What is the definition of a VRF systems HVAC? In the world of HVAC, a VRF system is an acronym for Variable Refrigerant Flow. It is a type of air conditioning system that uses multiple indoor units to provide cooling or heating for a building or area. The VRF system uses a compressor to regulate the flow of refrigerant to the indoor units, allowing for individual temperature control in each room or area. The system is usually composed of an outdoor unit, indoor unit(s), and a control system. It also requires a refrigerant piping system that connects all of the components together. The refrigerant piping system is responsible for delivering the proper amount of refrigerant to each indoor unit to meet the desired temperature. VRF systems are highly efficient, cost-effective, and easy to maintain. By allowing for individual temperature control in each room or area, VRF systems provide an excellent solution for both residential and commercial applications.