Abstract: A heater for burning combustible pelletized fuel. The pelletized fuel is delivered at a controllable rate to a double-walled burn pot in an enclosed combustion chamber. Combustion air is injected into the combustion chamber at a pressure higher than the ambient air pressure surrounding the heater. Combustion air is injected between the walls of the burn pot through ports in the inner wall into the fuel at or slightly below the top of the fuel level. Additional combustion air is injected approximately horizontally across the top of the burn pot through an injection air manifold. Crossfire injection air is injected approximately vertically about the periphery of the burn pot, confining fumes and exhaust air directly above the burn pot. Heated exhaust gasses rise to the top of the combustion chamber and are drawn from the combustion chamber through a heat exchange unit surrounding the combustion chamber. The exhaust gasses are drawn from the combustion chamber by suction created by and extraction air mechanism.

Abstract: A filter support base for use with an upflow forced air furnace is disclosed. A rectangular base defining a return air plenum is adapted for floor mounting support of the furnace and includes a pass-through opening in communication with the intake opening of the furnace plenum. A filter base provides a rectangular enclosure that is secured intervening between the base and the supported furnace. Within the filter box there are elongated channel members extending about the internal perimeter in planar alignment with a filter access opening for support of a received filter element in the return air stream. A cover, hinge supported above the opening, is displaceable for covering the opening during normal furnace operation and for exposing the opening when filter access is desired.

Abstract: An improvement in a woodburning stove of the type including an exhaust flue opening; a combustion chamber for primary combustion, having an access door, a support for wood to be burned and a primary air inlet means for supplying primary air to support primary combustion of the wood to produce flue gases containing combustible particulate material; conduit means for directing the flue gases from the combustion chamber to the flue opening in a preselected path; and, secondary combustion means for burning the particulate material in the flue gases before the flue gases pass through the exhaust flue opening.

Abstract: A filter support base for use with an upflow forced air furnace is disclosed. A rectangular base defining a return air plenum is adapted for floor mounting support of the furnace and includes a pass-through opening in communication with the intake opening of the furnace plenum. A filter base provides a rectangular enclosure that is secured intervening between the base and the supported furnace. Within the filter box there are elongated channel members extending about the internal perimeter in planar alignment with a filter access opening for support of a received filter element in the return air stream. A cover, hinge supported above the opening, is displaceable for covering the opening during normal furnace operation and for exposing the opening when filter access is desired.

Abstract: This invention provides improved gas-fired heater means for supplying heat to a space, such as a room, house, building, vehicle, or the like.

Abstract: According to the present invention there is provided a boiler comprising a firebox, a control device controlling the flow of air into the firebox, a water jacket surrounding at least part of the firebox, a sensor to sense the temperature of the water in or being discharged from the water jacket, the sensor being adapted to control directly or indirectly the control device. The sensor can be a temperature sensitive valve associated with the water jacket to control the position of the control device to thereby govern the flow of air to the firebox. The invention further provides a method of providing space heating and hot water from a boiler unit comprising the operation of a boiler unit.

Abstract: A self-contained, free standing, on-demand, woodburning furnace including a firebox (52), including means to force combustion gases through a manifold (68), a hot air gathering plenum and means to selectively force feed the fire (34, 36, 38, 40, 68) and draw heated air from the furnace (8, 10, 12, 14).

Abstract: This invention is an attachment for installation along a flue duct between a heater and a chimney, including a flue duct section, having a jet tube therein, receiving air from an exterior motor-driven fan, so as to create a vortex and a third stage burner at the jet tube end.

Abstract: A flue gas/combustion air heat exchanger for a furnace. The furnace includes a combustion chamber that burns a mixture of fuel and combustion air to produce heat for a comfort zone. The resulting products of combustion, along with any waste heat not transferred to the zone, pass through a flue duct before venting to atmosphere. Incoming combustion air is discharged across the relatively hot flue duct before it enters the combustion chamber. In passing across the hot flue duct, the incoming air is preheated by waste heat of the combustion products. The heat exchange relation between the incoming combustion air and the combustion products within the flue duct enables the furnace to recover waste heat that would otherwise be lost if the combustion products were free to discharge to atmosphere before giving up a portion of their waste heat to the incoming combustion air.

Abstract: An apparatus for heating water, especially a hot-water boiler. The apparatus has a combustion chamber and two or more heat exchangers that are disposed one above the other. The heat exchanger disposed in the bottom of the apparatus is associated with a condensation chamber. In order to be able to operate this heat exchanger without water, and to be able to raise the efficiency of the apparatus as a whole, the heat exchanger of the condensation chamber is provided with a fresh air inlet and a fresh air outlet. Air is conveyed through this heat exchanger, whereupon it is heated up. This warmed air is supplied to the burner of the apparatus.

Abstract: Fresh air make-up apparatus for a furnace located in an enclosed building comprises an elongated diffuser housing positioned adjacent the furnace, with the housing having an inlet in communication with fresh outside air and a pair of outlets, one being connected to the cold air return of a forced air furnace at a point substantially upstream of the heat exchanger, and the other outlet leading to the room. The outlet leading to the cold air return provides fresh make-up air for the building, while the opening leading to the room provides both a means for diffusing and preheating the fresh air supplied to the cold air return and a means for providing fresh air diffused with warm room air to the combustion in the combustion chamber of the furnace. The apparatus also includes a removable filter for removing contaminants from the fresh air. The apparatus can include a heat exchanger for preheating the fresh air with warm air from the warm air duct of the furnace.

Abstract: A method and apparatus for maintaining the desired level of excess air in a two stage gas furnace system. Low and high pressure switches are placed across the heat exchanger and are successively closed, as the inducer motor accelerates during purging, when the pressure drop reaches the respective theoretically desired low and high firing pressure drop levels. As the switches are closed, the inducer motor speeds are sensed and recorded, with a ratio of the two then being calculated. After firing, the ratio is then directly applied to a desired high firing motor speed to obtain the desired low firing motor speed.

Abstract: Method and apparatus for maintaining excess air control in a gas furnace. A pressure switch is placed across a heat exchanger to indicate when, while accelerating the inducer motor speed during purging operation, the pressure drop reaches a predetermined level. When that occurs, the motor speed is sensed and recorded. When the furnace is subsequently fired, the desired inducer motor speed is obtained by modifying the recorded motor speed on a correction factor derived from empirical data obtained from a gas furnace operating under selective variable conditions.

Abstract: An intake air pathway for a wood-burning stove is provided with a control mechanism which automatically responds both to changes in temperatures for controlling the amount of intake air flowing in the pathway and to pressure due to back puff conditions in the stove for closing the intake pathway with and thereby preventing emissions due to back puff. The point of control of the intake pathway may be placed along different points of the pathway. Control valve and check valve functions may be accomplished with a single control surface (i.e., plate or flap), or alternatively, be segregated into two control surfaces. The control arrangement is disposed such that gravity always acts as a safety feature to close the intake air pathway during an uncontrolled fire (e.g. chimney fire) or physical failure of the control apparatus. A fixed-shield baffle system surrounding a combustor of the stove causes reversals of combustion gasses and a secondary air flow supplied to the combustor.

Abstract: Stove for burning solid fuels, particularly wood. The stove has a pedestal which has a primary air inlet and an ash drawer; an upright rectangular main housing which is divided internally into a fire box section and a section for combustion products; a housing for electrical components on the back of the main housing; and a flue. The partition between the fire box and the top portion has a first passageway with a catalyst therein and a damper-controlled bypass passageway. Primary air is admitted beneath the grate and passes upwardly therethrough. Secondary air is admitted to the fire box near the glass-panelled charging doors for solid fuel. The stove has a catalyst chamber for completing combustion of the incompletely burned gases in the fire box.

Abstract: An improvement in a woodburning stove of the type including an exhaust flue opening; a combustion chamber for primary combustion, having an access door, a support for wood to be burned and a primary air inlet means for supplying primary air to support primary combustion of the wood to produce flue gases containing combustible particulate material; conduit means for directing the flue gases from the combustion chamber to the flue opening in a preselected path; and, secondary combustion means for burning the particulate material in the flue gases before the flue gases pass through the exhaust flue opening.

Abstract: A solid fuel furnace having an oscillating grate plate solid fuel burner therein wherein the grate plates are in a stepped arrangement and every other plate moves together, in an opposite direction from the adjacent plates so that the solid fuel is kept moving down the step grate positively. Additionally, the solid fuel burner is mounted in a furnace housing which is designed to utilize the hot combustion gases to preheat incoming or makeup air for a blower used for supply air flow for heating. Baffles are used to provide a substantially elongated path for the combustion gases to ensure adequate heat exchange in a compact space.

Abstract: Solid fuel heating appliance having high thermal efficiency and low levels of polluting emissions. The heating appliance includes an insulated secondary combustion chamber where a mixture of exhaust gases from the primary combustion chamber and secondary air is burned. A catalytic igniter is provided in the secondary combustion chamber to lower the ignition temperature of the unburned volatile gases from the primary combustion chamber. Regenerative feedback structure is provided in heat exchange relationship with the exhaust from the secondary combustion chamber to preheat the mixture entering the secondary combustion chamber, catalytic igniter, and the regenerative heat transfer assure substantially continuous combustion within the secondary combustion chamber even when conditions in the primary combustion chamber change.

Abstract: A firebox for a wood stove provides primary, secondary, and tertiary supplies of combustion air to the firebox. The primary supply of air enters from the front of the firebox and establishes a combustion flow downwardly to the fire. Smoke containing particulates and gases then rises from the fire to a flue opening through the top of the firebox. The secondary supply of air is added to the flow of smoke as it rises to combust particulates and gases in the smoke. The tertiary supply of air is then added to the flow of smoke in surrounding relationship to the smoke flow as it passes through a restriction opening, further combusting the smoke. The primary, secondary, and tertiary supplies of air enter the firebox through primary, secondary, and tertiary inlet ports, the cross-sectional areas of the ports being in the ratio of 2 to 1 to 1 to regulate the flow of air inward. The secondary and tertiary air supplies are preheated before being added to the combustion flow.

Abstract: An improved solid fuel burning stove arrangement to heat a selected space including a housing defining a combustion chamber, with an access door thereto for providing fuel to the chamber, a tubular combustion air sparger located longitudinally in the bottom of the chamber and having a multiplicity of generally radially directed air flow apertures, an air supply for the sparger to supply combustion air to the combustion chamber, a plenum chamber disposed in heat contact relation with the housing to receive heat generated in the combustion chamber, an air inlet to the plenum chamber and air outlet from the plenum chamber to the space to be heated, an exhaust stack communicating with the combustion chamber, a stack plenum chamber surrounding a portion of the exhaust stack to receive heat from the combustion gases passing therethrough and having an air inlet and a heated air outlet from the exhaust stack plenum chamber and further including first control device to initiate operation of the combustion air supply w

Abstract: A dual stage combustion furnace has primary and secondary combustion chambers. The primary combustion chamber contains a solid fuel, such as wood or coal. The secondary combustion chamber is formed adjacent to and in communication with the primary combustion chamber for containing and igniting volatile combustion gases produced in the primary chamber. A plurality of hollow members, which provide a grate, extend through the primary chamber, and into the secondary chamber. Volatile gases given off in the primary combustion chamber are then ignited and burned in the secondary combustion chamber upon combination with heated air passing through the hollow grate members.

Abstract: The present invention provides a heating device including a combustion chamber for burning a selected fuel where the combustion chamber is at least partially surrounded by air heating plenums through which ambient air is forced. A portion of the air supplied to the plenum chamber is supplied to the combustion chamber to support combustion of the fuel and the device further includes a combustion air flow control device operated by a bi-metallic temperature sensing element located in an outlet of the heated air stream to attenuate flow of combustion air to the combustion chamber in response to change in the temperature of the heated air.

Abstract: A furnace flue gas draft inducer outlet box assembly is provided for connecting an inducer housing to a vent pipe, and comprises a plurality of differently directed openings to allow the vent pipe to be connected thereto in one of a plurality of different orientations, thereby facilitating ease of installation of the furnace. When incorporated with a condensing furnace, the inducer outlet assembly further comprises a condensate collecting system for collecting a return flow of condensate formed in a vent pipe and for delivering the condensate out of the inducer housing to prevent contact with the inducer motor, wheel and the like.

Abstract: A pulse combustion apparatus in which combustion air is brought into heat exchange relationship with the exhaust system of the apparatus for preheating the combustion air prior to entering the combustion chamber. In a preferred embodiment this is achieved by passing the combustion air through a space between an exhaust cushion chamber of the exhaust system and a housing which encloses the chamber.

Abstract: The disclosure is directed to a furnace having an elongate, cylindrical, combustion chamber surrounded by a water jacket. Air is blown into the combustion chamber through a loop-shaped distributor having a front bight and a rear bight and parallel horizontal side members. Axially-oriented jet ports are disposed in said bights which direct jets of air toward each other into the center portion of the combustion chamber and chord-oriented jet ports in the side members which direct jets of air downwardly toward the bottom center of the combustion chamber. Fire-tubes are located in the top portion of the water jacket through which the combustion products flow in heat exchange with the water introduced into the water jacket and second fire-tubes in heat exchange with the outlet water lead the combustion gases to a stack. A special band of scraper-deflectors is provided on at least some of the fire-tubes.

Abstract: A heater is disclosed for burning combustible particulate fuels. The fuels are delivered to an internal retort at a constant rate. They are burned at an open end of the retort with the aid of a primary air supply manifold that surrounds the open end of the retort and directs primary combustion air into the particulates at the open retort end. Secondary combustion air is directed through an annular air supply manifold situated above the open retort end. The hot exhaust gases pass upwardly through a combustion chamber and subsequently downwardly through an exhaust gas plenum to an exhaust gas discharge. Flow of the combustion air and exhaust gases is induced by a vacuum blower mechanism by which a reduced pressure is produced within the combustion chamber to draw air through the primary and secondary air supply manifolds. The exhaust gases drawn off by the vacuum mechanism are pressurized on a discharge side of the vacuum mechanism.

Abstract: Apparatus supporting a catalytic converter for a burner comprising a support including an opening for passage of exhaust gases therethrough, a catalytic converter mounted on the support for movement into and out of an operating position adjacent to the opening to receive the exhaust gases, and means extending from the support for causing the catalytic converter to be moved into and out of the operating position.

Abstract: A solid fuel combustion chamber having fire bars supporting the fuel and two screening walls located above the fire bars, one screening wall overlying the other having an inlet opening larger that and communicating with the outlet of the underlying screening wall.

Abstract: A gas-fired, condensing mode, hot air furnace has an exhaust passage for carrying the products of combustion from a gas burner to an exhaust flue. A heat exchanger is provided in the exhaust passage for extracting heat from the products of combustion. An air passage is provided for carrying a flow of air over the heat exchanger and a blower causes a flow of air through the air passage. The gas burner is enclosed and fires into the heat exchanger. A fresh air duct communicates with the burner enclosure for admitting fresh air thereto. A condenser is provided in the exhaust passage for removing water from the products of combustion, the condenser being exposed to the air passage. A second blower is provided in the exhaust passage for causing fluid flow therein from the fresh air inlet duct through the enclosure and the exhaust passage to the exhaust flue.

Abstract: A control unit for make-up air and combustion air is disclosed for use with a furnace in an air circulating system for a building. A baffle having a combustion air inlet and a make-up air inlet is provided with a weather protective hood and adapted to be mounted on the outside wall of a building. The combustion air inlet is connected through a conduit to a location adjacent the floor of the building on which the furnace is mounted. The baffle includes a restrictor plate including a pair of openings aligned with the combustion air and make-up inlets, respectively, and including a screen extending across the openings. The baffle includes a damper in the make-up air inlet which opens in response to reduced pressure in the furnace return air duct so that the inside pressure tends to be equalized with the outside pressure.

Abstract: The present invention is a vertically loaded wood-burning stove in which the wood stands on end and burns only on the lower end, sliding down into the combustion zone as it is consumed. The wood-burning chamber is air tight with the exception of unobstructed air inlets at the bottom of the chamber. The hot combustion gases pass from the combustion chamber through unobstructed air passageways to a second combustion chamber which is vertically arranged and spaced from the first combustion chamber to form an unobstructed secondary air inlet which provides pre-heated air to the second combustion chamber.

Abstract: A control unit for make-up air and combustion air is disclosed for use with a furnace in an air circulating system for a building. A baffle having a combustion air inlet and a make-up air inlet is provided with a weather protective hood and adapted to be mounted on the outside wall of a building. The combustion air inlet is connected through a conduit to a location adjacent the floor of the building on which the furnace is mounted. The baffle includes a restrictor plate including a pair of openings aligned with the combustion air and make-up air inlets, respectively, and a screen extending across the openings. The baffle includes a damper in the make-up air inlet and a damper in the combustion air inlet. The dampers are mounted on a common shaft so that they move concurrently in response to a pressure differential between the inside and outside.

Abstract: A firebox for a stove is defined by top, bottom, side and end walls and employs a loading door in one of the end walls. A main draft opening associated with an adjustable damper control is provided adjacent the lower portion of the firebox and an auxiliary draft opening associated with an adjustable damper control is provided adjacent the top portion of the firebox. In a preferred arrangement the main and auxiliary draft openings are disposed adjacent one of the end walls. Also, in a preferred arrangement, the auxiliary draft opening is disposed upwardly within at least the upper one-third of the firebox. The particular structure of the stove facilitates good combustion for heating but at the same time provides an efficient shut-down condition that will maintain a small holding fire without causing creosote to build up in the flue. The main draft opening is associated with a movable door arranged to be forced open in the event of pressure being developed in the firebox.

Abstract: Apparatus is disclosed for operating a gas furnace system (100) having an air intake (102) for supplying external air into a sealed chamber (110) for input to a gas burner assembly (118). Exhaust air from within the combustion burning chamber (140) is applied through an exhaust duct (170) directly into an environment (174) which is external to the furnace system (100) but which is still within the environment to be heated. The furnace system (100) also includes a conventional fan limit assembly (142) wherein the typical high limit setting is substantially decreased so that a blower fan (160) is activated at lower than normal temperatures. In addition, the conventional gas furnace burner is replaced with a burner assembly (118) having substantially small burner ports (130).

Abstract: A system for generating, storing and releasing heat comprises a tank surrounding a reservoir for holding a heat transfer fluid, heat releasing means in fluid communication with the reservoir for controllably releasing heat from the fluid to an object or space to be heated, and means for regulating flow of the fluid between the reservoir and the heat releasing means. A heat conductive fire chamber is disposed within and substantially surrounded by the reservoir, the system also comprising an air supply means for carrying combustion air to the fire chamber, and a heat conductive exhaust means for carrying hot exhaust gases through the reservoir. Access passageways are provided for fuel insertion and ash removal. Boiler tubes supporting the fuel as well as collecting heat from the fire chamber communicate with fluid in the reservoir. Shaker bars interspersed between the boiler tubes supporting the fuel may be actuated to agitate and more completely combust the fuel.

Abstract: A noise reducing heat exchanger assembly for a combustion system is disclosed. The heat exchanger assembly includes a plurality of side by side heat exchangers each having a single inlet for an inshot burner. An auxiliary port is located just above each burner inlet. A coupling chamber may be used to interconnect the auxiliary ports to allow acoustical coupling between the heat exchangers and to substantially prevent potential fluid flow between the heat exchangers and the surroundings of the combustion system. This heat exchanger assembly is particularly suitable for use as part of an induced draft combustion furnace.

Abstract: A burning method and apparatus, using solid type fuel, comprising a combustion chamber in combination with a heat-extractor labyrinth chamber through which an artificial draft is generated mechanically. The artificial draft can be generated by intake and exhaust fans and/or blowers operating at accurately controlled speeds.In a specific stove-type embodiment, the draft-flow within the combustion chamber is utilized by a reversal of its flow pattern for either conventional up-draft burning, or preferably, for down-draft burning, with the gases exiting through the heat extractor compartment at close to ambient temperature and a short horizontal flue into the atmosphere. In this embodiment, the intake fan also serves to distribute usable heat from the surfaces of the combination and heat extractor compartments.

Abstract: A fireplace having one or more conduits for directing outside combustion air into the firebox with a movable member adjacent a conduit outlet for normally closing said conduit and having either open or closed positions dependent upon the existence of a pressure difference across said member. A pressure difference caused by a fire in the firebox results in a higher pressure on the side of the member opposite the firebox to cause the member to move to open position. Operating structure is provided for positively closing the member and with the operating structure being operable from the front of the fireplace.

Abstract: A wood burning stove having improved air flow characteristics for effective combustion and purging of gaseous combustion by-products. A primary air inlet is provided below the loading door of the stove for feeding air to the firebox proper for combustion. A plurality of opposing supplementary air inlets are provided in opposite sides of the stove, at least two of the supplementary inlets being on the level of the primary air inlet, for introducing air into the firebox supplemental to the air flow through the primary inlet.

Abstract: A solid fuel furnace which includes a housing enclosing a firebox and a heat exchanger chamber. An open grate in the firebox supports solid fuel thereon. Combustion air is admitted to the area below the grate and is preheated and passes upwardly through the grate and fuel and mixes with volatile gases released from the fuel. The air/gas mixture is drawn downwardly through the fuel and exits the firebox through an inlet to an insulated burn-out chamber which is behind the firebox. A metal screen covers the inlet and serves to ignite the air/gas mixture. Hot flue gases exit the burn-out chamber to the heat exchanger chamber.

Abstract: The assembly is adapted for replaceable and operative installation within the opening of a standard fireplace. It comprises a combustion chamber and conduitry to accomodate ambient air entry into the chamber in a number of patterns and includes an arrangement for air preheating. Air is also heated by contact with the outside of the chamber and is expelled with mechanical assistance. Exhaust smoke is expelled through a baffle system in order to extract therefrom all useful heat.

Abstract: A gas furnace is described which is of conventional design except for the means by which combustion air is supplied to the burner assembly. The gas furnace includes a cabinet having a burner assembly, heat exchanger and flue provided therein. The flue is in communication with a chimney extending upwardly from the building. An enclosure extends around the chimney and is spaced therefrom to define an air passageway. The upper end of the air passageway is in communication with the atmosphere outside of the building. Duct work connects the lower end of the air passageway with the combustion air opening formed therein so that combustion air for the burner assembly will be drawn from the outside atmosphere downwardly through the air passageway rather than from the interior of the building. As the air passes downwardly through the air passageway, the air is heated by the chimney.

Abstract: An outdoor furnace including a conditioned air chamber surrounding a fire box and having an air inlet and outlet connected to the space to be heated within the building. The furnace is characterized by a pre-heat chamber for the combustion inlet air as well as deflectors and baffles for maximizing contact of conditioned air flow over the fire box for maximizing the efficiency of the furnace. The furnace may also include an after-burner chamber and a damper for varying the degree of combustion within the after-burner chamber. The furnace also preferably includes an exhaust damper having a thermal control for exhausting excessively heated air from the conditioned chamber.

Abstract: A control regulates the rate of flow of combustion air flowing into an airtight stove or furnace10 containing a fire. A control element 15 or 45 is arranged in communication with the air inflow stream and moves in response to the velocity of the flowing air. The control element 15 or 45 moves to constrict the area of the inflow stream as air velocity increases and to open the area of the inflow stream as air velocity diminishes. Springs 25 and 26 or 60-62 bias the control element toward a maximum opening, and the spring bias is non-linear to provide increasing resistance to movement as the control element approaches a closed position. The spring bias system is preferably adjustable to vary the air inflow rate that is otherwise kept steady by the control element.

Abstract: A stove, particularly adapted for burning wood, includes a system for delivery of air to the combustion chamber which features a plurality of elongated headers arranged to deliver air relatively uniformly along the entire length of the combustion chamber.

Abstract: A combination furnace including a solid fuel burning section and an electrically powered heating section. The two sections are disposed within an upright, insulated casing. A heat exchanger is provided above a fire box which constitutes the fuel-burning section. Dampers control the flow of combustion air to the fire box and the heat exchanger.

Abstract: A heat exchanger furnace includes a firebox, a heat exchanger housing in communication with the firebox for receiving combustion gases therefrom, and a plenum housing surrounding the heat exchanger housing so as to define a plenum chamber therebetween. A plurality of baffles are supported in vertically spaced apart relation within the heat exchanger housing, which baffles include peripheral edges disposed in clearance relation from the housing sidewalls whereby hot combustion gases rising within the heat exchanger housing are directed outwardly adjacent the heat exchanger sidewall for increased heat transfer to the plenum chamber. Exhaust tubes at the top of the heat exchanger housing may be directed through the plenum chamber for providing additional heat transfer surfaces therein. The firebox may have a frusto conical shaped sidewall whereby the combustion surface area may be adjusted with the level of fuel in the firebox.

Abstract: A housing is provided defining a closed lower combustion chamber and a closed upper afterburn chamber disposed immediately above the combustion chamber with one marginal portion of the combustion chamber projecting horizontally outwardly beyond the corresponding marginal portion of the afterburn chamber. A combined flue gas and bypass chamber is disposed above the one marginal portion of the combustion chamber and is horizontally registered with the afterburn chamber. Partition structure divides the combined flue gas and bypass chamber into central and remote end portions spaced along the aforementioned one marginal portion and a pair of first ports communicate the remote portions with adjacent underlying upper portions of the combustion chamber, a pair of second ports communicate the remote portions with adjacent portions of the afterburn chamber and third port structure communicates the central portion of the afterburn chamber with the central portion of the combined chamber.

Abstract: Improved flue structure for domestic heating equipment such as a gas fired hot water heater. In conventional gas fired water heaters, the heater is directly connected to a chimney or the like by a single flue pipe and this results in a wasteful loss of heat and inefficient use of fuel. The invention provides a multiple, interconnected flue pipe arrangement whereby a substantial portion of the heat produced by the gas burner is trapped in the flue structure keeping it in the system longer and thereby materially cutting down on the heat loss. In one embodiment of the invention, a flue pipe from the heater is connected to the upper end of a second flue pipe that is closed at its top and a third flue pipe, concentrically mounted in the second flue pipe, conducts the heater flue gases to the chimney. Due to the arrangement of these pipes as will be described in detail hereinafter, heat is trapped at the upper end of the second flue pipe resulting in a substantial increase in efficiency.

Abstract: A fireplace or stove apparatus for efficiently providing heat to a structure without loss of interior air to the flue draft. A blower forces outside air through a conduit located in the exhaust flue into a grate located in a fireplace or stove. The fuel loading opening of the fireplace or stove is made substantially air-tightly sealed. An air opening in the grate provides air to be consumed by the fire. A second air opening in the grate is fluidly connected by means of a conduit to the structure to be heated.