Awaiting expert review. This page covers safety or regulatory rules that change over time. It is kept out of search results until a qualified reviewer has checked it; the sources below are dated so you can verify each point.
Quick answer
R-454B is a refrigerant blend of about 69% R-32 and 31% R-1234yf by weight that replaces R-410A in many new US air conditioners and heat pumps, with a global warming potential of 465 on EPA's table and a mildly flammable A2L safety class.
It is sold under trade names such as Opteon XL41. EPA lists it as acceptable only in new equipment designed for it, under use conditions that include UL 60335-2-40.
Quick facts
The key facts about R-454B Refrigerant, with sources:
- Composition
- R-32 / R-1234yf, 68.9 / 31.1 % by weight 1
- GWP (EPA reference table)
- 465 2
- GWP (maker, IPCC AR4 / AR5)
- 466 / 467 1
- Safety class
- A2L (lower toxicity, lower flammability) 1
- Burning velocity
- 5.2 cm/s at 23°C 1
- Temperature glide
- About 1.5 K 1
- EPA SNAP status
- Acceptable subject to use conditions, new residential and light commercial AC/HP only (effective 7 June 2021) 3
Key takeaways
- R-454B is a lower-GWP replacement for R-410A in new equipment, not a drop-in for old systems 3.
- EPA's table lists its GWP at 465, under the 700 limit for new residential systems 2 5.
- It is A2L: mildly flammable, so equipment carries labels, charge limits and often leak sensors 3.
- Its small glide (about 1.5 K) matters for charging and gauges 1.
- Only EPA 608 certified technicians trained for flammable refrigerants should service it 6 3.
What R-454B is
R-454B is a blend of two chemicals: R-32 (difluoromethane), an HFC, and R-1234yf, an HFO with a GWP of 1 on EPA's table 2. Chemours gives the mix as 68.9% R-32 and 31.1% R-1234yf by weight 1. Adding the HFO lowers the blend's GWP below that of R-32 alone.
Chemours describes it as a close match to R-410A for equipment designers, with improved capacity and efficiency in its cycle calculations 1. That made it a common choice for US makers moving ducted splits, packaged units and mini-splits off R-410A for 2025.
It is an A2L refrigerant: "A" for lower toxicity, "2L" for lower flammability. Chemours calls it non-toxic and mildly flammable, with a burning velocity of 5.2 cm/s 1.
How R-454B changes an installation, step by step
- Equipment designed and labeled for R-454B → flammable refrigerant warnings on the units 3
- Indoor unit plate → minimum room area (and sometimes minimum install height) per UL 60335-2-40 3
- Charge ≤ the maximum allowed for the room size 3
- Many systems → refrigerant detection sensor that stops the compressor and runs the blower if a leak is found
- Service → trained technicians, spark-proof tools, recovery equipment designed for flammable refrigerants 3
How R-454B behaves in a system
R-454B runs the same refrigeration cycle as R-410A at slightly lower pressures. In Chemours' theoretical comparison, suction pressure ran 30 to 65 kPa lower and discharge pressure 140 to 229 kPa lower than R-410A, mass flow about 20% lower, and discharge temperature 5.4 to 12.6 K higher 1.
Because it is a blend, it has a temperature glide of about 1.5 K: it boils and condenses over a small range rather than one point.
Chemours notes the glide is low enough that systems can be topped off after leaks 1. Gauges must be set to R-454B, and charging follows the maker's superheat or subcooling targets.
Chemours lists it as miscible with POE lubricants 1.
Sources: [1]
R-454B properties at a glance
| Property | Value | Source |
|---|---|---|
| Composition | R-32 / R-1234yf, 68.9 / 31.1 wt % | 1 |
| Molecular weight | 62.6 g/mol | 1 |
| Boiling point at 1 atm | −50.6°F (−50.9°C) | 1 |
| Critical temperature | 170.6°F (77°C) | 1 |
| Ozone depletion potential | 0 | 1 |
| GWP, EPA Technology Transitions table | 465 | 2 |
| Lower flammability limit | 0.303 kg/m³ (worst-case formulation) | 1 |
| Burning velocity | 5.2 cm/s (2.0 in/s) at 23°C | 1 |
Worked example: why the GWP is 465, not 698
EPA's table calculates a blend's GWP from its parts. Using EPA's values for HFC-32 (675) and HFO-1234yf (1) and the Chemours composition 2 1:
| Step | Math | Result |
|---|---|---|
| R-32 share | 0.689 × 675 | 465.1 |
| R-1234yf share | 0.311 × 1 | 0.3 |
| Blend GWP | 465.1 + 0.3 | About 465, matching EPA's table |
| Common mix-up | R-452B, a different blend on the same table | 698 2 |
You may also see 466 or 467: those are the maker's figures on IPCC AR4 and AR5 values 1. The 698 sometimes quoted for R-454B is R-452B's figure. Either way, R-454B sits well under the 700 limit, and its GWP is about 78% lower than R-410A's 2,088 (465 ÷ 2,088 ≈ 0.22) 2.
Where you see R-454B
Pros and cons of R-454B
What it does well
What R-454B is not
It is not a drop-in. EPA's SNAP listing says R-454B may be used only in new equipment specifically designed and clearly identified for it; it may not be used as a conversion or retrofit refrigerant for existing equipment designed for other refrigerants 3.
It is not a free pass on room size. The charge must not exceed the maximum set by UL 60335-2-40 for the room where the equipment is used 3. Small rooms may need smaller units or leak detection and ventilation measures the maker specifies.
Sources: [3]
Cost drivers
Equipment cost depends more on the system than the refrigerant, but A2L systems can add parts such as refrigerant detection sensors and require compatible coils and line sets. Mixed old-and-new installs are not allowed, so an R-454B outdoor unit usually means a matching new indoor coil.
HyreHVAC does not print prices without enough local quotes; see the replacement calculator and our refrigerant transition research.
Installing an R-454B system (pro checklist)
- Confirm the indoor unit's minimum room area against the space it serves 3.
- Use a matched R-454B outdoor unit and coil.
- Use tools and recovery equipment rated for flammable refrigerants 3.
- Pressure test, evacuate and charge per the maker.
- Wire and test any refrigerant detection system.
- Confirm warning labels are in place and permanent 3.
Owner care
- Same as any AC: filters, a clean outdoor coil, open vents.
- Do not unplug or disable a refrigerant leak sensor; one R-32 manual says the leak detection system must stay powered except for service 7.
- Keep the indoor unit's space as designed; do not enclose it in a smaller closet, because the allowed charge was set for the room area on the plate.
- Tell any contractor doing remodel work near the equipment that it uses a flammable A2L refrigerant.
- Never attempt refrigerant work yourself 6.
Safety and warning signs
- If the system shuts down the compressor and runs the fan unexpectedly, the leak sensor may have tripped: ventilate and call a technician.
- If a leak is suspected indoors, open windows, avoid flames and sparks, and leave if you feel unwell.
- EPA's listing says room occupants should evacuate immediately after an accidental release 3.
- Liquid refrigerant can cause freeze burns 3.
Rules for R-454B (checked 10 October 2026)
EPA SNAP, 40 CFR Part 82 Subpart G, Appendix W (effective 7 June 2021). R-454B is acceptable subject to use conditions in new residential and light commercial AC and heat pumps: new equipment only, no retrofit.
Equipment must meet UL 60335-2-40 (3rd edition); charge limited by room size; permanent warning labels; minimum room area markings; trained technicians, spark-proof tools and recovery equipment designed for flammable refrigerants 3.
Proposed change. EPA's proposed SNAP Rule 27 (signed November 2025) would update these conditions to UL 60335-2-40 4th edition or require NRTL certification, for equipment made after a final rule takes effect. EPA's April 2026 fact sheet describes it as a proposal 4.
AIM Act. With a GWP of 465, R-454B meets the 700 limit in 40 CFR 84.54 for new residential and light commercial systems effective 1 January 2025 5.
Handling. Section 608 certification is required for service 6.
R-454B vs R-32 vs R-410A
| R-454B | R-32 | R-410A | |
|---|---|---|---|
| GWP (EPA table) | 465 | 675 | 2,088 |
| Type | Blend (R-32 + R-1234yf) | Single compound | HFC blend |
| Glide | About 1.5 K 1 | None (single compound) | Not covered here |
| Safety class | A2L 1 | A2L | Not A2L |
| New residential systems | Allowed with SNAP conditions | Allowed with SNAP conditions | Only pre-2025 component inventory |
Common misconceptions
- Myth R-454B has a GWP of 698.
- Reality EPA lists 465; 698 is R-452B 2.
- Myth R-454B can go into an R-410A system.
- Reality SNAP bars retrofits 3.
- Myth Mildly flammable means unsafe.
- Reality It means equipment must follow UL 60335-2-40 charge, labeling and handling rules 3.
- Myth R-454B cannot be topped off because it is a blend.
- Reality Chemours says its low glide allows topping off after leaks 1; the leak still must be fixed.
Local codes and A2L installs
Federal rules set the refrigerant limits; local building and fire codes decide how A2L equipment is installed. Adoption of A2L-ready code editions varies by state and city, and HyreHVAC has not verified each state's adoption status. Ask your installer and building department which code edition applies, especially for small rooms or closets.
When this matters to you
If you are buying a new system, R-454B and R-32 are the main choices. Compare the equipment, efficiency and installer, not just the refrigerant. If you already have R-454B, keep the leak sensor powered and use a technician trained on A2L refrigerants.
Next step: compare picks on our best heat pumps page.
Questions about R-454B Refrigerant
What is R-454B?
R-454B is a refrigerant blend of about 69% R-32 and 31% R-1234yf. It replaces R-410A in many new US air conditioners and heat pumps. EPA's table lists its GWP at 465, and it is a mildly flammable A2L refrigerant.
What is the GWP of R-454B?
EPA's Technology Transitions table lists 465. Chemours lists 466 on IPCC AR4 values and 467 on AR5. The 698 sometimes quoted belongs to a different blend, R-452B.
Is R-454B flammable?
It is classed A2L, meaning lower toxicity and lower flammability. Chemours lists a burning velocity of 5.2 cm/s. EPA allows it only in equipment that meets UL 60335-2-40, with charge limits, labels and trained technicians.
Can R-454B replace R-410A in my existing system?
No. EPA's SNAP listing allows R-454B only in new equipment designed for it, not as a retrofit refrigerant. A new R-454B outdoor unit needs a matching R-454B indoor coil.
Is R-454B better than R-410A?
For climate, yes: its GWP is about 78% lower. Chemours' cycle calculations show similar capacity and slightly higher COP than R-410A. Real performance depends on the equipment design.
What is the difference between R-454B and R-32?
R-32 is a single compound with a GWP of 675. R-454B blends R-32 with R-1234yf to reach a GWP of 465, and has a small glide. Both are A2L refrigerants used in new equipment.
Do R-454B systems need leak detectors?
Many do, depending on charge size and room size under UL 60335-2-40. When a sensor is fitted, the maker requires it to stay powered. It can stop the compressor and run the blower if it senses a leak.
Can R-454B be topped off after a leak?
Chemours says its low temperature glide allows topping off. The leak should still be found and repaired first, by a certified technician trained on flammable refrigerants.
Sources
- Chemours, Opteon XL41 (R-454B) Product Information (C-11001, 9/2016), retrieved .
- U.S. EPA, Technology Transitions GWP Reference Table (updated 2 April 2026), retrieved .
- eCFR, 40 CFR Part 82 Subpart G, Appendix W: SNAP substitutes listed in the 6 May 2021 final rule (effective 7 June 2021), retrieved .
- U.S. EPA, Fact Sheet: Proposed SNAP Rule 27 (April 2026), retrieved .
- eCFR, 40 CFR Part 84 Subpart B, §§ 84.52–84.56 (version of 1 September 2026), retrieved .
- U.S. EPA, Section 608 Technician Certification, retrieved .
- Goodman / ACiQ, A/GPHM3 13.4 SEER2 M-Series packaged heat pump with R-32, installation instructions (IOG-3035B, 2025), retrieved .
Expert review
Written by the HyreHVAC Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Held under G-REV. Properties copied from the Chemours Opteon XL41 product sheet; GWPs (R-454B, HFC-32, HFO-1234yf, R-452B, R-410A) from EPA's reference table.
Use conditions from the eCFR text of 40 CFR 82 Subpart G Appendix W; proposal status from EPA's April 2026 Rule 27 fact sheet; all read 10 October 2026.
The GWP arithmetic uses those published values only.
Suggest a correction. We fix errors and say what changed.