Cover Feature
PUMP UP THE VOLUME Variable refrigerant volume air conditioning systems – or variable refrigerant flow, as it is more widely known – have grown in popularity since they were first introduced in the early 1980s. As Sean McGowan reports, there are a few reasons why VRF is on the rise. DON’T BE FOOLED
IN THE BEGINNING
VRV (variable refrigerant volume) and VRF (variable refrigerant flow) are not two different systems. They are one and the same, and have been around a lot longer than you might have expected, too.
Before the development of Daikin’s VRV technology in 1982, achieving individual zone control for air conditioning in commercial buildings was considered a challenge. But the arrival of VRV changed that concept.
The world’s first VRV system was introduced by Daikin in 1982. The company promptly trademarked the term. This meant that when other manufacturers later developed the technology it was described as VRF rather than the proprietary term.
Why? Because VRV/VRF varies the refrigerant volume in a system to match the building’s requirements. It does this by allowing the outdoor unit (compressor) to supply varying amounts of refrigerant to multiple indoor units (fan coils) located throughout the building.
Eventually, VRF became the industry-standard term, with the exception of Daikin, which continues to use VRV today. Although 40 years have since passed, VRF air conditioning systems are still considered to be relatively sophisticated. They have benefited from continuous development over the decades, with improvements including increased capacity load and the incorporation of heat-recovery technologies. 20
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Each indoor unit has a valve to control the volume flow rate of refrigerant Summer 2021
As each indoor unit experiences different heat loads in the space it serves, the outdoor unit is able to supply the appropriate amount of refrigerant to those indoor units. “Refrigerant is pumped from the outdoor unit to each indoor unit,” says Daikin Australia Engineering Support Manager Blake Mortimer, M.AIRAH. “Each indoor unit has a valve to control the volume flow rate of refrigerant to ensure the precise amount of refrigerant is fed to the indoor heat exchanger.” Heat pump VRF systems will only allow all indoor units to operate in either heating or cooling mode. Heat recovery VRF systems allow each unit to operate in either mode. The addition of a branch selector box allows the indoor unit to switch between these modes. At the heart of VRF technology is control logic at the outdoor unit that allows the indoor units to communicate with it.
