A radiator is disclosed for mounting in an upright position to a wall, comprising a front panel and a back panel between which an interior space is provided for introducing a fluid. The back panel is made of a heat-conductive material and is provided with fluid supply and drainage fittings for supplying and draining the fluid to and from said interior space. The back panel is further provided with cooling ribs for exchanging heat with surrounding air and mounting brackets for mounting the radiator on a wall. The front panel has pre-formed canals for directing the fluid flow in a controlled way from the supply fitting to the drainage fitting. The front panel is made of a synthetic material which is substantially non-heat-conductive. A seal is provided between the panels for making said interior space substantially fluid-tight. The front and back panels are assembled with the seal in between by means of bolts.