Abstract: An air heater for use in association with a radiant heating tube, the air heater comprising a heat exchanger having a combustion air inlet and a heated combustion air outlet, and a heated gas inlet and a heated gas outlet. The heated combustion air outlet has a transfer pipe connected thereto, an opposite end of the transfer pipe adapted to be connected to an inlet end of a radiant heating tube, and the heated gas inlet to the heat exchanger adapted to be connected to a discharge end of said radiant heating tube. The transfer pipe extending from the heated air outlet of the heat exchanger to an entrance to a radiant heating tube has an air control damper means situated therein. The end of the transfer pipe adapted to be connected to an entrance to a radiant heating tube has a venturi portion therein, an oil nozzle means being situated at inlet of the venturi portion of the transfer pipe adjacent the intake end of said radiant heating tube.