What is the purpose of a fan coil unit?

A fan coil unit is primarily designed to regulate the temperature of a space by circulating air. It accomplishes this through a combination of a fan and a coil. The coil contains either hot or cold water, which is heated or cooled in a central plant or boiler unit. When air passes over the coil, it absorbs or loses heat depending on the temperature of the water, thus effectively heating or cooling the air that is then circulated throughout the room.

In contrast to a unit specifically intended to cool outdoor air, a fan coil unit processes the air within an interior space. Its function differs from standalone dehumidification systems, which focus on moisture control rather than effective temperature regulation. Although fan coil units may contribute to air filtration as air is cycled through them, their primary purpose is temperature control, making circulation and temperature adjustment their main functions.