A piece of equipment that is part of the HVAC system and is used to regulate the temperature in spaces or ‘zones’. It is typically installed above the suspended ceiling, below the raised floor or underneath windows along the facade (The latter is an older option not used in Class A buildings.) It is the most popular technical solution used in office buildings in Russia for zoned temperature control. Inside the unit a fan blows air across the coiled pipes. Inside the pipes is a liquid that is heated or chilled by the building’s central systems. To switch between heating and cooling, a 2 pipe Fan Coil Unit system must purge the entire system of one liquid and replace it with the other. A 4 pipe system can be installed to simultaneously carry both cold and hot liquids, so that individual Fan Coil Units can quickly switch between heating and cooling.