R-454B vs R-32

At a glance

Both are below the 700 GWP limit in EPA's Technology Transitions rule for new residential and light-commercial AC and heat pump systems; R-410A, at 2,088, is not. Carrier (as Puron Advance) and Lennox sell R-454B residential equipment, and Daikin, which builds R-32 equipment under the Daikin, Goodman and Amana brands, compares its R-32 heat pump with R-454B models from Carrier, Lennox, Trane and Rheem.

Operating pressures

Arkema sums it up: R-454B "was designed to closely match the pressure-temperature profile of R-410A", while R-32 "runs at higher pressures than R-410A". At a 40°F evaporator, R-454B reads 107.0 psig (dew point) and R-32 reads 121.0 psig. At a 110°F condensing temperature, R-454B reads 345.9 psig (bubble point) and R-32 reads 374.9 psig.

Those gaps are big enough to matter on a superheat check. An R-32 suction reading of 121.0 psig is a 40°F evaporator, but on an R-454B chart that pressure would read as a dew point of 46.4°F. Set the manifold to the refrigerant on the rating plate.

Glide and charging

R-454B is a near-azeotropic blend with a small glide, so its PT chart lists bubble and dew points; use dew for superheat and bubble for subcooling. R-32 is one compound with a single saturation temperature, so its chart has one column.

That difference shows up in charging. Arkema advises charging R-454B as liquid because it is a blend, while R-32 can go in as vapor or liquid. Daikin says an R-32 system can be topped off in either phase without any change in composition, and that topping off blends is generally not recommended. Chemours, which makes R-454B, says its glide is low enough that it can be topped off after leaks. Follow the equipment manufacturer's service instructions.

Efficiency and charge size claims

Arkema credits R-32 with higher efficiency, better cooling capacity and a smaller refrigerant charge, and credits R-454B with an easier transition from R-410A designs. Daikin's brochure lists a factory charge of 82.6 oz for one of its 3-ton R-32 heat pumps against 90 to 121.6 oz for four competitors' R-454B models. These are manufacturer comparisons of specific products; real differences depend on the equipment.

Safety and equipment

Arkema notes that both are A2L under ASHRAE 34, and Copeland describes A2L refrigerants as lower flammability, with a maximum burning velocity under 10 cm/s. EPA's SNAP listings for both require residential and light-commercial equipment to meet UL 60335-2-40, 3rd edition, and both use A2L cylinders with a red band and left-hand valve threads. AHRI's A2L best practices call for an A2L-rated vacuum pump and recovery tools rated for A2L refrigerants, and AHRI's task force adds leak detectors rated for A2L refrigerants. See A2L refrigerants.

Parts and oil

Components are matched to one refrigerant. Payne's installation instructions for an R-454B heat pump open with "For use with R-454B indoor units only." Daikin says its R-32 systems use POE or PVE oils formulated for R-32, while Honeywell's data sheet recommends POE for R-454B. Copeland notes that A2L refrigerants are only for use in compressors approved for them. AHRI's A2L best practices say to use only OEM-approved replacement parts, so order parts by the model number on the rating plate.

Not interchangeable

Neither refrigerant is a retrofit for R-410A systems, per Arkema and EPA's new-equipment-only listings, and they are not interchangeable with each other. Daikin's pressure-temperature chart notes say A2L refrigerants cannot be used to retrofit a different refrigerant into an existing system and to always use the refrigerant marked on the nameplate. Pressures, glide and oil differ between the two, as the sections above show.