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What is the Variable Refrigerant Flow (VRF) Systems?

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257 views asked May 4, 2015 by Matt Hall

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Variable Refrigerant Flow (VRF) and also called Variable Refrigerant Volume (VRV)  is an air-condition system configuration where there is one outdoor condensing unit and multiple indoor units. The term variable refrigerant flow refers to the ability of the system to control the amount of refrigerant flowing to the multiple evaporators (indoor units), enabling the use of many evaporators of differing capacities and configurations connected to a single condensing unit. The arrangement provides an individualized comfort control, and simultaneous heating and cooling in different zones.

The VRF technology uses an inverter-driven scroll compressor and permits as many as 48 or more indoor units to operate from one outdoor unit (varies from manufacturer to manufacturer). The inverter scroll compressors are capable of changing the speed to follow the variations in the total cooling/heating load as determined by the suction gas pressure measured on the condensing unit. The capacity control range can be as low as 6% to 100%.


Outdoor units are available in sizes up to 50 ton.

This system can cool one zone while heating another. Set up zones to maximize simultaneous operation: interior/perimeter or eastern/ western exposure. Each zone gets the cooling or heating that is needed at any time

(Fig. 1).


Integration of Outside Air. Ventilation systems used in conjunction with VRF systems are engineered separately on a case- by-case basis. Manufacturers are evaluating potential approaches for an integrated solution, incorporating controls to ensure adequate outside air and economizing, while optimizing overall performance.

answered May 4, 2015 by Matt Hall

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