2-pipe and 4-pipe systems

Fan coil units are divided into 2-pipe and 4-pipe devices.

The 2-pipe fan coil units have one supply and one return pipe. The supply can feed warm or cold water. However, the 2-pipe devices can either solely heat or solely cool depending on which medium is flowing through the pipe system.

4-pipe fan coil units have two supply and two return pipes and can therefore be fed with warm and cold water at the same time. This is sensible in particular in buildings with large temperature differences where the cooling and heating functions are needed at the same time (for example, equipment room vs. wellness area or also hotel rooms with a southern aspect vs. hotel rooms with a northern aspect).