S18 -- Variable Refrigerant Flow (SI)

Variable-refrigerant-flow (VRF) HVAC systems are a direct-expansion (DX) heat pump technology platform built on the standard reverse Rankine vapor compression cycle. These systems are thermodynamically similar to unitary and other common DX systems, and share many of the same components (i.e., compressor, expansion device, heat exchangers). VRF systems transport heat between an outdoor condensing unit and a network of indoor units located near or within the conditioned space through refrigerant piping installed in the building. Attributes that distinguish VRF from other DX system types are multiple indoor units connected to a common outdoor unit (single or combined modules), scalability, variable capacity, distributed control, and simultaneous heating and cooling. Standards Equipment VRF System Operation Modeling Considerations Design Considerations VRF System Design Example Commissioning