Abstract: A method is disclosed for manufacturing a tube coil useful as a heat exchanger wherein the tube coil comprises a plurality of slightly spaced, parallel tubes wound onto a supporting core. The tubes are wound at an angle to the radial plane of the support. The winding direction is reversed with respect to the radial plane at an odd number of radial angle positions of the coil and separate tubes of a subsequent winding turn are positioned in the spaces between adjacent tubes of the preceeding winding turn.

Abstract: There is provided a heat-exchanger system for heat-exchange between a gas such as air and a liquid such as water, comprising at least one heat exchanger unit which unit comprises at least one tube which is wound to form a hollow coil and which is arranged to conduct said liquid, characterized thereby, that said coil is closed or covered at one end; in that the other end of said coil which is open, is placed against a base plate having an opening which is aligned with the coil opening and has a size and shape corresponding to those of the coil opening; and in that the turns of the coil are slightly separated in order to permit the gas to flow perpendicularly across the tube during the passage through the wall of the coil.