A heat exchanger is assembled in a simple and cost-effective way and needs a
relatively
low space requirement. According to the invention, the tubes (11) are expanded
at the tube ends (16) in such a way that the tube ends (16) are of
rectangular design in cross section. The tube ends (16) have parallel long
connecting surfaces (18) which are brought into bearing contact with long
connecting surfaces (18) of adjacent tube ends (16). Furthermore,
the tube ends (16) have short connecting surfaces (22), onto which
the collecting tanks (23, 29) are placed with their legs (24, 25)
or collars (30, 31). A space-saving heat exchanger can be produced in a
simple way by soldering the long connecting surfaces (18) together, on the
one hand, and by soldering the short connecting surfaces (22) to the collecting
tanks (23, 29), on the other hand.
