Abstract: A heat exchange assembly is disclosed, which assembly when placed, for example, in a temperature controlled environment, allows heat exchange between the environment and a fluid passed through the assembly. The heat exchange assembly comprises a plurality of elongated headers each having closed ends and longitudinally arranged inlet holes and outlet holes to provide fluid passage through the header from the inlet holes to the outlet holes transversely to the longitudinal. The headers are interconnected by tubes so that the fluid will pass sequentially through successive headers. Each header may advantageously be provided with a removable plate to allow insertion of cleaning reamers into the inside of the tubes. The heat exchange assembly is adapted to be constructed from readily available materials to form a self-supporting unitary structure.