A fan coil unit is a simple device consisting of a fan and a heating/cooling exchanger or 'coil'. It's part of an HVAC system commonly found in residential, commercial, and industrial buildings.
A fan coil unit is used to control the temperature in a localized space where it's installed by blowing air through connecting ductwork. It's controlled either by a manual on/off switch or by a thermostat, which controls the flow of hot or cold water to the coil using a valve actuator and fan speeds. Larger spaces may include several fan coil units to heat/cool the various living zones.
Due to their simplicity and flexibility, fan coil units can be more economical to install than ducted 100% fresh air systems (VAV) or central heating systems with air handling units or chilled beams, especially in highrise and multi-tenant buildings. Various unit configurations are available, including horizontal (ceiling mounted) or vertical (floor mounted).