Variable Refrigerant Flow (VRF), also known as Variable Refrigerant Volume (VRV), is a type of multi-split type central air conditioning system. It uses a refrigerant as a medium for transmitting cold and heat. This refrigerant is conditioned by an outdoor condensing unit and then circulates through the building to multiple indoor units.

It was invented in Japan by Daikin in 1982, a company that later patented that name (VRV), and this was only possible with the application of modern digitalized control techniques.

Subsequently, the rest of the industry adopted the generic name "VRF" (from the English "variable refrigerant flow"), which is also more appropriate since the entire process is always carried out in a closed environment, that is, at CONSTANT VOLUME, since what varies is actually the flow of the fluid (the amount that is pumped at each moment), depending on the needs of the remote units.

Like simple split systems, VRF systems use a fluid as a cooling and heating medium. This is conditioned by an external condensation unit and circulated within the construction through tubes that connect to multiple remote units, distributed in one or several rooms.

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