RADIK radiators are flat steel heating bodies with natural flow of air around their transfer areas. Flat heating bodies are produced in a single, double or triple panel design. The primary heat transfer surface of the heating body is made up of a shaped plate with horizontally and vertically alligned channels. In order to increase the heat output of flat heating bodies, additional convector fins are welded to the inner side of the panel on some types. The panel is produced from two pressed shells of sheet steel, which are welded to the vertical channel with spot welds and around the perimeter with seam welds. Cold-rolled sheet steel with a low carbon content is used for flat heating bodies, which corresponds to FePO1 class according to EN 10130 and EN 10131.