Abstract: A carbon desorption heater (10) for use in a system for removing volatile organic contaminants from a carbon filter is disclosed as having a housing (30) in which a recirculating heating circuit (36) is provided with a recirculation blower (44) that moves the air past a burner (50) for flow through a first flow path (60) of a heat exchanger (58) with a portion of the recirculated air exhausted during each cycle of flow through an exhaust stack outlet (52). A delivery blower (64) within the housing (30) moves air through a second flow path (62) of the heat exchanger (58) for heating prior to delivery to a supply outlet (34). The heater includes a plurality of modules (90) that are sufficiently small so as to be shippable and subsequently securable to each other at the factory site where the heater is to be used.