Abstract: A hot air heating system utilizing the otherwise wasted heat and water vapor in the gases of combustion to pre-heat air supplied to the combustion unit. The hot combustion gases discharged from the combustion unit are mechanically induced by a blower to pass through an auxiliary heat exchanger in countercurrent flow to the air being supplied to the combustion unit, thereby preheating the return air and cooling the combustion gases. The products of combustion include a considerable quantity of water vapor. Cooling the combustion gases results in condensation of the water vapor, which is then collected and can be utilized to humidify the room air. Condensation of the vapors releases their latent heat of vaporization adding considerably to the heat recovery of the system.

Abstract: This invention relates to a method and apparatus for the extraction of the heat from the flue exhaust of a fuel burn in a furnace, stove or fireplace. The Heat Exchanger Flue can be adjusted vertically and horizonally in length to obtain a high efficiency in the extraction of the heat from said flue exhaust. The design is for the flue to have self cleaning features of soot and fly ash with storage and clean out areas, thus working well when coal is used for fuel. The heat can be extracted from said flue exhaust by air circulation or by water circulation. The design is flexable in the arrangements of the flue, thus allowing installation indoors or outdoors, or the combination of both.

Abstract: Wind guard device for the purpose of sustaining a gentle flow of gas in a gas passageway (6, 8, 11) between a building and the atmosphere surrounding the building and of reducing the wind effect of the atmosphere on the flow of gas, in conjuction with which a heat recovery arrangement (12) for the exchange of heat between the flow of gas and a heat absorbing medium is arranged in the gas passageway. The heat recovery arrangement is provided with a number of birstle-like projections (13) which form between them a number of gas passageways of irregular curved form. Said projections (13) may be heat-conducting and may be connected in a thermally conductive fashion to the heat recovery arrangement so as to increase the thermal absorption capacity of the latter. The heat recovery arrangement may be provided inside the gas passageway in the form of an outwardly inclined jacket, so that the gas which has been cooled by the heat exchange process can fall downwards into the aforementioned area of the gas passageway.

Abstract: A safety device for monitoring the condition of the condensate outlet conduit in a high efficiency furnace is provided which comprises a float member positioned in a condensate trap arranged to float on the condensate and to rise in response to a rising level of condensate in the trap to block the gas vent inlet. A pressure sensing device is utilized to sense the back pressure in the vent and when the float blocks the vent inlet, the back pressure increased and the sensing device will then operate to terminate operation of the furnace.

Abstract: An energy efficient system for controlling the environment in a greenhouse. The system includes an infrared heater, having a burner, a heat disbursement means and an exhaust means, and a layer of reflective and insulative material selectively deployable below the roof and inside the walls of the greenhouse to retain heat within the greenhouse, to prevent excess heat from the sun from entering the greenhouse and to reflect light into the greenhouse from the sun. The system also includes an air-to-water heat exchanger, connected at the exhaust end of the heater, that transfers heat from the heater's exhaust to water used in the greenhouse. The heated water is stored in an underground tank. A series of connected pipes, in communication with the tank, are set into the floor of the greenhouse to circulate the water through the floor to remove excess heat from the water.

Abstract: A heating system designed to extract more than the usual amount of heat from a given amount of fuel by controlling the route of smoke from a firebox through a smoke duct over a tortuous path and exposing the walls of the smoke duct to ambient air, thereby increasing the efficiency of the heating system.

Abstract: An air heating and ventilation system particularly suitable for well-insulated and draught-proof dwellings or buildings, there being provided a supply duct for fresh external air, connected to a main fan, a combustion chamber with an exhaust duct for the flue gases, an air heater disposed in the combustion chamber, a main distribution duct, feed ducts with controllable terminals for the rooms, a dirty air discharge duct provided with a fan, and a heat exchanger disposed between the supply duct for the outside air and the exhaust duct for the flue gases. The dirty air discharge duct is connected to the combustion chamber, so that dirty air at least in part acts as air for combustion and the remaining part is discharged together with the flue gases via the heat exchanger, the latter being adapted for transmitting the resulting condensate to the incoming external air.

Abstract: An apparatus having a heating chamber, (combustion chamber) a heat storing means and heat transferring means of the kind used in households, commercial furnaces, heaters, boilers, etc., having a heating chamber which is spherically arranged; with ports for receiving fuels and a valve for regulating the internal pressure and temperature, allowing for excessive heat to be exhausted into a secondary heat recovery manifold. The spherical heating chamber allows the heat to radiate uniformly. Said heat is stored by mantle material. Said mantle being entirely surrounded by a crust layer and insulating means and an outside protective covering. The apparatus also having means for transferring the stored heat for heating purposes as is generally in common use.

Abstract: A device for evacuating into the ambient air combustion products from a condensation boiler, in which at least one downstream section of the conduit for evacuating the combustion products is coaxial to the conduit for admission of the combustion air necessary for the burner. Means are provided for returning to the outside a fraction of the air collected in said admission conduit. The downstream section of the conduit for evacuating the combustion products, the coaxial section of the admission conduit and the means for returning to the outside a fraction of the collected air define a first heat exchanger. Means also are provided for diluting the combustion product with the fraction of collected air, the dilution means being located in the vicinity of the opening for suction of the combustion air and for rejection of the combustion products into the ambient air.

Abstract: A retrofit heat recovery device for installation on existing hot air furnaces. The device is arranged to make use of the existing hot pin furnace blower.

Abstract: A recuperative furnace and method for heating wherein the recirculation air blower directs the return air upwardly first to a recuperative heat exchanger and then to a second heat exchanger operating from the heat of combustion. The flue gases are routed directly to the recuperative heat exchanger where a portion of the products of combustion condense. Accordingly, the recuperative heat exchanger not only provides sensible heat transfer from the flue gases but also recovers a portion of the latent heat of vaporization. The second heat exchanger transfers heat from a solution to the recirculation air. The solution flows through a closed loop between the second heat exchanger and a heat transfer module which includes the burner.

Abstract: A method of preventing corrosion in boiler plant equipment when cooling flue gases originating from a combustion plant, such as flue gases containing sulphur oxide or organic acids, to a temperature beneath which sulfuric acid condenses (sulfuric acid dew point temperature) and a further temperature defined as an upper permitted wall-temperature of the stainless steel. The upper permitted wall temperature is with respect to the stainless steel material from which the walls are made and the prevailing partial pressure of water vapor present in the gases. This limiting temperature is specific to each stainless steel. The heat exchange is by means of a coolant, suitably water, located on the other, i.e.

Abstract: For use with a hydrocarbon-fueled furnace whose secondary heat exchanger so cools the combusted gas as to condense much of its water vapor, and having a blower to the flue, a combined trap and drain is provided for the condensate formed both in the heat exchanger and in the flue. At the base of the flue is a standpipe whose upper overflow outlet is connected to a dip tube. Between the level of its lower end and the overflow level is a side inlet into the standpipe, connected to a tube leading downward from the heat exchanger's condenser. When the furnace blower applies both negative pressure to the condenser and positive pressure to the flue, the water levels in the trap and tube adjust to balance out these pressures.

Abstract: A fireplace hood made as a massive solid structure defining the top of the firebox of the fireplace. The solid structure absorbs, stores the heat and radiates it when the fireplace is not in use. The massive structure is preferably made monolithic of a poured refractory material with internal hot gas flues open to a surface of the structure and in communication with the firebox for receiving hot gases. The hot gas flues open to a hot gas accumulator in communication with a tubular member for connection to the fireplace chimney. The fireplace has a convection tube system in its walls for heating cold air from the room in which the fireplace is disposed.

Abstract: A heat exchanger for extracting and recovering waste heat from the flue of a heater, such as a furnace. The present heat exchanger includes a housing having a plurality of sealed, oil filled, parallel metallic finned tubes arranged around the periphery of the heat extractor chamber of the heat exchanger. Hot flue gases from the furnace travel between the inner housing and the outer housing. Thus, the hot flue gases pass through and around the finned tubes thereby heating the oil inside, so that a very large proportion of the heat of the flue gases is extracted by the finned tubes. The plurality of finned tubes are all connected together as one unit exposed to hot flue gases, thus once oil is heated in the tubes, the unit retains the heat even when furnace is not operating. The tubes are made of copper and act as an oil reservoir and heat sink for the heat absorbing fins. A blower exhausts clean heated air out of the rear duct for useful heating.

Abstract: An improved combustion chamber for a condensing furnace comprising an elongated cast body having a mixing chamber for receiving fuel and air and an expansion chamber communicating with said mixing chamber, a fuel inlet in said body communicating with said mixing chamber, an air inlet in said body communicating with said mixing chamber and means for igniting the air fuel mixture in said mixing chamber, the fuel inlet and the igniting means being opposed to one another to enhance the ignition of the fuel and air in the mixing chamber. An important feature of the invention is the critical ratio of the transverse cross sectional area of the expansion chamber to the transverse cross sectional area of the mixing chamber for maintaining continuity of operation. Such ratio should be about 2/1 to 2.4/1. In a preferred form of the invention, the igniting means is a spark plug and the spark plug opening into the mixing chamber is co-axial with the fuel inlet.

Abstract: Disclosed is a dwelling furnace having at least one clam-shell type primary heat exchanger in parallel orientation with a secondary heat exchanger, both the primary and secondary heat exchangers being vertically oriented relative to a furnace housing and parallel to the flow of air to be heated. The primary heat exchanger has a combustion chamber in the lower end thereof, and the lower end of the secondary heat exchanger exhausts into a tertiary heat exchanger oriented approximately perpendicular to the primary and secondary heat exchangers and horizontally relative to the housing, below the combustion chambers of the primary heat exchangers and below the exhaust outlet of the secondary heat exchanger. The tertiary heat exchanger includes a plurality of condensation tubes for retrieving the latent heat of condensation of the combustion gases.

Abstract: In a hot air type heating apparatus having two air outlet ports, a temperature of air current blown out of an auxiliary outlet port provided on an outlet port for a high temperature air is rendered to be at a slightly warm temperature level, thereby realizing an improved hot air type heating apparatus capable of distributing warm air to every corner of a large room to effect uniform room warming, and of removing uncomfortableness to a dweller near the heating apparatus owing to a temperature difference caused by the two air currents blown out of the two outlet ports.

Abstract: A secondary heat exchanger is positioned within a cold air return plenum of a forced air gas or oil fired furnace to preheat cold air drawn into the furnace through the cold air plenum. A heat recovery flue pipe is connected between a primary flue pipe of the furnace and the secondary heat exchanger, and an exhaust pipe is connected between the secondary heat exchanger and the outside of a structure served by the furnace. A secondary blower coupled to the exhaust pipe draws hot combustion gases from the primary flue pipe through the heat exchanger and exhausts cooled combustion gases to the outside. The secondary heat exchanger comprises a combustion gas inlet plenum and a combustion gas outlet plenum, with a plurality of heat conducting pipes sealingly connected therebetween.

Abstract: This invention relates to a compact high efficiency furnace having a cylindrical combustion chamber and a fin and tube type heat exchanger substantially parallel, transverse to the furnace air flow, and closely spaced in the air flow direction with no other major heat exchange being utilized. Condensation of fluids from the combustion gases occurs at the fin and tube type heat exchanger, whereby a high efficiency furnace results. The fins and tubes of the heat exchanger are of different materials, requiring that the combustion gas temperature at the heat exchanger inlet be limited.

Abstract: Disclosed is a dwelling furnace having at least one clam-shell type primary heat exchanger in parallel orientation with a secondary heat exchanger, both the primary and secondary heat exchangers being vertically oriented relative to a furnace housing and parallel to the flow of air to be heated. The primary heat exchanger has a combustion chamber in the lower end thereof, and the lower end of the secondary heat exchanger exhausts into a tertiary heat exchanger oriented approximately perpendicular to the primary and secondary heat exchangers and horizontally relative to the housing, below the combustion chambers of the primary heat exchangers and below the exhaust outlet of the secondary heat exchanger. The tertiary heat exchanger includes a plurality of condensation tubes for retrieving the latent heat of condensation of the combustion gases.

Abstract: A method and apparatus to heat a forced-air supply utilizing hot waste gases in a flue. A flue closure housing is supported by a frame that is arranged to surround an opening in the chimney. The housing supports a heat exchanger having side walls formed of plates with a space between the plates being sealed by end walls to form a flow space for a forced-air supply. The heat exchanger is sealed to a flue closure plate forming part of the flue closure housing. The heat exchanger receives a supply of cold air from a motor-driven blower coupled to a header. Heated air from the heat exchanger is directed by a hot-air discharge header through an opening in the flue closure housing.

Abstract: A device for reclaiming heat from stove pipes and the like. A semi-circular shaped hollow enclosed housing with a highly thermal-conductive concave surface is mounted contactingly to surround approximately one-half of the circumference of the stove pipe. The concave surface is formed to contact the pipe at a maximum number of points along that surface. The hollow interior of the housing contains thin multi-surfaced projections which are integral with the concave surface and conductively transfer heat from the stove pipe and concave surface to heat the air in the housing. A fan blower is attached via an air conduit to an entrance opening in the housing. When turned on, the blower pushes the heated interior air out a plurality of air exit openings in the ends of the housing and brings in lower temperature outside air for heating.

Abstract: Heat exchanger means for extracting heat from the flue gases of a warm air furnace is in the form of a tube wound spirally to define a first passageway wherein ambient air is heated by the flue gases passing through a second passageway between segments of the first passageway for the ambient air, the tube being provided with a deflector directing the flue gases through the second passageway and a shroud for controlling exhaust gases passing through and leaving the convolute tube.

Abstract: A heat saving device is provided for use in connection with the flue pipe of a stove, furnace, or similar heater. Instead of being exhausted directly into the atmosphere through the flue pipe, hot exhaust gases and other combustion products pass through a heat transfer chamber. An open-ended tube forms the inside wall of the chamber so that heat from the gases and other combustion products passing through the chamber is transferred to the useful air flowing through the tube. A removable shroud open at one end and baffled at the other partially surrounds the outer wall of the heat transfer chamber in spaced relationship to the outer wall, permitting flow of useful air through the space thus formed. The useful air flowing through this space is preheated by heat transferred through the outer wall and subsequently entrained by and mixed with air being blown through the inner tube by a fan.

Abstract: A hot water boiler, in particular a light metal central heating boiler, having a combustion chamber and a burned gases flue above the chamber, both the chamber and the flue having a common separating wall with a common water passage, the lower part of the flue, joining the upper part of the combustion chamber, being provided with extensions from the wall for increasing the heat exchange surface thereof and providing a first heat exchanger for the burned gases, the upper part of the flue being provided with inclined ribs extending from the wall to increase the heat exchange surface thereof and forming a second, condensing heat exchanger, the ribs forming condensate collectors cooperating with condensate drains.

Abstract: A flue gas heat recovery apparatus for a forced air type furnace of the type having a furnace heat exchanger, a return air duct and a heated air duct, and a blower for passing air from the return air duct over the furnace heat exchanger to the heated air duct. The heat recovery apparatus includes a secondary heat exchanger mounted in the return air duct having its inlet connected to the outlet of the furnace heat exchanger and an induced draft fan having its inlet connected to the outlet of the secondary heat exchanger and its outlet connected through an outlet flue pipe to the chimney. A vane is mounted in the outlet flue pipe in the path of flow from the induced draft fan and is moved between a closed position when the fan is not operating, to an open position when the fan is operating, and a switch is operated by the vane to operate the burner control after the induced draft is in operation.

Abstract: An apparatus for heating a fluid, as air, having a housing surrounding a heat transfer chamber. A casing having a combustion chamber is located in the heat transfer chamber. A motor driven fan mounted on the housing operates to supply air to the combustion chamber and move air through the heat transfer chamber. Fuel, as waste oil, is metered to the combustion chamber and burned. The air supplied to the combustion chamber moves the burning fuel in a circular pattern to promote combustion of the fuel adjacent the casing thereby heating the casing. The air moved through the heat transfer chamber picks up heat from the hot casing. The heated air is discharged through an open grill into the environment surrounding the apparatus.

Abstract: A heat exchanger and vaporizer adapted for mounting on an existing flue for utilizing heat which is otherwise lost and for providing moisture for space heating and conditioning. The heat exchanger and vaporizer includes a central stack for unimpeded transport of flue gases; a casing, with air inlet and outlet, enveloping the stack; a vaporizor contained within the casing for efficient heat transfer and for room conditioning; and a motor-fan unit for producing an airflow through the casing. The vaporizer is in the form of non-corrosive heat conductive helical tubing for maximizing heat transfer in a given volume, for maintenance free use and for convenience in assembly. The vaporizer is provided with a plurality of vapor vents on its upper surface and a pour spout located externally of the casing.

Abstract: A heat retrieving device is disclosed which directs cool incoming fresh air down a duct within a flue pipe. Hot gasses in the flue pipe heat the incoming air, warming it sufficiently so that it can be discharged directly into a room that is to be heated, thus supplementing the existing heating system. In the preferred embodiment, the upper exterior portion of the exhaust flue is an inverted L-shape that is mounted on a rotatable bearing. A weathervane having an air scoop on one end and both a main vane and a pilot vane on the other end is securely mounted in the horizontal portion of the flue pipe, causing it to rotate into the wind. The upper portion of the duct within the flue pipe is also bearing-mounted and terminates into the fresh air scoop which exits from the flue pipe. Said air scoop is preferably located directly below the air scoop of the weathervane. As the air scoop of the weathervane turns into the wind, the air scoop of the fresh air intake duct also turns into the wind.

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: A recuperative furnace and method for heating wherein the recirculation air blower directs the return air upwardly first to a recuperative heat exchanger and then to a second heat exchanger operating from the heat of combustion. The flue gases are routed directly to the recuperative heat exchanger where a portion of the products of combustion condense. Accordingly, the recuperative heat exchanger not only provides sensible heat transfer from the flue gases but also recovers a portion of the latent heat of vaporization. The second heat exchanger transfers heat from a solution to the recirculation air. The solution flows through a closed loop between the second heat exchanger and a heat transfer module which includes the burner.

Abstract: A fuel-fired fluid heating appliance, such as a gas-fired boiler (FIG. 1) is provided for heating a fluid such as water circulating in a central heating system. The boiler includes a flue 4 for discharging the combustion products, e.g. exhaust gas, to atmosphere by way of a heat exchanger 8 incorporated within a portion 6 of the flue 4 external of the boiler housing 1. The heat exchanger 8 is provided with an inlet 16 to receive water from a return flow pipe 36 and an outlet 17 to discharge the water to the inlet 35 of the boiler primary heat exchanger 3. The heat exchanger 8 (FIG. 2) is provided with a number of ducts 18 along which the exhaust gas travels to transfer its heat to the water circulating within compartments 29 to 33 within the heat exchanger housing 15. The external portion 6 of the flue 4 is disposed at an angle of 20.degree. downwardly to the horizontal so that any exhaust gas condensing in the heat exchanger 8 flows down the flue base 9 to a discharge spout 10 and collector weir 11.

Abstract: This device is a heat capturing, recirculating economizer ventilator, which is sheet metal and is in kit form, to be assembled by the user, for being applied to standing-fireplaces, stoves, and the like. Primarily, it consists of a housing encapsulating a segmented helical configuration surrounding a vertical smooth flue pipe, which automatically forces room ambient air by virtue of a motor driven centrifugal blower, spirally downward on a double path toward and through diffusers, for the purpose of distributing heated air into a space to be heated.

Abstract: A water heater of the combustion type having a collecting assembly for collecting the drain water resulting from combustion to prevent corrosion of components of the heater by the drain water.

Abstract: A metal recuperator is described as having an exterior casing with a replaceable inner housing which forms with the casing a pair of separated fluid passageways through which two fluids, at different temperatures, are circulated into heat exchanging relationship. Special seals are provided to allow relative movement between the casing and the housing while sealing the passageways from each other and the ambient atmosphere.

Abstract: A safe, practical and inexpensive method for saving heat units on modern forced warm air heating furnaces, this method employs a heat exchanger designed by the furnace manufacturer to fit each different size and type of their models. The heat exchanger is interposed directly on the furnace heat exchanger outlet and on through the piping to the flue or chimney. Air circulation through the heat exchanger is provided by the furnace blower by directing air from the warm air supply plenum, with its positive pressure, through the heat exchanger and terminating in separate supply run with a high volume of air which requires no external power to accomplish it. The heat exchanger will be provided with test openings for thermometer readings at the inlet and outlet of flue gas travel through the exchanger. A manual damper may be locked into proper position to restrict air circulation flow if necessary to maintain proper flue gas exit temperature.

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: The present invention provides apparatus for utilizing heat in the flue of the furnace as a heat exchanger and a humidifying source which comprises a flue with a conduit spaced from and concentric with the flue. Means are provided for forcing air from the upper part of the conduit downwardly between the flue and the conduit in a direction opposite to the normal flow of the gases in the flue. Further means are providing for applying moisture to the outer surface of the upper part of the flue within the conduit and above the means for forcing air into the conduit. The heated and humidified air passes downwardly in the conduit and outwardly therefrom and may be connected to the plenum of the furnace. Baffles may be supplied within the flue and within the conduit in order to increase the turbulence of the air and thus increase the heat exchanger which is provided by the system.

Abstract: The invention relates to recuperators used mainly with industrial furnaces, which is provided with a radiation heat exchanger and a convective heat exchanger arranged one behind the other. These known types of recuperators are usable to exploit the waste heat of flue gases only with very low efficiency and have a voluminous and complicated structure.The improvement of my invention is in that the convective heat exchanger has a central heat exchange part and at least one conduit for blowing air on the bottom surface of the central heat exchanger part.The recuperator according to this invention has a longer endurance, a much higher effectiveness and a more simpler, smaller construction.

Abstract: A flue gas heat recovery system for use in conjunction with a forced hot air furnace, such system having two conventional heat exchangers, one located in the flue leading from the combustion chamber of the furnace to the chimney, and the other in the cold air chamber of the furnace adjacent the blower fan. Such heat exchangers each have a core connected into a hydraulic circuit which contains an electrically driven circulating pump controlled by a thermal device having a heat actuated switch located in the upper portion of the heat plenum in the furnace.Such switch is connected into an electric circuit adapted to activate the blower fan and circulating pump simultaneously. The core of the heat exchanger located in the flue of the furnace absorbs a substantial portion of the heat in the exhaust gases which would otherwise be lost to the atmosphere, and utilizes such heat to increase the temperature of the air supplied to the intake of the blower fan in the cold air chamber of the furnace.

Abstract: A flue gas heat recovery apparatus is employed with a system of appliances such as a gas furnace and hot water heater, each having separate exhaust gas flues. The apparatus includes a gas-to-liquid heat exchanger in thermal communication with the two flues to simultaneously extract heat therefrom and a liquid-to-gas heat exchanger disposed within the furnace cold air return duct. A pump circulates water between the exchangers in response to a control signal to employ the recovered heat to preheat the cold air entering the furnace through the cold air return duct. A hysteretic control circuit monitors exhaust gas temperature and provides for system operation between high and low gas temperature limits. In the preferred embodiment of the invention, a furnace blower override feature is employed to energize the blower during periods of pump operation.

Abstract: An air heater comprises a plurality of passes, each having tube banks built into a gas conduit through which passes a flow of heating gas. It also comprises a plurality of delivery and collecting air ducts series-arranged one above the other. The delivery air ducts adjoin the tube banks of each pass and communicate therewith through outlets. The collecting air ducts adjoin the tube banks of each pass and communicate therewith by means of inlets. The collecting air duct is connected to the delivery air duct, the next-in-order along the flow of air, by means of interconnecting air conduits, which are positioned in the interspaces between the tube banks of each individual pass. Each interconnecting air conduit has an inlet orifice adapted to admit a flow of air passing from the collecting air duct, and an outlet orifice through which a flow of air passes from the interconnecting air conduit into the delivery duct.

Abstract: A flue heat reclaimer is constructed to be mounted on the exterior of a flue duct of a heater and provide a spiral-shaped heat transfer passage extending around the flue duct. A fan causes air to flow through the heat transfer passage so that the temperature of this air is elevated by reason at its extended heat transfer relationship with the flue duct.

Abstract: A heat saving and recovery system which includes a rectangular housing insert for a furnace flue gas duct incorporating a coil carrying a heat transfer fluid such was water. The coil communicates with a cold return conduit or other heat transfer device in a forced flow system to transfer heat from the chimney conduit to the return fluid intended to be heated by the furnace.

Abstract: A heating system including a hot water heater and an air duct distribution system employs a housing having a heat exchanger located within its interior in association with a blower. Water conduits lead between the heat exchanger and the hot water outlet and the cold water inlet of the water heater. Water is passed from the hot water outlet of the water heater to the heat exchanger through a water conduit and then returned to a second conduit which passes through a pump to the cold water inlet of the water heater. The pump forcibly moves the water through the above circuit. Heat is exchanged from hot water flowing through the heat exchanger to air which is passed through the heat exchanger by a blower. After being heated the air is forced into the air duct for distribution. The system can be augmented with a second heat exchanger placed in the flue of the water heater.

Abstract: This device is a box unit, which is attached to the furnace exhaust, between the furnace and chimney. It consists primarily of a unit having, at its top, a reservoir containing fluid. Below the reservoir is an arrangement of tubing, through which the fluid is pumped, and exposed to extremely high temperatures. The unit further consists of a baffle, which causes the heat and exhaust fumes to pass upwards over the tubing, to surround the reservoir, and then downwards, and out of the chimney.

Abstract: An attachment for a building furnace which contains a combustion unit inside of an air plenum. The attachment is inserted as a replacement section of the smoke flue. The jacketed chamber acts as a heat exchanger, preheating incoming combustion air. The outer end lower portion of the jacketing chamber receives a fresh air duct from the outside of the building. A duct from the outer end upper portion of the heat exchange chamber leads into the lower portion of the combustion unit plenum at the burners. Attached to the smoke flue, and between it and the outer portion of the chamber, are longitudinally-oriented channeled elements for transferring sensible heat. A return duct from the heated living area leads into the furnace, terminating at the inlet of a blower in the bottom of the furnace. The outlet of the blower is upward into the space surrounding the combustion unit. Such space also joins above the latter to lead upwardly into the heated living area.

Abstract: One exchanger unit comprises a length of exhaust pipe tube having a plurality of smaller heat exchange tubes which extend diametrically through the exhaust pipe tube. Each of the heat exchange tubes is canted slightly longitudinally of the exhaust pipe tube and the heat exchange tubes are disposed in a helical configuration to force the exhaust gases to swirl through the exhaust pipe tube. The heat exchanger units can be disposed in a furnace exhaust pipe or can be arranged between inlet and outlet plenums which are connected in a furnace exhaust pipe or the like.

Abstract: A method and apparatus to heat a forced-air supply utilizing hot waste gases in a flue. A flue closure housing is supported by a frame that is arranged to surround an opening in the chimney. The housing supports a heat exchanger having side walls formed of plates with a space between the plates being sealed by end walls to form a flow space for a forced-air supply. The heat exchanger is sealed to a flue closure plate forming part of the flue closure housing. The heat exchanger receives a supply of cold air from a motor-driven blower coupled to a header. Heated air from the heat exchanger is directed by a hot-air discharge header through an opening in the flue closure housing.