The short answer
R32 is the refrigerant in most new wall-mounted systems. It carries heat efficiently, usually needs less of it than R410A, and has about a third of R410A's global warming potential. It is mildly flammable, so it's handled with specific precautions.
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R32, also called difluoromethane, is the refrigerant in most new wall-mounted air conditioners for homes. It took over from R410A, which was the usual choice for many years. Knowing a little about it helps when you read a specification sheet, and explains why engineers treat it the way they do.
What R32 is
R32 is a single substance, not a blend. Blends such as R410A have to be handled so their mixture stays correct, for example by charging them into a system as a liquid. R32 doesn't have that concern, which makes it simpler to charge, recover and reuse.
R410A is itself a blend of R32 and another refrigerant, R125. Using R32 on its own keeps much of what made R410A work well while dropping the component with the higher global warming potential.
Why R32 replaced R410A
| R32 | R410A | |
|---|---|---|
| Type | Single substance | Blend of R32 and R125 |
| Global warming potential | 675 | 2,088 |
| Safety class | A2L, mildly flammable | A1, no flame spread |
| Ozone depletion | None | None |
The main reason for the change is global warming potential. Kilogram for kilogram, R32 has roughly a third of the warming effect of R410A if it escapes. It also carries heat well, so a system usually needs less refrigerant than an equivalent R410A system, which reduces the effect of any leak further.
Rules on high-GWP refrigerants are tightening, and the industry is moving to lower-GWP options. R32 is one step on that path; natural refrigerants such as R290 are another.
Mildly flammable: what that means
R32 is classed A2L: lower toxicity and mildly flammable. It is hard to ignite, burns slowly if it does, and a home split system holds only a small amount, typically around 0.5 to 1.5 kg.
In practice:
- installation instructions set out where units can go and, for larger charges, the minimum size of the room;
- engineers use tools and procedures suited to flammable refrigerants, and keep sources of ignition away while they work;
- the equipment itself is designed and tested for it.
Day to day, living with an R32 system is no different. If you ever suspect a leak, switch the system off, keep naked flames away, open a window and call an engineer.
Pressures and pipework
R32 works at pressures similar to R410A's, a little higher. Systems, pipework and tools have to be rated for it, and a system built for one refrigerant can't simply be refilled with another. When an old system is replaced, whether its pipework can be reused depends on its condition and size, and on the new unit's installation instructions.
The copper pipes, joints and testing that go into an installation are covered in refrigerant pipework explained.
What to check
The rating plate on the outdoor unit, and the specification sheet, show which refrigerant a system uses and how much it holds. For a home R32 system, that amount is far below the level where mandatory leak checks apply. Those start at 5 tonnes CO2-equivalent, which for R32 means roughly 7.4 kg of refrigerant.
If you're comparing systems, the refrigerant is worth a glance, but it's rarely the deciding factor. Correct sizing, efficiency and a careful installation matter more to how the system performs and whether it ever leaks.
Related guides
- Refrigerants explainedA refrigerant is the fluid that carries heat around an air conditioner, boiling to absorb it and condensing to release it. Refrigerants differ in their pressures, efficiency, flammability and effect on the climate, which is why the choice matters.
- Global warming potential explainedGlobal warming potential (GWP) compares how much a gas warms the climate with the same mass of carbon dioxide, usually over 100 years. A refrigerant's GWP shows how much harm a leak would do, and it underpins the rules on refrigerants.
- Older refrigerants: R22 and R410AR22 damages the ozone layer and can no longer be used to service equipment, so a leaking R22 system usually means replacement. R410A is still widely used and can be serviced, but its high global warming potential means most new systems use R32.
- Refrigerant pipework explainedTwo insulated copper pipes carry refrigerant between the indoor and outdoor units. They are joined at each unit, tested for leaks and cleared of air before use, and their length and route affect how the job looks and whether extra refrigerant is needed.