Variable refrigerant flow

Variable refrigerant flow (VRF) is an HVAC technology invented inJapan by Daikin company in 1982.

VRF uses refrigerant as the cooling and heating medium, and allows one outdoor condensing unit to be connected to multiple indoor fan-coil units(FCUs), each individually controllable by its user, while modulating the amount of refrigerant being sent to each evaporator. 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 required, while the compressor load benefits from the internal heat recovery. Energy savings of up to 55% are predicted over comparable unitary equipment.^[1] VRF is typically implemented with the use of an Air conditioner inverter which adds an DC inverter to the compressor in order to support variable motor speed and thus variable refrigerant flow rather than on/off operation.

While current-technology VRF systems can cost approximately 20 to 40 percent more than a traditional split/heat pump HVAC system to install,operating costs are at least 10 percent less than typical legacy technology. Ramez Afify, an engineer on the technical committee studying VRF air conditioning technology, says that "the difference in price between a VRF and a conventional system might be recovered in fewer than five years"