Variable Speed Drive
(VSD): Refrigeration systems in air to air heat pumps are often subject to wide variations in capacity and demand. A VSD system uses electronic speed control to vary the speed of the compressor motor. The motor speed can be increased to compensate for low ambient temperature conditions when less heat is available to use or decreased during mild weather. VSD systems are capable of high energy efficiencies because they match the unit’s capabilities to demand. Also known as VRV (Variable Refrigerant Volume) and VRF (Variable Refrigerant Flow).
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