R-454B vs R-32

What changes in the field

These are the two refrigerants US manufacturers moved to when R-410A left new residential equipment. R-454B is a blend of R-32 and R-1234yf. R-32 is the pure fluid. Both are ASHRAE class A2L, so the handling rules are the same: A2L-rated recovery machines (40 CFR 82.158 Appendix B4, UL 1963 Supplement SB), A2L-rated service equipment as OEMs require, red-banded RAL 7044 cylinders, and often left-hand thread valves. The A2L refrigerants guide covers the site and brazing side.

Pressures differ more than the R-410A heritage suggests. From the PT data, R-32 dew pressure at 40°F is 13.5 psi above R-454B. At 100°F condensing, R-32 bubble is 325.7 psig and R-454B is 303.3 psig, 22.4 psi apart. R-454B sits below R-410A and R-32 sits slightly above it.

Glide is the other field difference. R-454B is a zeotrope with about 2.7°F of glide at 40°F evaporating. Read dew for superheat and bubble for subcooling. R-32 has zero glide, so there is one column. R-454B is charged as liquid. R-32 does not fractionate, though Danfoss still calls for a liquid initial charge.

Oil: Copeland lists POE for both. Carrier says R-454B equipment uses the POE or PVE lubricant the manufacturer specifies.

Retrofit or replacement

Neither one goes into the other’s system. Each piece of equipment is listed under UL 60335-2-40 for a specific refrigerant, with charge limits and, where required, leak detection set around that refrigerant’s properties. Carrier states that “equipment components, controls and safety requirements are designed around the specified refrigerant” and tells technicians to use the manufacturer’s specified pressures, charging procedure and service documentation. The metering device and controls are tuned for one pressure curve, and the gap in the table above is big enough to matter.

When you replace a system, choose by brand and model line rather than by refrigerant. Parts, service cylinders and the OEM’s charging charts follow the brand. For the three-way view including R-410A, see What replaces R-410A.

Capacity, efficiency and cost

Arkema, an R-32 supplier, claims R-32 has “higher capacity and better efficiency over R-410A” and allows a smaller charge. It gives no number and no comparison against R-454B. Carrier’s R-454B page gives no efficiency comparison either. No percentage is quoted here. Compare AHRI ratings of the actual systems.

GWP on the AR4 basis is 466 for R-454B and 675 for R-32 (EPA’s 40 CFR 84.64 calculation gives R-454B 465). Both are under the 700 limit for new residential and light commercial AC and heat pumps. On cost, the only sourced point is that the 2026 final rule preamble (91 FR 31284) discusses R-454B service-cylinder supply shortages.

Common questions

Which is more flammable, R-454B or R-32?

Both carry the same ASHRAE 34 class, 2L, which means low burning velocity (10 cm/s or less) and an LFL above 0.10 kg/m³. Charge limits for each come from UL 60335-2-40 and the equipment listing, not from a field judgment. See flammability safety classes.

R-454B vs R-32: which is better?

Neither is better for a system designed for the other. R-454B has the lower GWP but has glide. R-32 is a single component with no glide, which makes recovery and recharge simpler. The equipment you install decides which one you service.

Can you mix R-454B and R-32?

No. A mixture is neither refrigerant and matches neither PT chart. Recover each into its own cylinder.