Abstract: A plastic tubular heat exchanging element consists of a tube or tubular element comprising an inner wall and an outer wall interconnected by partitions, thereby forming longitudinal channels.The channels are connected with a fluid supply chamber and a fluid outlet chamber for feeding and removing a heating fluid. Preferably a supply chamber and outlet chamber are formed by a tubular sleeve, sealingly engaging a wall of the heat exchanging element by applying sealing rings.The supply chamber and outlet chamber may be located near the ends of the tubular heat exchanging element. The chambers may also be opposite each other while the other end of the tubular element is closed by a covering cap forming a chamber for passage of heat absorbing fluid from the supply chamber toward the outlet chamber, located at the same end.