A heat exchanger assembly is provided including a multi-function boiling chamber having a top wall and a bottom wall parallel to the top wall and a first side wall and a second side wall both extending inwardly from the bottom wall to the top wall and a pair of end walls closing the chamber. First and second condensing tubes attached to the first and second side walls, respectively, of the boiling chamber have an elongated width presenting an upper surface and a lower surface and extend in opposite respective directions to distal ends of the tubes at an inclined angle relative to the bottom wall of the boiling chamber. The condensing tubes include a plurality of channels across the width and extending from the boiling chamber to the distal end of the tube. A tank disposed at each of the distal ends of the condensing tubes is in fluid communication with the channels tubes. Upper air fins extending upwardly in a plane containing the top wall of the boiling chamber and lower air fins extending downwardly in a plane containing the bottom wall of the boiling chamber engage the respective upper and lower surfaces of both condensing tubes between the respective side walls of the boiling chamber and a position adjacent the respective distal ends of the condensing tubes.