(57) A new method of manufacturing of heat exchangers, and more particularly a method of producing completely integrated heat exchanging modules of variable size and capacity, and heat exchangers provided by such method is disclosed. The method comprises steps of providing a hollow shape (2) comprising a tube (21) with one or more voids, longitudinally extending fins (22) projecting from the tube surface, partial removal of fins and bending of the tube in areas free of fins providing a meander-like loop for heat exchanging medium and a multiplicity of convection chambers (24). The heat exchanging module (2) is also provided with apertures (25,26) constituting inlets and outlets for transverse circulation of heat exchanging media.