Fan coil units (FCU) are simple devices that comprise of a heating or cooling coil and fan. Usually a fan coil unit is not connected to ductwork and it is utilized to control and maintain the temperature of certain spaces. It can be controlled either by a manual on/off switch, or by a thermostat.

FCU can be used in many configurations such as horizontal (ceiling mounted) or vertical (floor mounted) and can be installed in many applications such as residential, commercial, and industrial buildings.