Abstract: A gas-fired radiant tube that employs heterogeneous catalytic combustion, and a high combustion efficiency, low NO.sub.x catalytic combustion radiant tube heating system, incorporating the radiant tube, are disclosed. In the system, essentially mirror image, combined inlet/exhaust units containing heat regenerator units are connected at opposite ends of the catalytic combustion tube. Combustion flow is cycled back and forth through the units and the combustion tube so that during any given cycle the hot exhaust gases heat the regenerator in the exhaust side of the flow for preheating the inlet gases during the next, reversed flow cycle and the natural gas fuel is completely oxidized. Thus, the cycled flow completely consumes the fuel and constantly preheats inlet air so that the sytem provides both high combustion efficiency and high thermal efficiency.

Abstract: Zone-controlled radiant burners are provided for retrofit installation in existing heaters. The burners comprise hollow cylindrical fiber matrix layers with baffles forming separate plena. A main stream of pre-mixed fuel and air is directed into the middle plenum, with the mixture flowing through the fiber matrix layer and incandescently combusting on the active surface zones to radiantly heat the tube coils. A reduced flow of fuel/air mixture, or only air, is directed into the remaining plenum so that the surrounding surface zones are combustibly less active or inactive to avoid destructive overheating of the burner surfaces.

Abstract: A fired heater incorporating radiant tube sections in the combustion chamber. Radiant burners mounted in the chamber side walls combust reactants flamelessly and transfer thermal energy inwardly to the radiant section tubes. Certain of the embodiments include tube coils forming convection sections with gaseous products of combustion flowing in heat exchange relationship with the convection section tubes after which they are channeled into a flue.

Abstract: Water heaters are provided which exhibit improved efficiency and emissions performance over conventional water heaters, comprising condensing heat exchanger means and infrared fiber matrix burner means to achieve said improved performance.

Abstract: A gas-fired, forced air furnace system employing a fiber matrix burner element and a condensing-type heat exchanger to achieve both high system thermal efficiency and low emission of NO.sub.X and other gaseous pollutants. The value of excess air in the fuel-air reactants supplied to the ceramic fiber matrix burner is selected to be equal to or greater than ten percent to provide NO.sub.X emissions below fifteen ppm on an air-free basis, with CO and HC emissions substantially comparable to those from existing furnaces, and the surface area of the condensing portion of the heat exchanger system is designed to produce sufficient condensation of moisture in the combustion gasses to produce an overall system thermal efficiency of at least about ninety percent.

Abstract: A gas-fired, forced air furnace system employing a fiber matrix burner element and a condensing-type heat exchanger to achieve both high system thermal efficiency and low emission of NO.sub.X and other gaseous pollutants. The value of excess air in the fuel-air reactants supplied to the ceramic fiber matrix burner is selected to be equal to or greater than ten percent to provide NO.sub.X emissions below fifteen ppm on an air-free basis, with CO and HC emissions substantially comparable to those from existing furnaces, and the surface area of the condensing portion of the heat exchanger system is designed to produce sufficient condensation of moisture in the combustion gasses to produce an overall system thermal efficiency of at least about ninety percent.