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What Is Variable Refrigerant Flow?

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Variable refrigerant flow (VRF) system installations are increasing as the heating and cooling source in hotels, schools, and multifamily residential buildings. The VRF industry is expected to grow by 10.8 percent from 2016 to 2021. 1 What is VRF and why is its popularity increasing?

Introduction to Variable Refrigerant Flow

Unlike traditional central air conditioners, variable refrigerant flow systems do not rely on ductwork to carry conditioned air throughout a building. VRF units are considered to be enhanced versions of multi-split systems, including those that use heat pumps. 2 They consist of an outdoor condensing unit connected to multiple indoor evaporator units by refrigerant-filled copper tubing. A refrigerant, usually R-410A, is the working, heat-transfer fluid. The compressor heats or cools the refrigerant, which is then sent into the building to condition the air.

A variable speed drive controls the compressor, allowing it to regulate and vary the flow of refrigerant through the multiple evaporator coils. This results in individualized temperature control for each comfort zone, a process also known as zoning. The system can heat and cool separate rooms simultaneously. It can also transfer the energy from rooms that are being cooled to ones that are being heated. 3 4

Variable Refrigerant Flow Applications

European and Asian countries were early adopters of variable refrigerant flow systems, but the technology is gaining in popularity in the U.S. While VRF technologies hold 24 percent of the global commercial air conditioning market, they account for 3 percent of the U.S. market. 5

Sectors that stand to benefit the most from VRF systems are those with buildings that require zoning or that cannot support ductwork. Compared to HVAC systems that are older or that only meet minimum efficiency requirements, VRF systems can save building owners 30 percent on utility bills. Some of the greatest applications of the technology can be found in K-12 schools, hotels, and commercial offices. It’s also popular in multifamily housing developments. 6 Hospitals have also been converting to VRF systems to save energy. 7

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Variable Refrigerant Flow Pros and Cons

As with any HVAC equipment, variable refrigerant flow systems have some important advantages and disadvantages.

Pros

  • Efficiency: 30 percent more efficient than conventional HVAC systems.
  • Installation: Easier installation thanks to lightweight, modular equipment. 8
  • Flexibility: Don’t require ductwork. Simultaneous heating and cooling capabilities.

Cons

  • Limitations: Not ideal for year-round cooling in colder climates. 9
  • Cost: Upfront costs can be high. 10
  • Unfamiliarity: Difficult to find contractors and maintenance technicians who are familiar with the technology. 11

Demand for Energy Efficiency

HVAC systems can account for up to 40 percent of the electrical energy usage in a building. As the supply of fossil fuels to generate electricity continues to diminish, demand for high efficiency HVAC equipment is expected to rise. 12 Learning about new technologies like variable refrigerant flow systems could prove helpful to individuals currently in HVAC/R training, as they may work with such equipment when they graduate.

Sources:

1 – http://www.achrnews.com/articles/133041-hvac-industry-embracing-vrf-solutions
2 – http://www.csemag.com/single-article/back-to-basics-vrf-systems/0609c3a8a2a2c14fe272e95f18e0a97e.html
3 – https://www.gsa.gov/portal/mediaId/197399/fileName/GPG_Variable_Refrigerant_Flow_12-2012.action
4 – http://www.seedengr.com/Variable%20Refrigerant%20Flow%20Systems.pdf
5 – http://www.achrnews.com/articles/133074-infographic-vrf-gaining-ground-in-us
6 – http://www.achrnews.com/articles/133041-hvac-industry-embracing-vrf-solutions
7 – http://www.achrnews.com/articles/133683-vrf-making-inroads-in-hospital-intensive-care-markets
8 – https://www.green-buildings.com/articles/variant-refrigerant-flow-ready-for-primetime/
9 – http://www.facilitiesnet.com/hvac/tip/Variable-refrigerant-Flow-VRF-Systems-Weighing-Benefits-And-Limitations–31505
10 – http://www.sciencedirect.com/science/article/pii/S2090447917300023
11 – https://www.green-buildings.com/articles/variant-refrigerant-flow-ready-for-primetime/
12 – https://www.bls.gov/ooh/installation-maintenance-and-repair/heating-air-conditioning-and-refrigeration-mechanics-and-installers.htm#tab-6