Abstract: A multi-tube heat exchanger includes a pair of tanks and a plurality of heat transfer tubes fluidly interconnected between the tanks, wherein each heat transfer tube has an engaging portion only at a first end portion engaging a wall of a first tank of the pair of tanks and a relatively movable portion at a second end portion capable of moving in an axial direction of the tube relative to a wall of the second tank. Such a structure helps ensure proper tube positioning and spacing while bowing or deformation of the heat transfer tubes is appropriately prevented at the time of heating and brazing.