What EPA's A2L Listing Means for R-454B and R-32
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At a glance
EPA's own SNAP listing marks R-454B and R-32 A2L and 'Acceptable with Use Conditions,' while R-410A and R-134a on the same table are A1. This guide sticks to what that listing itself says, not ASHRAE's own definition of the class.
On this page
Two of this site's five refrigerants carry a designation the other three don't. This guide covers only what EPA's own Significant New Alternatives Policy (SNAP) listing says about that designation — not what ASHRAE Standard 34 itself defines it to mean, since that standard is a paid document this site hasn't purchased and doesn't quote.
What EPA's own listing shows
EPA's SNAP program reviews each proposed refrigerant substitute and publishes a listing table for every sector, including the home and light-commercial cooling and heat-pump sector. That table carries a column for the ASHRAE safety classification, alongside GWP, the SNAP listing date, and a status. For HFC-32, the table reads A2L in that column, with GWP 675 and a status of "Acceptable with Use Conditions: See rules for detailed conditions." For R-454B, the same column also reads A2L, with GWP 470 and "Acceptable with Use Conditions: See rule for detailed conditions." Both entries were added to the listing on May 6, 2021; HFC-32 carries two other listing dates as well, April 10, 2015 (earlier) and April 28, 2023 (later).
This site quotes that designation only as EPA's own column value on its own table — never with ASHRAE's own criteria for what separates one safety class from another. What follows is what changed procedurally, on EPA's own listing, not a technical explanation of the class itself.
Which of our five refrigerants carry it
| Refrigerant | ASHRAE designation (EPA's listing) | Status on EPA's listing |
|---|---|---|
| R-32 | A2L | Acceptable with Use Conditions |
| R-454B | A2L | Acceptable with Use Conditions |
| R-410A | A1 | Acceptable |
| R-134a | A1 | Acceptable |
| R-22 | not a listed substitute | n/a |
R-410A and HFC-134a sit on the same EPA table as A1, not A2L. R-22 doesn't appear on this table at all — it's the refrigerant SNAP substitutes replace, not a substitute EPA lists here.
What actually changed for a technician
Both R-32 and R-454B carry EPA's "Acceptable with Use Conditions" status, not a plain "Acceptable." That phrase means EPA's listing itself doesn't state the refrigerant is unconditionally approved for the sector — it points to a separate Federal Register rule for the actual conditions. Nothing in this site's saved copy of the listing spells out what those conditions require on the job, so nothing here should be read as a substitute for reading that rule, the equipment's own installation instructions, or the refrigerant's SDS.
What this page doesn't cover
This page doesn't reproduce the Federal Register rule's use conditions, doesn't explain ASHRAE's own criteria for the A2L class, and gives no leak-rate figures. For the separate question of which leak-repair rule applies to a given appliance and refrigerant — a question the AIM Act's 2024 rule answers by refrigerant type and charge size, not by safety class — see refrigerant leak repair: which rule applies. For routing to the right pressure–temperature chart, see which PT chart do I need.