Variable refrigerant flow (VRF) Like ductless minisplits VRFs 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).
VRFs are typically installed with a DC inverter in order to support variable motor speed to the compressor and thus variable refrigerant flow rather than simply 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. . Energy savings of up to 55% are predicted over comparable unitary equipment. This also results in greater control of the building's interior temperature by the building's occupants.
VRF systems have been used in Japan since the 1980s. Currently, in Japan, VRFs are used in 50% of mid size office buildings (up to 70,000 ft2 or 6,500 m2) and 33% large commercial buildings (more than 70,000 ft2 or 6,500 m2)
Although these systems have been around for almost three decades, they’re relatively new to the U.S. HVAC market.
VRF systems offer an energy-efficient solution that provides considerable flexibility. VRF systems are a good option for buildings with varying loads and different zones and are a great alternative to chill water systems by getting rid of the costly maintenance that goes with chill water such as water treatment, boilers etc.