Abstract: A fuel-fired furnace incorporates specially designed fuel/air mixing and combustion structures. The fuel/air mixing structure is of a mixing sound-attenuating design and comprises a venturi having a perforated sidewall portion and being surrounded by a noise-damping housing chamber communicating with the interior of the venturi via its sidewall perforations. During use of the mixing structure, air is flowed through the venturi in a swirling pattern while fuel is transversely injected internally against the swirling air. The combustion structure comprises a burner box housing into which the fuel/air mixture is flowed, combusted, and then discharged as hot combustion gas into and through the heat exchanger tubes. The fuel/air mixture entering the burner box housing initially passes through a non-uniformly perforated diffuser plate functioning to substantially alter in a predetermined manner the relative combustion gas flow rates through the heat exchanger tubes.

Abstract: To substantially reduce inequality in hot combustion flow rates through first and second heat exchanger tubes from a fuel-fired heating appliance burner box connected thereto and internally combusting a fuel/air mixture received therein from a source thereof to create the hot combustion gas, a perforated diffuser member having a non-uniform perforation pattern is provided. The fuel/air mixture is flowed through the perforated diffuser member into the interior of the burner box. The non-uniform perforation pattern of the diffuser member functions to alter relative combustion gas flow rates through the first and second heat exchanger tubes in a manner reducing an undesirable operating temperature differential therebetween.

Abstract: Apparatus and methods are provided for compensating for high altitude reduction in the heating capacity of a gas heating appliance, illustratively a gas-fired heating furnace. In a representative embodiment of such apparatus and methods the regulated pressure of the furnace gas valve, and the speeds of its combustion and indoor blowers, are coordinatingly increased to provide the furnace with a substantially unchanged maximum heating output despite its new higher altitude location.

Abstract: A water heating system including a water container having a cold water inlet that connects to a water supply, a hot water outlet, a water heater outlet and a water heater inlet; an instantaneous water heater mounted to the water container and having a tank supply inlet connected to the water heater outlet, a tank supply outlet connected to the water heater inlet, a burner, and a heat exchanger located adjacent the burner between the tank supply inlet and the tank supply outlet; a pump connected between the water container and the instantaneous water heater that moves water between the water container and the instantaneous water heater; and a controller that operates the pump and the burner.

Abstract: A water heater including a water reservoir container having a cold water inlet and a hot water outlet, a combustion chamber adjacent the water container, a burner associated with the container; a temperature probe associated with the container that detects a water temperature in an upper portion of the container, and a controller that activates the burner, the controller establishing an initial water temperature set point, comparing detected water temperature with the set point when the burner is activated, reducing the set point by a first selected amount when the water temperature decreases by less than a selected amount while the burner is activated or increasing the set point by a second selected amount when the water decreases by a selected amount of more while the burner is activated.

Abstract: A water heater including a water container, a combustion chamber adjacent the water heater, a burner associated with the combustion chamber and arranged to combust fuel to heat water in the water container, a flue having an upper portion and a lower portion operatively connected to the combustion chamber and extending through at least a portion of the water container, and a catalytic converter located in the upper portion of the flue. The water heater may also reduce NOx and CO emissions generated by a water heater having a radiant burner including activating the burner in response to the temperature of water in the water heater as needed, and substantially removing accumulated foreign matter on the burner by periodically activating the burner irrespective of the water temperature for a selected amount of time.

Abstract: A low NOx water heater including a water container; a combustion chamber adjacent the water container; and a burner associated with the combustion chamber and arranged to combust fuel to heat water in the water container, the burner comprising a plenum chamber having a combustion surface and a device to detect the presence of the collection of lint, dirt and/or oil.

Abstract: A water heater including a water container; a combustion chamber adjacent the container, the combustion chamber having at least one air inlet to admit air and extraneous fumes into the combustion chamber and confine ignition and combustion of the extraneous fumes within the combustion chamber; a burner associated with the combustion chamber and arranged to combust fuel to heat water in the container; and an air diverter positioned between the air inlet and the burner and adapted to channel at least a portion of combustion air passing through at least a portion of the air inlet to a position for mixture with the fuel prior to entering the burner to slow combustion and thereby reduce combustion temperatures and NOx emissions.

Abstract: A water heater including a water container; a combustion chamber adjacent the container, the combustion chamber having at least one air inlet to admit air and extraneous fumes into the combustion chamber and confine ignition and combustion of the extraneous fumes within the combustion chamber; a burner associated with the combustion chamber and arranged to combust fuel to heat water in the container; and an air diverter positioned between the air inlet and the burner and adapted to channel at least a portion of combustion air passing through at least a portion of the air inlet to a position for mixture with the fuel prior to entering the burner to slow combustion and thereby reduce combustion temperatures and NOx emissions.

Abstract: A water heater has a water container and an element located to heat water in the water container. A sensor located to sense temperature proximate the element and a controller connected to the element and the sensor. The controller is programmed to compare a plurality of sensed temperatures and to disengage the element in the event that the difference between sensed temperatures over a predetermined time period is greater than a predetermined temperature difference and further to engage the element based on a comparison of sensed tempereatures.

Abstract: A water heater heating element including a base member adapted to extend through and sealingly engage a wall of a water heater tank, the base member having a recess; a thermistor positioned in the recess; members connected to the thermistor and extending outwardly of the base member to transmit temperature information; a sheathing sealed to and extending outwardly from the base member; a heating coil positioned within the sheathing; cold pins connected to opposed ends of the heating coil and to the base member, the cold pins being sufficiently long that heat generated by the heating coil is not detected by the thermistor; and members connected to the cold pins and extending outwardly of the base member to transmit power to the heating coil.

Abstract: A water heater of the invention includes a water container; a combustion chamber adjacent the water container; a burner associated with the combustion chamber; a flue connected to the combustion chamber; a blower assembly positioned to receive combustion products from the flue and convey the combustion products to a remote location; and a pressure switch positioned to detect blockage of combustion products away from the blower assembly and flow of air from the flue prior to initiation of combustion in the combustion chamber.

Abstract: A water heater comprising a water container; a combustion chamber adjacent the water container; a burner associated with the combustion chamber; a flue connected to the combustion chamber; a blower assembly positioned to receive combustion products from the flue and including a blower; at least one inlet having a plurality of ports which permit air and extraneous fumes to enter the combustion chamber and prevent combustion of extraneous fumes outside of the combustion chamber; a temperature sensor positioned adjacent the inlet; and a controller connected to the blower and the temperature sensor, the controller being capable of activating the blower in response to temperature changes detected by the temperature sensor.

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

Abstract: A compact, high efficiency heat exchanger for a fuel-fired forced air furnace has horizontally spaced apart inlet and outlet manifold structures which are innerconnected by a horizontally spaced series of vertically serpentined, relatively small diameter flow transfer tubes. Larger diameter inlet flow tubes are positioned beneath the balance of the heat exchanger, extend parallel to the transfer tubes, and have upturned discharge ends connected to the underside of the inlet manifold. The heat exchanger is configured so that its total vertically facing peripheral surface area is considerably larger than its total horizontally facing peripheral surface area, thereby signficantly reducing undesirable outward heat loss through the vertically extending furnace housing side walls upon burner shut off and increasing the overall efficiency rating of the furnace.

Abstract: An induced draft, fuel-fired upflow furnace is provided with a compact, high efficiency heat exchanger having horizontally spaced apart inlet and outlet manifold structures which are innerconnected by a horizontally spaced series of vertically serpentined, relatively small diameter flow transfer tubes. Larger diameter inlet flow tubes are positioned beneath the balance of the heat exchanger, extend parallel to the transfer tubes, and have upturned discharge ends connected to the underside of the inlet manifold. The heat exchanger is configured so that its total vertically facing peripheral surface area is considerably larger than its total horizontally facing peripheral surface area, thereby significantly reducing undesirable outward heat loss through the vertically extending furnace housing side walls upon burner shut off and increasing the overall efficiency rating of the furnace.

Abstract: A fuel-fired, condensing type forced air heating furnace is provided with an improved hot combustion gas-to-air heat exchange system which includes a generally drum-shaped primary heat exchanger having an outlet end connected to a first end of a transfer manifold whose second end is connected the inlet end of a fin-and-tube type secondary heat exchanger which is spaced laterally apart from, faces, and extends generally parallel to the primary heat exchanger. A radial discharge fuel burner end portion is coaxially positioned within an inlet end of the primary heat exchanger and, during furnace operation, a draft inducer fan draws burner combustion gases sequentially through the primary heat exchanger, the transfer manifold and the secondary heat exchanger while air to be heated is flowed externally over these heat transfer elements.

Abstract: In an inducted draft, fuel-fired furnace a flow restriction in the external exhaust flue is detected, and the furnace burners responsively deactivated, by a thermal sensing switch mounted in a spaced relationship with a small flow opening formed in a sensor housing externally secured to the inducer fan outlet section over a wall opening therein. During normal burner combustion product discharge flow through the exhaust flue, a small vane within the inducer fan outlet section creates a venturi therein which draws ambient air within the furnace housing across the temperature sensing switch and into the fan outlet section through the sensor housing opening. The temperature of this ambient air is below the switch set point so that continued burner operation is permitted.