VRF, is a type of heating and cooling system for residential or commercial applications. In order to understand how VRF is unique, it’s helpful to understand the basics of common HVAC systems. Most heating and cooling systems fall within two broad categories: ducted split systems or ductless, mini-split systems like the packaged terminal air conditioning found in many hotel rooms. These systems use refrigerant (older units used R-22, newer ones R-410A) and a water-based system to cool air.