A thermal process device for heat treating a product or plurality of products includes a thermal processing chamber having opposed distal ends and a plurality of controllable heating zones. At least one buffer zone is disposed at each of the distal ends. The buffer zones and heating zones of the thermal processing chamber form a heating element assembly. The heating assembly has an inner and outer surface and a secondary shell is disposed about the outer surface of the heating element assembly and spaced therefrom to form an inlet flow passage for a flow of a temperature adjusting medium along the heating element assembly. A flow directing arrangement is configured to direct the flow of the temperature adjusting medium in the inlet flow passage to the different zones of the heating assembly to adjust the temperature in the heating zones, wherein a majority of the flow of the temperature adjusting medium is delivered to a central zone of the heating temperature assembly and then outward toward at least one of the distal ends.