HFCs, hydrofluoroolefins (hydrogen, fluorine and carbon, or HFOs), and blends of HFCs and HFOs can all be A2L refrigerants. A2Ls have a lower GWP and can cool more efficiently, requiring fewer refills.
ASHRAE Standard 34 categorizes the subgroup by their lower toxicity, burning velocity and flammability compared to other groups, but A2L refrigerants are slightly more flammable than the HFCs they are replacing.
| Higher Flammability | A3 (Propane, Butane) |
| Flammable | A2 (Methylene Fluoride) |
| Lower Flammability | A2L (R-454B, R-32) |
| No Flame Propagation at 140°F | A1 (R-410A) |
R-410A is an A1 refrigerant with a GWP above 2,000. R-410A products aren’t compatible with A2L products. While several A2L refrigerants are a close match for 410A’s capacity, there is no standard refrigerant that will replace them across the board.
R-32 (GWP of 675) and R-454B (GWP of 466) will be the predominant A2L refrigerants that manufacturers will use to replace R-410A, although there may be others in self-contained products.
In addition, A2L cylinders will have several key differences from those in the market today:
- They have left-hand threading, so adapters will be needed for compatibility.
- Tanks are gray with a red band on top.
- For safety, cylinders have pressure release valves instead of rupture discs.