A heating unit includes a housing defining a thermal cavity, a reflector assembly disposed within the thermal cavity, and a heating element disposed within the thermal cavity. The reflector assembly includes a first reflector coupled to an interior surface of the housing and a second reflector coupled to the first reflector. The first reflector is spaced from the interior surface forming a first air gap therebetween and the second reflector is spaced from the first reflector forming a second air gap therebetween. The heating element is at least partially surrounded by the reflector assembly.