vvVAVVariable Air Volume (VAV) is a type of heating, ventilating,and/or air-conditioning system. The simplest VAV system incorporates one supply duct that, when in cooling mode, distributes approximately 55 °F (13 °C) supply air. As the supply air temperature is constant, the air flow rate must vary to meet the rising and falling heat gains or losses within the thermal zone served.

VRF Variable Refrigerant Flow (VRF) vbVRF comes in two system
formats. 1 Heat Pump (HP), a two pipe system that have heating and cooling mode just like a standard HP. Since a VRF system will generally have two or more Indoor Units (IDU), HP IDU’s will all be in cooling or in heating together. Two Heat Recovery (HR), three pipe system that has a special box that controls the flow of suction gas and hot gas through the evaporator, indoor, coils. By switching from suction gas in the coil to hot gas, the indoor unit can be switched from cool to heat while other IDU’s remain in cooling mode.

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