R-454B vs R-32: The New AC Refrigerants

• Why R-410A is being replaced: global warming potential, or GWP. EPA's SNAP page shows a GWP of 470 for R-454B and 675 for R-32. R-410A's own figure is higher than either, which is the reason for the change.
• What A2L means: a safety classification for lower flammability. Lower flammability is not the same as non-flammable.
• Where these refrigerants can be used: only in new equipment, which can be specifically designed for the refrigerant, and equipment that meets a specific UL safety standard.
• Who uses which: Amana, Daikin and Goodman are listed with R-32. American Standard, Bryant, Carrier, Lennox, Mitsubishi Electric, Rheem and Trane are listed with R-454B. Ruud and York are listed with both R-410A and R-454B.
• What to do with that: compare complete systems, with model numbers, sizing and a plan for how the installation will be verified. The refrigerant name alone does not tell you which quote describes the better system.

What GWP measures

Refrigerant is the working fluid in an air conditioner or heat pump. It circulates in a sealed loop. In cooling mode it picks up heat from indoor air in one coil and releases that heat outdoors through the other coil, and a heat pump can run the same loop in reverse to heat the home.

Global warming potential is a number that compares how strongly a gas traps heat in the atmosphere with how strongly carbon dioxide does. The higher the number, the greater the warming effect for each unit of gas that escapes.

In a healthy system the refrigerant stays inside the sealed loop, so GWP matters most when refrigerant gets out: through a leak, through damage to the equipment, or because it was not recovered when equipment was taken out of service. That is why the choice of refrigerant is treated as an environmental question as well as an engineering one.

Why that points away from R-410A

R-410A is an HFC refrigerant blend that has been used in residential air conditioners and heat pumps for years. Its GWP is higher than that of the refrigerants now replacing it, and that difference is the reason for the change. This page does not give R-410A's own figure or any dates that apply to R-410A equipment, because the sources behind it do not cover them. A contractor, or EPA's own pages, is the place to confirm those.

How R-454B and R-32 compare on GWP

EPA's SNAP page lists R-454B, under the trade name Opteon XL41, with a GWP of 470. The same page lists HFC-32, which is R-32, with a GWP of 675. By EPA's figures, R-454B has the lower GWP of the two.

On GWP alone, a lower number means less warming effect for each unit released. It does not by itself make one system a better fit for your home, and it is only one of the points in the comparison below. This page uses EPA's figures. If a manufacturer brochure shows a different number, ask which source it uses.

Reading the classification

A2L is a safety group classification from ANSI/ASHRAE Standard 34-2019. EPA states that all six refrigerants listed in its May 6, 2021 rule for residential and light commercial AC and heat pumps (R-32, R-452B, R-454A, R-454B, R-454C and R-457A) are classified A2L. EPA describes R-32 and the five blends as having lower flammability.

To read the code: the letter A marks the lower-toxicity group, and 2L marks the lower-flammability class. R-410A sits in the non-flammable class, A1, so A2L is a change in what is circulating inside the equipment, even though it is the lower-flammability tier of the flammable classes.

Lower flammability is not the same as non-flammable, and EPA's rule treats it that way. It requires warnings and markings on the equipment to inform consumers and technicians of potential flammability hazards. Because the rule requires those markings, you can ask your installer to show you where they are on the unit.

The safety standard behind the listing

The standard EPA points to is UL 60335-2-40. EPA's use conditions require these refrigerants to be used only in AC equipment, both self-contained equipment and split systems, that meets all requirements of the 3rd edition of the standard, dated November 1, 2019. EPA incorporated that edition by reference. The standard sets requirements for evaluating electrical air conditioners, heat pumps and dehumidifiers and for the safe use of flammable refrigerants.

A split system has an outdoor unit and an indoor unit joined by refrigerant lines, which is the usual layout for central air conditioning. EPA notes that the standard includes specific requirements for split-system appliances using A2L refrigerants, covering construction, instruction manuals, allowable charge sizes, mechanical ventilation and safety alarms. For variable refrigerant flow (VRF) systems, which serve several indoor units from one outdoor unit, the standard also covers shut-off valves.

Whether a particular model relies on any of those features is a question for that model's documentation. This page does not state which ones apply to which equipment.

The use conditions in plain language

EPA's use conditions for these refrigerants come down to three requirements.

• The refrigerant goes only into new equipment, which can be specifically designed for it.
• Its use must be consistent with UL 60335-2-40, including testing, charge sizes, ventilation, usage space requirements and certain hazard warnings and markings.
• The equipment must carry warnings and markings that tell consumers and technicians about potential flammability hazards.

"Acceptable, subject to use conditions" is EPA's wording. It means the refrigerant is allowed when those conditions are met. In everyday terms, the second item is about how the equipment is tested, how much refrigerant it holds and the space around it. The standard itself is where the exact limits are written, and this page does not state any.

EPA's final rule listing both refrigerants was published May 6, 2021 and took effect June 7, 2021. The table shows what EPA and the equipment-line data say about each.

What the table shows

The safety class does not separate them. Both are A2L, so the classification is the same whichever quote you pick.

GWP does. By EPA's figures R-454B is lower than R-32.

One is a blend and one is not. EPA counts R-454B among five refrigerant blends and treats R-32 separately. A blend is a mixture of two or more refrigerants, and R-32 is a single refrigerant.

The listing histories differ. EPA's page shows one rule date for R-454B and three for HFC-32. The page does not say what the 2015 and 2023 rules did, so this page does not either.

R-32's May 2021 listing has an exclusion. It covers new equipment other than self-contained room air conditioners. That exclusion does not apply to a split-system central AC or heat pump, which is what most homeowners comparing quotes are looking at.

Which brands list which refrigerant

In the equipment-line data behind this page, the brands fall into three groups.

• Listed with R-32: Amana, Daikin and Goodman.
• Listed with R-454B: American Standard, Bryant, Carrier, Lennox, Mitsubishi Electric, Rheem and Trane.
• Listed with both R-410A and R-454B: Ruud and York.

Three cautions go with that list. A brand appearing here means the data lists that refrigerant for the brand's equipment lines. It does not say every model from the brand uses it. The data gives no model names or years, so this page cannot say which products carry which refrigerant, or since when. And for Ruud and York, which appear with two refrigerants, the model number on the quote is what tells you which refrigerant you would be getting.

Blume is brand-agnostic: as a licensed contractor it sells, installs and services all major manufacturers. So this list is information, not a recommendation of any brand.

What the comparison does not settle

Nothing in the EPA record compares R-454B and R-32 on efficiency, comfort, noise or reliability, so this page makes no claim either way. Efficiency is rated model by model. The manufacturer publishes a SEER2 rating for cooling for a given outdoor-and-indoor combination, and ENERGY STAR publishes its own listings of qualifying models. The refrigerant name alone does not tell you the rating, so ask for the rating of the exact combination on the quote.

New equipment, designed for the refrigerant

EPA's use conditions limit these refrigerants to new equipment that can be specifically designed for them. The listings do not provide for converting an existing R-410A system by swapping the refrigerant. If a proposal does that, ask the contractor to show the manufacturer documentation that allows it.

Match the whole system

The use condition covers both self-contained equipment and split systems. In a split system the outdoor unit and the indoor coil or air handler work as a pair, and the safety standard has specific requirements for split-system appliances. A quote should name both halves with model numbers, not only the outdoor unit.

Installation

Every refrigerant system depends on a sound installation: clean, leak-tight refrigerant lines, correct airflow across the coil, and a refrigerant charge set to the manufacturer's specification. None of that is new with A2L refrigerants.

What the A2L standard adds is a set of topics the installer has to work through: allowable charge sizes, mechanical ventilation and safety alarms are among the subjects EPA names in the standard, and the standard sets requirements for the instruction manuals. The installation instructions for the specific model are where to look for how those topics apply, and a good installer works from them.

Service and repair

Whichever refrigerant is on the nameplate, the refrigerant added to a system has to match it. Refrigerants are not mixed or substituted. A technician working on a system with an A2L refrigerant should work from that model's instructions and warnings, treat ignition sources in the work area with care, and use tools and recovery equipment suited to the refrigerant. If you are choosing a contractor to service a system with either refrigerant, ask whether their technicians work on A2L equipment.

Because the equipment is required to carry warnings and markings, a technician or a homeowner can see at a glance what the unit contains.

Your current R-410A system

The EPA listings behind this page are about new equipment. They say nothing about R-410A systems already installed. Whether to repair or replace an older system is a separate decision that depends on the unit's condition and on what the repair involves.

What may still change

On November 10, 2025, EPA proposed to update the existing use conditions for HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290 and R-441A in residential and light commercial AC and heat pumps. Comments were due December 26, 2025. The proposal includes incorporating the 4th edition of UL 60335-2-40, dated December 15, 2022.

In that proposal EPA states that the 3rd edition, which the current regulations incorporate, is no longer the latest edition applicable to this end use. EPA says the 4th edition sets more comprehensive requirements on A2L refrigerants, and proposes to consider its additional safety mechanisms, including charge size limitations, more protective of human health and the environment.

The same proposal would also list two more refrigerants, R-516A and HFO-1234ze(E), as acceptable subject to use conditions for all applications in this end use.

No final rule was found at the time this page's evidence was gathered, so everything in this section is a proposal, not a requirement. For a homeowner the practical step is to ask which edition of the standard the quoted equipment was evaluated to, and whether the manufacturer's documentation says so. Check EPA's SNAP pages for the current status before relying on this section.

1. Get the refrigerant and the full model numbers in writing. That means the outdoor unit and the indoor coil or air handler. For Ruud and York in particular, the model number settles which refrigerant is quoted.
2. Confirm it is a new system designed for that refrigerant, not a conversion. EPA's use conditions are written for new equipment. Ask to be shown where the warnings and markings are on the equipment.
3. Ask which safety standard and edition the equipment was evaluated to. The current EPA rule incorporates the 3rd edition of UL 60335-2-40, and a 4th edition is in a proposal. The manufacturer's documentation is where this should be stated.
4. Ask how the equipment was sized. A load calculation is a different thing from swapping a unit for the same size as the old one.
5. Ask how the installation will be verified. Measured static pressure, measured airflow and a measured refrigerant charge, written down, are what you want to see.
6. Compare efficiency ratings for the exact combinations, not for the refrigerant names.
7. Put the same questions to both contractors. If one quote answers and the other does not, that tells you something that the refrigerant name does not.

Blume Mechanical Service, LLC is a Class A licensed Florida mechanical contractor, license CAC-1822618 (authority: Florida DBPR), fully insured, working on residential and commercial systems from Belleair Bluffs and serving Pinellas, Hillsborough and Pasco counties. Its refrigerant work is done by EPA Section 608 certified technicians, who hold the federal refrigerant-handling credential.

Blume sizes equipment with an ACCA Manual J load calculation and Manual S selection, not rule-of-thumb swaps. It commissions systems with measured static pressure, airflow and refrigerant charge, documented. It lays out repair and replacement options side by side, and does not sell equipment a building does not need.

Those are the same questions the checklist above asks of any contractor.