What is the definition of a VRF HVAC system? A Variable Refrigerant Flow (VRF) HVAC system is a type of heating, ventilation, and air conditioning system that uses variable refrigerant flow to regulate the temperature in a building. It is a more efficient system compared to traditional HVAC systems and can serve multiple rooms simultaneously. The system works by using an outdoor compressor which is connected to multiple indoor air handlers. The compressor contains a refrigerant which is compressed and circulated to the air handlers. The air handlers then distribute the properly cooled or heated air throughout the building. The VRF system can be adjusted to provide different levels of cooling or heating to different areas within the same building, allowing for greater control and energy savings. A VRF HVAC system is also relatively quiet compared to other types of HVAC systems and is a great choice for buildings with multiple rooms or levels.