in the adjacent plate pair the plate pairs are then compressed together whereby the smaller tube is telescopingly received in the larger tube as seen in fig5 fig7 shows an alternative plate design and method of coupling the pipes or tubes between adjacent plate pairs such as plate pairs 110 and 112 tubes 114 and 116 are fabricated having the same diameter and with a length short enough so that they do not overlap when assembled to form the heat exchanger core in this coupling arrangement when the plate pairs 110 and 112 are assembled tubes 116 and 114 are inserted through a collar or retainer ring 118 when the entire heat exchanger is fully assembled and brazed a fluid tight joint is formed between collar 118 and tubes 116 and 114 as shown in fig5 and 7 neither the tubes 64 66 114 116 nor the plate pairs 18 in the region of the apertures are formed with spacing means or devices to position the tube 64 114 of each upper plate with respect to the tube of the lower plate 16 connected thereto in the axial direction of the tubes the absence of such spacing means is advantageous in the construction and assembly of the heat exchanger because it helps ensure that the distance between adjacent plate pairs in the heat exchanger will correspond to the height of the fins used a stronger more robust heat exchanger is achieved by relying upon the fins to properly space the plate pairs by omitting such spacing means the assembly is less sensitive to relational height variability between spacing abutments as used in the aforementioned u k patent a 1 305 464 or between.