Short answer: In Great Britain, only F-gas certified engineers may install, service or repair the refrigerant circuit of an air conditioner. Since 1 January 2025, new single-split systems holding under 3 kg of refrigerant with a GWP of 750 or more, such as R410A, can no longer be placed on the GB market. Most single-room home systems are below the legal leak-check threshold, but larger multi-split systems can be above it.
Certified engineers
Refrigerant handling is a regulated activity. The engineer connecting, charging or repairing your system must hold the right F-gas qualification, and the company doing the work needs company certification. Ask to see both before work starts. A plumber or electrician without F-gas certification cannot legally connect a split system.
The 2025 single-split ban
From 1 January 2025, single split air conditioners containing less than 3 kg of fluorinated gas with a global warming potential of 750 or more can no longer be placed on the GB market. That ended new R410A and R407C single splits. Existing systems can still be used, serviced and repaired. GB regulators updated their guidance in August 2026.
Do home systems need leak checks?
Leak checks become a legal requirement when a system holds 5 tonnes CO₂ equivalent or more of HFC refrigerant: roughly 2.4 kg of R410A or 7.4 kg of R32. A typical single-room system holds well under 2 kg, so it is below the threshold. A large multi-split or ducted system can be above it, in which case it needs checking at least every 12 months, with records kept.
Why topping up is not a fix
Air conditioning is a sealed system. If it is low on refrigerant, there is a leak. The leak should be found and repaired, the system pressure tested and then recharged by weight. Topping up without a repair wastes money and releases greenhouse gases.
Northern Ireland
Northern Ireland follows the EU F-gas Regulation (EU) 2024/573 rather than the GB rules. Engineer certification and the leak-check thresholds for HFC systems are similar, but some product rules differ. We confirm what applies to your system.
Related services
Sources
More guides
- How much does air conditioning cost to install in the UK?
- How much does air conditioning cost to run?
- What size air conditioner do I need?
- Fixed split or portable air conditioning?
- Do you need planning permission for air conditioning?
- The £2,500 grant for air-to-air heat pumps explained
- R32, R410A and R22: refrigerants explained
- Is air conditioning the same as a heat pump?
- What happens on air conditioning installation day
- Air conditioning noise and your neighbours
- Looking after your air conditioning: an owner's checklist
- Can you fit air conditioning in a listed building?
- Air conditioning in a flat: leases, freeholders and planning
- Keeping a home cool in a heatwave
- Multi-split or separate single systems?
Reviewed October 2026. Rules and prices change; check the date and ask us if anything is unclear.