variable refrigerant flow The VRF systems Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an HVAC technology invented in 1982. [1] Like ductless minisplits VRF system use refrigerant as the cooling and heating medium. This refrigerant is conditioned by a single outdoor condensing unit, and is circulated within the building to multiple fan-coil units (FCUs) . Description Variable refrigerant flow VRF system VRFs are typically installed with an Air conditioner inverter which adds a DC inverter to the compressor in order to support variable motor speed and thus variable refrigerant flow rather than simply perform on/off operation. By operating at varying speeds, VRF units work only at the needed rate allowing for substantial energy savings at partial-load conditions. Heat recovery VRF technology allows individual indoor units to heat or cool as require...