A fan coil unit (FCU) is a simple device consisting of a heating and/or cooling heat exchange or ‘coil’ and fan. It is part of an HVAC system found in residential, commercial, and industrial buildings. A fan coil unit is a diverse device sometimes using duct work and is used to control the temperature in the space where it is installed or serve multiple spaces. It is controlled either by a manual on/off switch or by a thermostat which controls the throughput of water to the heat exchanger using a control valve and/or the fan speed.
The coil receives hot or cold water from a central plant, and removes heat from or adds heat to the air through heat transfer. Traditionally fan coil units can contain their own internal thermostat or can be wired to operate with a remote thermostat