Condenser in horizontal design with non-exchangeable straight-tube bundle. The bundle tubes can be cleaned easily after the disassembly of the heads. The interior of the shell is not accessible. The bundle tubes are attached by expanding or shrink-welding or both (depending on the operating conditions). Condensate supercooling is partly possible but there is a fill level limitation necessary. The heat exchanger is controlled by a steam control valve. Depending on the operating conditions a compensator may be required to compensate for expansion. There is no strong barrier layer formation due to inert gases as in narrow channels (e.g. plate heat exchangers).