembly to an array of second U-shaped heat exchange tubes for combustion products discharged from the first heat exchange tubes, the second tube having a smaller diameter than the first and being positioned in the space defined by the array of first U-shaped heat exchange tubes. Combustion products leaving the primary heat exchange assembly are passed through a secondary heat exchange assembly before being exhausted.

Abstract: A method and apparatus for reducing emissions in combustion products. Fuel and primary oxidant are introduced into a burner tube and discharged as a fuel/oxidant mixture, preferably fuel-rich, into a primary combustion chamber. The combustion flame entrains, through a peripheral gap between the burner tube and a wall of a first housing, a first portion of secondary oxidant in the primary combustion chamber. The combustion flame is then directed, preferably through a swaged orifice, into a secondary combustion chamber. Within the secondary combustion chamber, the combustion flame entrains a second portion of secondary oxidant and then combustion products are discharged through an exhaust tube.

Abstract: A vaporizing combustion chamber for a heater running on liquid fuel, in particular a vehicle heater, in which inter alia two pipes disposed concentrically one inside the other form therebetween an annular chamber which is closed at a first end. At the second end, the annular chamber is open and leads into a flame diaphragm which projects radially inwards from the outer pipe and is located at a spacing in front of the inner pipe. At both its ends the inner pipe is substantially open and the opening at the second end is contracted by a concentric baffle edge of a baffle plate. In order to improve the emission values of the combustion chamber exhaust gas and reduce combustion noises both when the combustion chamber is disposed horizontally and when it is disposed vertically, the opening in the flame diaphragm is eccentric to the opening, in the inner pipe, formed by the baffle edge of the baffle plate.

Abstract: An indirect-fired climate control apparatus for modifying certain aspects or properties of air flowing through a controlled environment, with the apparatus employing a rotary air-energy exchange device with means for bilaterally introducing and extracting energy from primary and secondary air flows. The apparatus includes a feature for recycling portions of the air flow on the primary side so as to more efficiently utilize the energy resource, and deliver this energy to the secondary side. The apparatus is suited for treating air flow with thermal energy for modifying its temperature, as well as energy for controlling the moisture content of the air flow on the secondary side.

Abstract: In a cross flow type burner apparatus, a burner is provided to which a gaseous fuel and air are supplied by a blower. An air reduction member is provided to reduce an amount of air supplied to specified flame holes of the burner wherein the reduced amount of air is less than the amount of air supplied to the other flame holes. A temperature sensor is provided to detect the burning condition of flames built up on the specified flame holes. A safety member is activated depending on an output generated from the temperature sensor.

Abstract: An apparatus for detecting a head wind in a gas boiler and method is disclosed which is capable of the magnitude of variation of voltage corresponding to the R.P.M. of an exhaust fan and the combustion state of flame. A microcomputer in the gas boiler detects the R.P.M of exhaust fan and voltage applied to the exhaust fan when the R.P.M exceeds a normal limit. The detected voltage is compared with a reference voltage. If the compared result exceeds a predetermined value, to sense the combustion state of flame an infrared rays sensor is used. When the head wind is introduced into an exhaust conduit, the red wavelength is sensed at flame due to incomplete combustion. Accordingly, in case that the magnitude of variation of voltage exceeds a predetermined value and the red wavelength is sensed, microcomputer can detect the head wind.

Abstract: A furnace control apparatus is described wherein a flow of gas into a burner assembly is directly dependent on an indicia of burner combustion air airflow, such as heat exchanger pressure drop. According to one embodiment of the invention, a first communication fluid line is interposed between a gas valve regulator and a heat exchanger at a first point, and a second communication fluid line is interposed between a gas valve regulator a heat exchanger at a second point. The main valve of the gas valve is responsive to the pressure differential between the first and second points so that a flow of gas into a furnace burner assembly is commensurate with a present flow level of combustion air.

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 heating apparatus for delivering heated air to an enclosure comprising a casing with at least two compartments separated by a panel. A burner with an arcuate profile is located within a first compartment of the casing for burning a combustible fuel-air mixture delivered thereto and producing products of combustion. A heat exchanger is located within a second compartment of the casing and has an opposed inlet and outlet. The inlet is in fluid communication with the burner through an aperture in the panel. The heat exchanger receives the products of combustion. A blower is located within the casing for directing a flow of air across the heat exchanger into the enclosure. Through the heat exchanger heat is transferred from the products of combustion to the air. An exhaust system is in fluid communication with the outlet and includes a vent for exhausting the products of combustion from the casing. The vent is contained within the casing.

Abstract: A heat exchanger manifold (44) is provided which includes a plurality of manifold inlet openings (58) including sealant means such as grommet means (62) which receive the tube outlets (40c) of the condensing section (34) of a heat exchanger (28). The heat exchanger manifold (44) is made of a corrosion-resistant material such as a polymer such as one sold under the trademark LEXAN.TM. and the grommets (62) are preferably made of a resilient, corrosionresistant polymer such as rubber, e.g., a nitrile rubber. The condensing tubes (38a, 38b, 38c) are slanted to facilitate drainage of the condensate into the heat exchanger manifold (44) and a flue gas outlet (64) and a condensate drain (49) are provided to discharge, respectively, flue gas and condensate from the heat exchanger manifold (44). The condensing tubes (38a, 38b, 38c) are connected to the primary heating section (30) of the heat exchanger (28) through swaged joints (37).

Abstract: A furnace is adapted for operation in downflow, left horizontal flow and right horizontal flow positions. The furnace includes plural burners, a two-stage heat exchanger, a header box at the heat exchanger outlet for collecting products of combustion from the heat exchanger, and an inducer for inducing a flow of products of combustion through the heat exchanger. A condensate drain and trap are also provided for draining condensation from the header box and from an exhaust vent through which products of combustion are exhausted from the furnace. In accordance with one feature of the invention, a manifold is located inside the header box to divide the header box into first and second chambers. A pressure sensor senses differential fluid pressure between the first and second chambers for detecting a blocked condensate drain condition.

Abstract: A fuel-fired air heating furnace is provided with NOx reduction apparatus associated with a plurality of combustor tubes forming a portion of the furnace heat exchanger section. Inshot-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 NOx reduction members formed from a metal rod material, and a mounting plate having a row of spaced apart pairs of mounting holes therein. Each NOx reduction member has an elongated, generally U-shaped configuration, with a closed inner end, an open outer end, and a spaced pair of corrugated leg portions extending between such inner and outer ends.

Abstract: A flashback resistant burner for lean fuel/air mixtures includes apparatus for mixing a primary fuel and combustion air to form a noncombustible fuel/air mixture. Means are provided for accelerating the noncombustible fuel/air mixture to a velocity higher than the flame speed of a combustible mixture of the primary fuel and air. Means are further provided for mixing a secondary fuel with the accelerated noncombustible fuel/air mixture to form a combustible fuel/air mixture that has an equivalence ratio less than 1. Means are then provided for burning the combustible fuel/air mixture.

Abstract: A condensate trap assembly. The assembly comprises a housing having first and second condensate inlets where the first condensate inlet is sized to pass more condensate than the second condensate inlet. The housing has an ambient air inlet providing access to an ambient air chamber within the housing, a first condensate chamber open to the first condensate inlet, and a second condensate chamber open to the second condensate inlet. The first condensate chamber, the second condensate chamber, and the ambient air chamber are open to each other and the first condensate chamber includes airflow restrictors to retard the volume of airflow through the first chamber.

Abstract: A process and apparatus for combustion of fuel which results in reduction of nitrogen oxides and carbon monoxides emissions. Fuel and primary air are preferably premixed and introduced into a combustion chamber. Secondary air is introduced through a plurality of secondary air ports which are positioned about a venturi nozzle or flame holder disk mounted with respect to a combustion chamber wall. The secondary air flowing through the secondary air ports forms relatively high velocity and momentum secondary air jets that promote rapid mixing of the fuel and primary air mixture into the secondary air flow, such that a combustion flame is established at a periphery of the secondary air jets.

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 metal mesh tubes having diameters substantially less than the internal diameters of the combustion tubes. Each metal mesh tube is coaxially anchored to and telescopingly over the outlet end of one of the burners and extends therefrom coaxially into the associated combustion tube.

Abstract: A high efficiency furnace having a heat exchanger and an inducer fan housing attached to the flue gases exit of the heat exchanger to draw flue gases out of the exchanger and force the gases out of the furnace under pressure through a venting system. A condensate return channel is provided for directing condensate developed in the vent system back into the inducer housing where it its removed from the furnace by a drain.

Abstract: A baffle is located in a recessed location relative to the inlet of a heat exchanger tube and facing the burner. The baffle is made of high temperature ceramic foam and has a plurality of flutes which define the flow path. In passing through the baffle, the velocity of the flame pattern is increased which reduces the noise level. The baffle also reduces NO.sub.x as a result of heat transfer to the baffle.

Abstract: A multi-poise furnace that is capable of operating in either a vertical or horizontal orientation and having a primary heat exchanger coupled to a condensing heat exchanger, apparatus for collecting and draining condensate leaving the condensing heat exchanger.

Abstract: A heat exchanger assembly comprises a partition or mounting plate with an aperture therethrough and a heat exchanger wall with an opening therethrough where the plate and wall are assembled together with the plate aperture and wall opening adjoined and sealed by a sponge pad in accordance with the method of the invention.

Abstract: A high efficiency hot air furnace transfers substantially all of the combustion heat of a clean fuel gas fire to a stream of cool recirculating air by two heat exchangers both of which are mounted in a common plenum through which cool air is recirculated by means of a blower. It differs from the conventional high efficiency furnace in that the secondary heat exchanger is a porous movable heat sink which is alternately exposed to a stream of hot combustion gas and a part of the cool air stream from the recirculating air blower.

Abstract: A compact, non-polluting, extremely energy-efficient, through-the-wall vented forced hot air heater, which humidifies and cleans said hot air without any additional equipment or water supply, comprises a rotating cylindrical heat and moisture transport/storage element which has many substantially identical axially parallel flow passages and very large transfer surface per mass, a means for controllably transferring the heat and the moisture from the combustion products to said rotating element and then to said hot air stream counter-currently, and a means for preventing formation of air pollutants.

Abstract: A pocket heat exchanger comprises an elongated combustion chamber that defines a plane passing through the combustion chamber longitudinal axis. A two-pass, three-pass, or four-pass duct system is arranged symmetrically about the plane to conduct hot products of combustion produced in the combustion chamber in parallel paths to a flue. The pocket heat exchanger is installable as a modular unit into the pocket of a recirculatory fluid system. The symmetrical design of the pocket heat exchanger assures that a stream of recirculating gas flowing past the pocket heat exchanger is heated to have a uniform temperature across its cross section. A shroud partially surrounding the combustion chamber and the duct system aids in directing the recirculating gas to thoroughly scrub the combustion chamber for maximum heat transfer to and temperature uniformity of the stream of gas. The flue for the products of combustion may pass through the stream of recirculating gas, or it may pass outside the stream of the gas.

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: Air heater comprising a gas burner and heat exchange means including at least one heat-exchange wall which separates a first passage for flow of air to be heated from a second passage for flow of the flue gases produced by the burner, the air to be heated being made to flow by blower means through the first passage, the hot flue gases flowing in counter current through the second passage, wherein the burner is of the radiation type, and the heat-exchange wall comprises a convective-exchange part and an absorption part for absorbing the radiation from the burner, the flue gases heating the air by convection mainly in the region of the convective-exchange part, the radiation from the burner being mainly emitted towards the absorption part, the air flowing over this absorption part after it has flowed over the convective-exchange part.

Abstract: A premixed gas burner has a hollow body including a closed end and an entry end into which a combustible gas and air mixture may flow. The body has a multiplicity of apertures through which the mixture may pass from the hollow interior. A burner portal deck is positioned in superposed relationship over the apertures for permitting the gas air mixture to form a controlled flame. A porous woven fabric formed from ceramic fiber having high thermal insulation properties is located above the deck and separates the deck from the flame front formed when the mixture is ignited. The fabric insulates the deck from excessive temperatures, prevents flash back, allows use of conventional stainless steel for the deck and body components and makes possible the manufacture of long burner sections. A long burner section has a number of decks in side-by-side relationship with an insulating fabric mat over the decks for not only providing insulation, but also forms a gasket between the adjacent decks.

Abstract: A self-powered forced or induced draft water heater is provided including a tank adapted for storing hot water, a sealed combustion chamber, a powered burner, a thermoelectric module, and a through-chamber heat sink having a base portion and a pin portion. The combustion chamber has a common wall with the tank at a lower zone of the tank. The powered natural gas burner has a blower which delivers air to the burner through an inlet duct and forces combustion products out a flue. The thermoelectric module generates operating power for the burner blower. The thermoelectric module has a hot side in thermal communication with a combustion zone of the burner and a cold side attached to the heat sink base portion. The pin portion of the heat sink is conically shaped and extends through an opening in the common wall to the interior of the tank. The base portion of the heat sink is removably attached to the common wall and is provided with an o-ring or other means to seal the wall opening.

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: The invention provides in one broad aspect an improved process fluid preheater system for raising the temperature of a process fluid with a hot furnace gas, having a combustion furnace in communication with a shell and tube heat exchanger, wherein the furnace operably produce the hot furnace gas and comprises air inlet means, fossil fuel combustion means and hot furnace gas exit means; and the heat exchanger comprises an exchanger shell, a first end radial tube sheet and a second end radial tube sheet, which define a shell space; a plurality of longitudinal tubes retained by the first and second end tube sheets within the shell and comprising heat exchange means; hot furnace gas inlet means; cooled furnace gas outlet means; process gas inlet means; and heated process fluid outlet means; the improvement comprising the plurality of tubes further comprises the hot furnace gas inlet means and the cooled furnace gas outlet means; the hot furnace gas exit means in communication with the plurality of tubes furnace g

Abstract: A methods and apparatus for exhausting flue products and removing condensate from a combustion of air/gas mixtures provide a condensate collecting pan for flue products. That pan is provided with an inlet for flue products and condensate, and with an outlet for flue products spaced from that inlet. That inlet is provided with a larger cross-section for flue product and condensate flow than the outlet. A space is provided in the pan for a flow of flue products from the inlet at a substantially even velocity across the larger cross-section of the inlet to the smaller cross-section outlet. Condensate collecting in that space is removed from the pan.

Abstract: A burner for burning a combustible gas comprising fuel gas and air that has been mixed before being supplied to the burner. The burner has a flame holder concavely recessed into a flame outlet. The concave configuration of the flame holder focuses the individual flames on the combustion surface toward a central location where the individual flames interact with and reinforce one another in a direction axial to the burner. Thus very little heat is transmitted directly from the burner in a direction normal to the burner axis. This characteristic of the burner allows it to be used to fire a flue type heat exchangers where the walls of the heat exchanger are very close to the burner without excessive temperatures being produced in the heat exchanger walls adjacent the burner.

Abstract: A heat exchanger comprises a clam shell having a first passage, a second passage and a third passage connected sequentially in a plane. A hot collector box made from metal, for example, aluminized steel, in connected to the third passage. A secondary heat exchanger coil is operatively connected to the hot collector box. A second collector box or cold collector box made from plastic is connected to the outlet of the secondary heat exchanger coil. Condensate from the flue and condensate from the cold collector box may be discharged in a common line from the furnace. The clam shell is constructed and arranged to remove about 90%-95% of the energy from the flue products flowing therethrough. The heat exchanger is disposed in a passage between the inlet and the outlet in the housing of a furnace. Air is forced over the heat exchanger, which is disposed in the passage, by a blower in the housing.

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 two-stage induced draft furnace is operated at either high heat or low heat with the gas valve switched to high-fire or low-fire. High-fire and low-fire combustion pressure switches sense the collector box flue gas pressure and actuate respective solenoids of the gas valve. Under some conditions the inducer can produce sufficient negative pressure at low fire to prove the high fire pressure switch and cycle the burners on high fire. To prevent this, relay contacts are interposed between the high fire pressure switch and the gas valve solenoid to deny thermostat power to the high-fire solenoid whenever there is a call for low heat.

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 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 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: 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: A fuel-fired, forced air draft induced heating furnace is provided with NO.sub.x 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 NO.sub.x reduction apparatus includes a plurality of metal mesh tubes having diameters substantially less than the internal diameters of the combustion tubes. The mesh tubes are coaxially supported within the combustor tubes, adjacent their inlet ends, by elongated support members longitudinally passing through the mesh tubes and having first ends anchored to the combustor tube inlet ends, and second ends slidably resting on internal side surface portions of the combustor tubes.

Abstract: A burner for burning a combustible gas comprising fuel gas and air that has been mixed before being supplied to the burner. The burner has a flame holder .[.concavely.]. .Iadd.axially and radially .Iaddend.recessed into a flame outlet. The .[.concave.]. configuration of the flame holder focuses the individual flames on the combustion surface toward a central location where the individual flames interact with and reinforce one another in a direction axial to the burner. Thus very little heat is transmitted directly from the burner in a direction normal to the burner axis. This characteristic of the burner allows it to be used to fire a flue type heat exchangers where the walls of the heat exchanger are very close to the burner without excessive temperatures being produced in the heat exchanger walls adjacent the burner.