A2L Refrigerant Transition
R-454B vs R-410A
The head-to-head for the A2L transition: global warming potential, safety class, operating pressure, and the questions techs actually ask - is it a drop-in, and can you reuse the line set.
R-454B vs R-410A Comparison Chart
| Property | R-454B | R-410A |
|---|---|---|
| Safety class (ASHRAE 34) | A2L (mildly flammable) | A1 (nonflammable) |
| GWP (100-yr, AR4) | 465 | 2,088 |
| GWP vs R-410A | 78% lower | baseline |
| Composition | R-32 / R-1234yf (68.9 / 31.1%) | R-32 / R-125 (50 / 50%) |
| Temperature glide | ~1.5°F | Near-zero (near-azeotropic) |
| Pressure at 40°F | ~112 psig | ~118 psig |
| Pressure at 100°F | ~301 psig | ~317 psig |
| Oil | POE | POE |
| Status | Primary replacement (new equipment 2025+) | Outgoing standard (2010-2025) |
| Retrofit into R-410A equipment | No – needs A2L-listed equipment | — |
GWP on the AR4 basis EPA uses. Pressures are saturation (bubble) pressures at the stated temperature. R-454B glide is small (~1.5°F); R-410A is near-azeotropic.
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What the Switch Means in the Field
- New equipment, not a recharge. R-454B goes into A2L-listed systems (leak detection, revised components per UL 60335-2-40). You will not service an existing R-410A unit with it.
- The line set reuses - no oil flush. R-410A and R-454B both run POE oil, so a copper line set left from an R-410A system does not need a chemical flush for oil compatibility. Pressure-test, evacuate, verify sizing, and follow the manufacturer’s instructions.
- Pressures and readings are close. R-454B sits a few percent below R-410A on pressure, so gauges and charging feel familiar. Use the R-454B PT chart, not R-410A’s, and remember the small glide when reading superheat and subcooling.
- It is a mild A2L, not propane. A2L means lower toxicity and low burning velocity - far less flammable than A3 refrigerants - but it still requires A2L handling, leak detection, and charge-limit rules.
Frequently Asked Questions
Is R-454B a drop-in replacement for R-410A?
No. R-454B is classified A2L (mildly flammable) and requires equipment designed and listed for A2L refrigerants, with leak detection and revised components per UL 60335-2-40 and ASHRAE 15.2. You cannot simply add R-454B to an existing R-410A system; it goes into new A2L-rated equipment, which is what manufacturers ship for AC and heat pumps built from January 1, 2025.
Can I reuse the R-410A line set with R-454B?
Usually yes. Both R-410A and R-454B use POE (polyol ester) oil, so replacing an R-410A system with an R-454B system does not require an oil flush of the existing copper line set. The line set should still be pressure-tested, evacuated, and confirmed clean and correctly sized for the new equipment, and you must always follow the equipment manufacturer's instructions, but the same POE oil on both sides means no chemical flush for oil compatibility.
What is the GWP difference between R-454B and R-410A?
R-454B has a GWP of 465 versus R-410A's 2,088 on the AR4 basis EPA uses, roughly 78% lower. That reduction is the entire reason for the transition: the EPA Technology Transitions rule caps new residential and light-commercial AC and heat pump refrigerants at a GWP of 700, which R-410A exceeds and R-454B meets.
Does R-454B run at a lower pressure than R-410A?
Slightly lower. At a 40°F saturation temperature R-454B is about 112 psig versus about 118 psig for R-410A, and at 100°F about 301 versus 317 psig. The two are close enough that system components are similar, but R-454B's pressures run a few percent below R-410A across the range. R-454B has a small temperature glide of about 1.5°F, while R-410A is near-azeotropic (near-zero glide).
What refrigerant is replacing R-410A?
R-454B and R-32 are the primary A2L replacements. R-454B (sold as Carrier's Puron Advance) leads in ducted residential and light-commercial systems from Carrier, Trane, and York; R-32 leads in mini-splits and Daikin/Goodman unitary equipment. Both are A2L with far lower GWP than R-410A.
Are R-454B and R-410A the same composition?
No. R-410A is a 50/50 blend of R-32 and R-125. R-454B is a blend of R-32 (68.9%) and R-1234yf (31.1%), an HFO. Replacing the high-GWP R-125 with low-GWP R-1234yf is what drops R-454B's GWP from 2,088 to 465.