New Year, New Refrigerants for HVAC Systems

HVAC units and systems in the United States are getting a reboot with old refrigerants like the R-410A making way for the new. R-410A has served the HVAC industry well so far but it has one problem that increasingly cannot be overlooked: high global warming potential (GWP). Not only do these refrigerants have a strong ability to trap heat, which contributes to warming, they also have long lifetimes, which increases the potential for climate damage.

A new class of refrigerants called A2Ls—A = non-toxic, 2 = flammable, L = low burning velocity—will address their predecessors’ GWP. Standard 34 from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) classifies the A2Ls as a class of refrigerants “that have lower toxicity and flammability (flame propagation speed is less than 10 cm/s) compared to other classifications, making it the second-safest refrigerant category.”

R–32, R–452B, R–454A, R–454B, R–454C and R–457A all fall under the A2L umbrella.
 

History and regulations

The Montreal Protocol required the phasing out of the production of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants in the United States. The Kigali Amendment to the Montreal Protocol expanded the list of regulated substances to include hydrofluorocarbons (HFCs) with a view to reducing HFC usage to 15 percent of baseline levels by 2036. Because the A2L refrigerants have a significantly lower global warming potential than A1-class HFCs, their phased use is a key part of the HFC reduction plan.

The American Innovation and Manufacturing Act of 2020 borrows a page from the Kigali Amendment and allocates quotas to producers of fluorinated refrigerants. These quotas follow a phased reduction schedule and are based on the refrigerants’ GWP.

The U.S. Environmental Protection Agency has set specific dates for the transition to A2Ls. The National Association of Home Builders lays out how the changes will affect residential units: “Residential and light commercial air conditioners and heat pumps manufactured after Jan. 1, 2025, must use the new refrigerant. The equipment manufactured prior to this date has a one-year grace period to be installed. For products that do not require field assembly, such as window air conditioning units, the rules establish the final date of sale as three years after the manufacture compliance date—a Jan. 1, 2028, sale deadline—without a compliance date for installation.”

The rules differentiate between HVAC products and systems. An HVAC product is a self-contained entity like air conditioning units while a system is a group of components assembled and charged for HVAC functions.
 

A different concern

While the A2Ls have lower GWP than their predecessors, they are mildly flammable, which means building codes need to factor this difference in design. One of the primary ways to do so is by installing leak detection protocols that become increasingly stringent depending on the amount of A2L refrigerant used.

These amounts are codified as M1, M2, and M3 classifications, each of which is a signifier for the amount of refrigerant—and therefore, the potential for leakage—in a system. The M1 level doesn’t require significant mitigation. Most residential equipment fall above the M1 limit, which means they require the first level of mitigation, said Clifton Beck, manager of digital media at ESCO Institute, which offers training and learning solutions for HVACR professionals. Equipment and products above the M1 level will need a means to detect leakage of refrigerants. 

Out in the field, Beck is seeing more manufacturers of HVAC equipment getting prepared for the switchover and releasing new models accordingly. “Contractors have been installing residential split systems with complete success,” Beck said. “It’s really just a matter of training the industry for the differences.”
 
ESCO offers online training as well as books and curricula devoted specifically for low GWP safety.

Architects like Jeremy Baldwin, multifamily studio lead at Maugel DeStefano Architects, have also been getting ready for the switchover and how it might affect designs. “A2L refrigerants required additional fire-rated construction for shafts that contain refrigerant lines if they penetrate multiple floors,” Baldwin said. “Designs now include increased ventilation, either mechanical or natural. 

“Internally, we’re updating design protocols and running project-specific evaluations to proactively integrate these changes. This includes considering design elements like ventilation needs for rated shafts to safely handle A2L refrigerants, as well as potential adjustments in project timelines and budgets to accommodate these changes,” Baldwin added.

The new containment and safety mechanisms will likely influence equipment placement, size, and even the way mechanical rooms are configured, Baldwin said. 

The new HVAC standards apply primarily to new projects or major renovations. “However, owners of existing buildings using R-410A should be aware that this refrigerant will eventually be phased out, and replacement parts will become scarce. While existing systems don’t have to be retrofitted immediately, we are advising clients on the potential long-term costs and encouraging them to plan for future upgrades to comply with the new standards,” Baldwin said. 

Globally, A2Ls have been used safely for years, Beck pointed out. Until recently, the United States had not been ready for a mildly flammable refrigerant, he added. But we’re ready now.

Poormima Apte is a technology writer in Walpole, Mass.