MEP Engineering · Engineering Glossary
Variable Refrigerant Flow (VRF) is an HVAC system technology that uses refrigerant as the heat transfer medium, circulating it directly between one or more outdoor condensing units and multiple indoor fan coil units throughout the building. VRF systems are known for their flexibility, individual zone control, and high energy efficiency.
A heat-recovery VRF system can simultaneously heat some zones and cool others by transferring heat energy between zones, making it especially efficient for interior zones with different load profiles. VRF is popular for multi-tenant commercial buildings, hotels, and mixed-use projects where individual zone control and tenant sub-metering are desirable. The refrigerant piping runs from the outdoor unit through a branch circuit controller to each indoor unit, requiring careful routing to stay within manufacturer length and elevation limits. Design considerations include refrigerant charge calculations, ventilation for enclosed mechanical spaces, and coordination with the structural engineer for outdoor unit placement.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
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