What is the definition of a VRF in HVAC? VRF stands for Variable Refrigerant Flow and is a type of HVAC system. It is a new technology in the field of air conditioning, heating and cooling systems. VRF systems are capable of delivering efficient heating and cooling for a wide variety of applications. The system works by using a variable-speed compressor which adjusts the flow of refrigerant based on the temperature of the space. This allows for a greater level of temperature control and energy efficiency. The system can provide comfortable temperatures throughout the building, but also has the ability to zone the building and provide different temperatures to different areas. VRF systems are becoming increasingly popular as they provide greater energy efficiency than traditional HVAC systems, as well as improved comfort for those who are using the system.