Condenser in vertical 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 and can only be inspected through the connection nozzles. The bundle tubes are attached by expanding or shrink-welding or both (depending on the operating conditions). The supercooling of condensate is possible. It is possible but not useful to control the heat exchanger by the accumulation of condensate. If inert gases are present, it is not possible to control the heat exchanger through the accumulation of condensate. Depending on the operating conditions a compensator may be required to compensate for expansion. The condenser is equipped with a condensate collector and a LIC connection nozzle for possible condensate pump control. Inert gases can be easily discharged. There is no strong barrier layer formation due to inert gases as in narrow channels (e.g. plate heat exchangers).