F-Gas leak-check intervals explained (UK): how often must your air conditioning be checked?
F-Gas · 18 June 2026 · 6 min read
Most air conditioning and refrigeration systems in the UK contain fluorinated greenhouse gases (F-gases) such as R-410A, R-32 or R-134a. If you operate equipment that contains them, you have legal duties under the GB F-Gas Regulation — the retained version of EU Regulation 517/2014. The duty that catches people out most often is the leak check: how frequently you must have the system inspected for leaks, and by whom.
The interval isn't fixed per system type. It's driven by how much warming potential the refrigerant charge represents — its CO₂ equivalent.
How the interval is calculated
Every refrigerant has a Global Warming Potential (GWP) — a multiplier relative to carbon dioxide. The CO₂ equivalent of a system is simply its charge multiplied by that GWP:
CO₂e (tonnes) = refrigerant charge (kg) × GWP ÷ 1000
So the same 10 kg of refrigerant can put you in completely different leak-check bands depending on which gas it is. A few common GWPs:
| Refrigerant | GWP |
|---|---|
| R-32 | 675 |
| R-407C | 1,774 |
| R-410A | 2,088 |
| R-134a | 1,430 |
| R-404A | 3,922 |
| R-454B | 466 |
The leak-check intervals
Once you know the CO₂e, the minimum leak-check frequency follows directly. Where a fixed automatic leak-detection system is installed, the interval is doubled:
| System charge (CO₂e) | Minimum check | With leak detection |
|---|---|---|
| Below 5 tonnes | No statutory interval* | — |
| 5 to 50 tonnes | Every 12 months | Every 24 months |
| 50 to 500 tonnes | Every 6 months | Every 12 months |
| 500 tonnes or more | Every 3 months | Every 6 months |
*Below 5 tonnes CO₂e there's no statutory leak-check interval, but an annual check remains good practice and is often needed to evidence PPM compliance.
When a leak-detection system is mandatory
For any system at 500 tonnes CO₂e or more, a fixed automatic leak-detection system is not optional — it's a legal requirement, and it must itself be checked at least once every 12 months to confirm it's working.
If a leak is found
A detected leak must be repaired without undue delay. Crucially, a follow-up leak check is required within one month of the repair to confirm it was effective. A passed annual check doesn't close the loop on its own once a leak has been found.
Records you must keep
If your system holds 5 tonnes CO₂e or more, you (the operator) must keep records covering the quantity and type of refrigerant, any amounts added or recovered, the dates and results of leak checks, and the certified company or technician who carried out the work. These records should be kept for at least five years.
A worked example
Take a VRF system charged with 12 kg of R-410A:
12 × 2,088 ÷ 1,000 = 25.1 tonnes CO₂e
That falls in the 5–50 tonne band, so it needs a leak check at least every 12 months — or every 24 months if it has a fixed leak-detection system fitted.
Now the same physical charge as R-32 (12 kg):
12 × 675 ÷ 1,000 = 8.1 tonnes CO₂e
Still in the 5–50 band and 12-monthly — but much closer to the 5-tonne threshold, which is exactly why recording the gas type and charge accurately matters.
Don't confuse this with a TM44 inspection
The F-Gas leak check is about refrigerant containment. It is not the same as the CIBSE TM44 / EPBD air conditioning inspection, which is a separate statutory energy-efficiency assessment required for AC systems over 12 kW of effective rated output, every five years, by an accredited assessor. A maintenance visit and an F-Gas check do not satisfy a TM44, and vice versa.
Getting the interval right, automatically
The arithmetic is simple, but doing it by hand on every visit — and keeping five years of defensible records — is where compliance slips. In ServMeister, the engineer just records the refrigerant and charge; the platform calculates the CO₂e, sets the correct statutory interval, flags when fixed leak detection becomes mandatory, and logs the check against the asset. The F-Gas page becomes part of the same signed report as the rest of the service.
This article is general guidance, not legal advice. Always check the current requirements on gov.uk and confirm your obligations with a certified F-Gas contractor.