Six Challenges with Variable Refrigerant Flow Systems (VRF Systems)

While the technology has been available for approximately 30 years, Variable Refrigerant Flow Systems (VRF Systems) are starting to find their way into more North American HVAC Systems. Meanwhile many have found there are several problems with VRF Systems, often after installation.

Appealing because they operate on ductless technology, many building engineers have been led to believe that VRF Systems are a cost-effective way to heat and cool a building.

As nice as that sounds, many have found there are several problems with VRF Systems, often after installation. This is what led to the U.S. Army Corps of Engineers banning the technology from U.S. Air Force facilities and “strongly discouraging” use in Army buildings.

To help you better understand why the technology isn’t as beneficial as it may appear on the surface, we’ve identified the following six issues prevalent with VRF technology:

1. VRF systems pose health and safety risks: When there’s a leak in a refrigerant system, it can often be difficult to detect. This is because leaks typically can’t be seen or smelled, as they’re concealed sealed behind walls and out of sight.

While leaks can occur in both types of systems, a leak in a VRF System can be dangerous is in buildings with minimal ventilation. Here’s why: A commonly used refrigerant such as R-410a is heavier than air. When there’s a leak, the refrigerant will accumulate in lower portions of the rooms, with highest concentrations near the floor. Unbeknownst to building occupants, air is displaced and can cause someone to become unconscious and potentially lead to asphyxiation.

2. VRF systems aren’t flexible or adaptable: When you purchase a VRF system, you’re often locked into one manufacturer and their installer. Also, where components to hydronic systems are easily exchangeable and adaptable to changing energy demands and regulations, VRF systems must be used with other components within the manufacturer’s standard offering.

3. VRF systems have higher installation costs: Because they require specialized knowledge of how to solder unique fittings onsite, VRF system installers can charge more than most general contractors and installers. You’ll also a difference in material costs: When you compare the two systems side by side, the initial cost of a standard hydronic system can be up to 30 percent lower.

Another area where you can incur additional costs is add-on components such as refrigerant monitoring systems, proprietary controls and even longer refrigerant pipelines required to operate the system.

4. VRF doesn’t offer storage capabilities: Unlike their hydronic counterparts, VRF systems do not have the ability to store or buffer heat. While a VRF system might be able to recover heat from one zone and use it in another, hydronic systems can draw the chill or heat from a room and carry that energy back to the system for storage or recovery. This reduces overall energy consumption—and costs.

5. VRF systems consume more energy: As buildings look to reduce their energy consumption, VRF system can negate that effort. VRF systems can take as much as 50 percent of total HVAC electrical consumption and use 15 times more horsepower than water-based HVAC systems.

A popular study performed by the U.S. Department of Energy measured heating efficiency of VRF. They found that the amount of energy consumed by a VRF system was 43 percent greater than what was claimed by the system manufacturer in its marketing materials. This is likely due to the additional energy required to circulate the refrigerant through long distribution channels.

If you're interested in comparing the energy loads between the two systems, this article published in PM Engineer offers a good look at the energy efficiency of hydronic systems over VRF.

Another study conducted in 2013 by Oklahoma State University and Oak Ridge National Laboratory evaluated the relative performance of geothermal heat pumps versus VRF heating and cooling systems installed at the American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) international headquarters building in Atlanta. This study found that geothermal heat pumps use 44 percent less energy than VRF systems on an annual basis.

6. VRF Systems have a shorter lifespan and higher overall costs. Where hydronic systems can typically last anywhere from 20-25 years, VRF systems will need to be replaced within 10 to 15 years.

In addition, one needs to also consider costs associated with equipment as common types of refrigerants will be phased out due to increasing sustainability regulations. This will lead to the likely replacement of VRF technology to accommodate new refrigerants.

Hydronic technology is a preferable solution for engineers looking to reduce costs, improve sustainability and keep building occupants safe.

Looking for additional resources to help you understand the issues associated with VRF technology? Check out

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