Heat pump refrigerants: R-410A, R-32 and R-454B

As of October 2026, new residential air conditioners and heat pumps in the U.S. must use a refrigerant with a global warming potential (GWP) below 700. The limit started January 1, 2025, under EPA's Technology Transitions rule.^{[Source 1][Source 2]} Most new residential heat pumps now use R-32 or R-454B in place of R-410A. Existing R-410A systems can keep running and be repaired.^{[Source 3]}

The three refrigerants

Refrigerant	GWP (EPA reference table)	GWP (EPA SNAP page)	ASHRAE safety class listed by EPA
R-410A	2,088	2,090	not A2L
R-32 (HFC-32)	675	675	A2L
R-454B	465	470	A2L

GWP values are from EPA's Technology Transitions GWP Reference Table^{[Source 4]} and EPA's SNAP page for residential air conditioning and heat pumps.^{[Source 5]} The two EPA pages round differently, so the numbers for R-410A and R-454B differ slightly between them. EPA's SNAP page lists R-32 and R-454B with the A2L safety classification.^{[Source 5]}

GWP compares how much heat a gas traps relative to carbon dioxide over a set period.

What A2L means

The A2L label comes from the ASHRAE Standard 34 safety classification. "A" is the lower-toxicity class. EPA training material explains the flammability classes: class 1 shows no flame propagation in the test, and flammable refrigerants are graded as 2L (lower flammability), 2 (flammable) and 3 (higher flammability).^{[Source 6]} R-32 and R-454B are 2L. EPA's comparison shows a 2L refrigerant with a burning velocity of 1.6 cm/s against 46 cm/s for a class 3 refrigerant.^{[Source 6]}

EPA lists R-454B as "acceptable with use conditions," which refers to the safety conditions in the rule that listed it.^{[Source 5]} The installation manual for an A2L system sets out the requirements the installer must follow for that model.

The rule timeline, as of October 2026

EPA's rule history:^{[Source 1]}

Date	Action
October 24, 2023	Final Technology Transitions rule sets a GWP limit of 700 for residential and light commercial AC and heat pumps, starting January 1, 2025
December 26, 2023	Interim final rule lets equipment manufactured or imported before January 1, 2025 be installed until January 1, 2026
December 12, 2024	Rule extends installation dates for variable refrigerant flow (VRF) systems; does not change residential split systems
October 3, 2025	EPA proposes a reconsideration of parts of the rule
May 26, 2026	Final rule, effective July 27, 2026, removes the January 1, 2026 installation deadline for systems whose components were made or imported before January 1, 2025

EPA's fact sheet for the May 2026 rule says it "removes the January 1, 2026, installation compliance date" and allows pre-2025 inventory to be installed "until supply runs out."^{[Source 1]} EPA's sector page now says there is "no installation compliance date for systems where all specified components were manufactured or imported prior to January 1, 2025."^{[Source 2]}

Note on conflicting EPA pages. EPA's Frequent Questions page, last updated September 14, 2026, still says that "after January 1, 2026, if a whole new system is installed it must use lower-GWP refrigerant."^{[Source 3]} That conflicts with the May 2026 rule and the sector page. The rule and the sector page are the more specific and more recent statements.

Many websites and older articles still state the January 1, 2026 installation deadline. It was removed.

If you have an R-410A system

EPA's Frequent Questions page says homeowners "can maintain and repair their systems throughout the useful life," including replacing "a faulty component (e.g., condensing unit, indoor coil...) with a similar R-410A component."^{[Source 3]} R-410A replacement components made after January 1, 2025 must be labeled "for servicing existing equipment only."^{[Source 3]} EPA also notes that "the availability of HFCs and components may lessen over time as HFCs are phased down."^{[Source 3]}

Refrigerant handling of any kind requires an EPA Section 608 certified technician.^{[Source 8]}

The HFC phasedown

Separately from the equipment rule, the AIM Act reduces how much HFC refrigerant can be produced and imported. The schedule in federal regulation, as a share of the baseline:^{[Source 7]}

Years	Allowed share of baseline
2024 to 2028	60%
2029 to 2033	30%
2034 to 2035	20%
2036 onward	15%

EPA notes that the availability of HFCs may lessen as the phasedown proceeds.^{[Source 3]}

What to check when buying

• The refrigerant listed on the outdoor unit's nameplate and in the quote.
• For a partial replacement (outdoor unit only, or indoor coil only) on an R-410A system, ask whether the new component is an R-410A service part matched to the existing equipment.
• For a new system, ask for the AHRI certificate, which shows the certified combination of outdoor and indoor units.
• See Heat pump buying checklist.