portions extend upward from an inlet flange plate 64 which is readily bolted about the combustion gas outlet in the top planar portion 42 at the left side of the combustion chamber top wall the tubes 62 are bent to extend horizontally and terminate in an outlet flange plate 66 bolted to the radiator inner side wall 52 about its inlet opening 53 in another form of intermediate heat exchangers see fig5 and 6 an inlet flange plate 64 39 mounts a rectangular box portion 71 which extends upward to position a fore and aft manifold 72 at at a level opposite the lower portion 51 of the radiator 50 extending from the manifold 72 to an outlet flange plate 66 39 at a small downward sloping angle which may be 5 u00b0 are a plurality of heat exchange tubes 73 bearing transverse fins 74 the separator shelf 32 mounts a conventional centrifugal blower 80 seen in fig1 and 2 which receives room air drawn in through the door louvers 14 through side openings 81 in the blower scroll to be discharged downwardly as seen in fig1 the right side opening 81 is adjacent to the radiator member 50 at the right side wall 17 of the upper cabinet portion 33 the adjacency of the radiator member 50 to this side inlet 81 somewhat improves the heat transfer from the radiator 50 the.