A radiant tube assembly comprises a radiant tube having a burner leg, an exhaust leg and a recuperator inside the exhaust leg and in a stream of products of combustion flowing in the exhaust leg. The recuperator has an air intake port at a first end and a mixing baffle at a second, hot end. The mixing baffle causes combustion air and products of combustion to be mixed at the hot end of the recuperator and provided to the burner leg for combustion. The mixing baffle includes a flow director which increases the amount of products of combustion mixed with the combustion air. The mixing baffle can also include a dome-shaped end which extends into the stream of products of combustion for reducing turbulence of the stream of products of combustion flowing in the exhaust leg.