Variable Refrigerant Flow (VRF)

We recently came across information regarding variable refrigerant flow (VRF) and wanted to share with you. The article, VRF Rejection, discusses safety, efficiency, energy costs, proprietary systems, case studies, updated standards and pointed out some misconceptions regarding VRF as well. Each section touched on important information for the HVAC industry.

The first section that is approached is safety. The safety requirements the US Environmental Protection Agency will begin to enforce on Jan. 1, 2019 which includes the monitoring and inspection requirements for leaks and disposal and sales of refrigerant. The article also cautions the phasing out of refrigerant (for environmental and personal safety issues) could be a costly expenditure on existing VRF installations as the entire system would need to be replaced. Regarding efficiency and energy costs the assertion is that VRF is not necessarily more efficient than hydronic or air systems and that the use of energy was substantially more than the other systems it was tested against. The last three sections touch upon making sure you are meeting all required standards and being aware that a lot of VRF systems cannot be upgraded to the latest version that meets the requirements of refrigerant technology and laws that change constantly. Their case studies on VRF conclude that there are many possible drawbacks to using this system but they do suggest that by asking the right questions and proper VRF design under the right circumstances could work.

The limitation we see with VRF is that these systems more often than not come with their own controls making it difficult to integrate and then unable to achieve the sequence of operation necessary. The controls contractor is then called in and is responsible for making the system work. The contractor is in a no-win situation and the end user is let down because optimized energy efficiency is unattainable.

As a strong and competent controls contractor, AME can assist with design and implementation from the beginning, providing greater energy efficiency and optimization with the potential use of VRF systems. AME believes a control package outside of the manufacturers onboard controls (especially on VRF, RTU’s, built up AHU’s) will allow for flexibility and tighter controls. We are confident that if we can get the engineers, architects and end users to consult with the controls contractors ahead of time, the expectations can be achieved and managed.

In summation, we are not saying that the VRF solution is wrong. We are saying that it may not always be right. In either case having the controls contractor involved should allow for greater understanding of design expectations, verification of sequence of operation capabilities and a collaborative solution with all of the stakeholders. This will ensure that the end user’s expectations are as close to realize as possible.