A fan coil unit (FCU), also known as a Vertical Fan Coil-Unit (VFC), is a device consisting of a heat exchanger (coil) and a fan. As part of an HVAC system found in residential, commercial, and industrial buildings, a fan coil unit is often connected to duct work and a thermostat to regulate the temperature of one or more spaces as well as assisting the main air handling unit for each space. The thermostat controls the fan speed and/or the throughput of water to the heat exchanger using a control valve.