R290, R32, R410A: what the gas in your aircon means
Published 24 Jul 2026 · GWP values: IPCC AR4, as used in the GB F-gas regime · gov.uk F-gas guidance · checked 24 Jul 2026
The refrigerant inside the unit decides most of its climate footprint, some of its running cost, and increasingly what your installer is allowed to do with it. The short version for 2026: where you can choose R290 (propane), choose it — it is the greenest gas in domestic kit by a factor of two hundred. For a conventional split system the market still mostly means R32, which is a respectable second. R410A is the legacy gas you should not accept in new equipment.
What does the gas actually change?
Two things. First, leaks. Refrigerants escape — slowly in service, sometimes all at once at end of life — and each gas has a global warming potential (GWP) measured against CO₂. The numbers are not close: R410A scores 2,088, meaning a kilogram leaked does the warming work of two tonnes of CO₂. R32 scores 675. R290 scores about 3.
Second, the rules that follow those numbers. The GB F-gas regime caps how much high-GWP refrigerant can be placed on the market, and the cap tightens over time. That is why R410A is disappearing from new equipment and why servicing an old R410A system gets steadily less pleasant on price. R290 is a hydrocarbon, not an F-gas, so it sits outside the quota system entirely.
GB F-gas Regulation (retained Regulation (EU) 517/2014) · HFC phase-down quotas · checked 24 Jul 2026
Which gas should a new install use in 2026?
Start from the green end. R290 first, wherever the format allows it. For a monobloc or a portable, R290 is increasingly standard and there is no reason to accept anything else: GWP about 3, outside the F-gas quota system entirely, and — a useful side effect for flats — no F-gas-certified engineer is legally required to install it, though the engineer still needs competence with flammable refrigerants. The same goes for many air-to-water heat pumps, where R290 has become the quality marker. The trade’s own training literature makes the environmental case for hydrocarbons plainly.
Kelly, Refrigeration, Air Conditioning and Heat Pump Technology Manual · Business Edge · reference for the hydrocarbon case
For a wall-split system, the honest position: R290’s flammability class keeps it out of most split indoor units for now, so the practical answer today is R32 — and it should arrive as standard without you asking. It has been the mainstream choice for new UK splits for several years: better efficiency than R410A, a third of the GWP, and a single-compound gas that is far easier to recover and recycle than the R410A blend. Propane splits are beginning to appear from European makers; if an installer offers one with the safety case properly done, it is the greener machine. If a 2026 quote specifies R410A, ask why. There will not be a good answer.
Is R32 dangerous?
It is classed A2L: mildly flammable, hard to ignite, and the reason charge sizes and siting rules exist for indoor units. Handled by a certified installer following the manufacturer’s limits, it is an unremarkable risk — millions of UK homes already have it. R290 burns more readily (class A3), which is why you find it in small-charge sealed monoblocs and outdoor units rather than pumped around your living room wall.
What about the system you already own?
Keep running it. An existing R410A system is legal and serviceable; nothing requires replacement. The economics just lean one way from here: quota pressure makes R410A top-ups dearer each year, and when the compressor eventually dies, the replacement will be R32 or R290 and cheaper to live with. If you are choosing between repairing a tired R410A unit and replacing it, the gas is now a real line in that sum.
One planning footnote: the gas has no bearing on permitted development. The route cares whether the unit heats as well as cools, its size, and the noise calculation — not what is in the pipes. The law, with citations.