HFCs are not going away any time soon. I am sure you have all hear about the push to reduce or eliminate HFC refrigerants because of their global warming potential. This past weekend at Comfortech 2016 I sat in on a very informative session by Rob Yost on refrigerants. One big point was that low GWP replacement candidates for R410A are all rated at 2 or 2L for flammability. The reason is pretty straight forward. To be non-flammable a chemical must be relatively stable. However, that stability means it lasts longer in the atmosphere, which increases its global warming potential. In other words, low flammability and low global warming potential are somewhat opposites in terms of chemical properties.
The newest low GWP blends being developed are actually blends of both HFOs and HFCs. The highest pressure HFO developed at this time is very similar in pressure to 134a. Obviously that won’t replace 410A. However, mixing it with some higher pressure HFC refrigerants yields a much lower global warming potential than 410A at working pressures that are similar to 410A. However, this mixture will be flammable.
The current building codes in the US don’t allow flammable refrigerants inside buildings in most circumstances, so none of the refrigerants presently being studied can be used under the current building codes. The next revision for building codes is due out in 2018. However, the window for incorporating exceptions for lower flammability refrigerants into the 2018 code has already passed – and no exceptions or conditions for the use of 2L flammable refrigerants are in the upcoming 2018 code. That makes 2021 the closest date that flammable refrigerants could possibly be used inside buildings. Even though that is only a little over four years from now, we can be reasonably sure that no mass extinction of HFC refrigerants will occur any time soon.
Before we transition out of 410A to something else, the issue of using lower flammability refrigerants inside buildings will have to be addressed, and even then, it is likely that HFC refrigerants will be some of the components in the next generation of refrigerants.