A VRF (Variable refrigerant Flow) is an air conditioning system where a single condenser unit can serve multiple indoor units. VRF is available as air-cooled (standard outdoor condenser) and water-cooled. In a water-cooled VRF, heat is rejected to water circulated in a pipe network that serves one or many condenser units. The water is distributed to a heat rejection system (such as a cooling tower or a geothermal heat exchanger). A heat recovery VRF can supply heating and cooling with the capability for heat recovery during periods of simultaneous demand. In addition to providing energy savings through heat recovery, VRFs can eliminate the need for a 4-pipe water system a separate heating appliance and costly gas infrastructure.

Water cooled VRF systems offer improved efficiency when combined with a geothermal water loop – Entering water temperatures can be significantly reduced under peak conditions resulting 20 to 30% less energy consumption compared with an air-cooled unit. Water cooled VRF’s also provide heat recovery opportunities via a common condenser loop for example on a multi-level apartment complex. Several suppliers now offer indoor modules that can produce heating water for underfloor heating and domestic hot water applications, eliminating the need for separator DHW boilers. When combined with a geothermal heat exchanger VRF’s will operate at the highest level of efficiency.