A rotary compressor machine, such as a combustion air charger, includes a rotatable shaft (18) having at least one compressor wheel (20,22) thereon and disposed within a housing (12,14). A donut-shaped heat exchanger (36) is located within the housing (12,14) between the compressor wheel (22) and an outlet (32) from the housing and has radially inner and outer peripheries (40,42). The outer periphery (40) defines an inlet for the heat exchanger (36) for gas discharged by the compressor wheel (20). The heat exchanger is provided with radially inner and outer flow paths defined by tubes (92) and includes a combined manifold and tank (44) which is secured and sealed to a header plate (88) receiving the tubes (92). The combined manifold and tank (44) includes first, second and third axially spaced walls (96,98,100) with each having a central opening (110,112,114). The first wall (96), at its central opening (110) is sealed and mounted to a header plate (88) at its radially outer periphery while the second wall (98), at its central opening (112), mounts a baffle (116) that extends axially to and abuts the header plate (88) to separate the radially inner and outer flow paths. The third wall 100), at its central opening (114), includes an annular, axial extension (120) sealingly secured to the header plate (88) at its radially inner periphery.