Quick answer
In Great Britain, stationary air conditioning, refrigeration and heat pump systems containing F gas equivalent to 5 tonnes of CO2 or more must be leak checked at least every 12 months, rising to every 6 months from 50 tonnes. Automatic leak detection doubles the interval and is mandatory from 500 tonnes. Operators must keep records for 5 years.
Why F-gas rules matter to building operators
Most commercial air conditioning, VRF systems, chillers and heat pumps use hydrofluorocarbon (HFC) refrigerants. These are fluorinated greenhouse gases (F gases) with a global warming effect hundreds or thousands of times greater than carbon dioxide.
In Great Britain, the F-gas rules make the user or operator of the equipment responsible for having it leak checked, while the service technicians who install and maintain it share responsibility for preventing leaks. Not having the right leak checks in place, or not fixing leaks, can lead to a civil penalty from the Environment Agency.
This guide summarises the GOV.UK guidance for stationary air conditioning, refrigeration and heat pump systems in Great Britain. Northern Ireland follows the EU F-gas rules.
Step 1: work out the CO2 equivalent
Leak check frequency depends on the tonnes of CO2 equivalent (tCO2e) in each system, not the kilograms of refrigerant:
tCO2e = refrigerant charge (kg) × GWP ÷ 1,000
The charge is on the unit’s data plate or in the installation records. For VRF and split systems, it includes any additional refrigerant added on site for long pipe runs, which should be recorded on a label at the outdoor unit.
Approximate charge at which common refrigerants reach each threshold:
| Refrigerant | GWP | 5 tCO2e | 50 tCO2e | 500 tCO2e |
|---|---|---|---|---|
| R410A | 2,088 | 2.4 kg | 24 kg | 239 kg |
| R407C | 1,774 | 2.8 kg | 28 kg | 282 kg |
| R134a | 1,430 | 3.5 kg | 35 kg | 350 kg |
| R32 | 675 | 7.4 kg | 74 kg | 741 kg |
| R404A | 3,922 | 1.3 kg | 13 kg | 127 kg |
R410A, R407C, R134a and R404A figures are from the GOV.UK leak check guidance. The R32 figures are calculated from its GWP.
Step 2: set the leak check frequency
| CO2 equivalent in the system | Minimum leak check frequency | With automatic leak detection |
|---|---|---|
| Less than 5 tonnes | No mandatory interval | n/a |
| 5 to less than 50 tonnes | Every 12 months | Every 24 months |
| 50 to less than 500 tonnes | Every 6 months | Every 12 months |
| 500 tonnes or more | Automatic leak detection is mandatory | Every 6 months |
Two further points:
- Hermetically sealed systems have no maximum interval unless they contain 10 tonnes CO2 equivalent or more.
- Where an automatic leak detection system is fitted, it must alert you or your service company to a leak and must itself be checked every year.
Large VRF systems serving whole floors often hold enough R410A to fall into the 6-monthly band. Check each system rather than assuming.
Step 3: repair leaks properly
If a leak is found, the rules require it to be repaired as soon as possible and the system re-checked within one month to confirm the repair worked. Signs of a leak between checks include gradual loss of cooling, ice on pipework, oil staining at joints and frequent low-pressure alarms. See why commercial HVAC stops cooling.
Recharging a system without finding and fixing the leak is not a repair.
Step 4: keep the records
For each system holding 5 tCO2e or more, the operator must keep records for five years covering:
- the quantity and type of refrigerant in the system when installed
- refrigerant added during maintenance or repairs
- the dates and results of all mandatory leak checks
- refrigerant recovered and how it was disposed of, including the waste carrier
- if recycled or reclaimed gas was used, the quantity and the facility’s details
- the name, address and certificate number of every company that installs, services or decommissions the equipment
The Environment Agency can ask to see these records. A single F-gas log per system, kept with your planned maintenance records, is the simplest way to stay organised.
Step 5: check who is doing the work
- Companies that install, repair, maintain or decommission stationary air conditioning, refrigeration or heat pumps for other businesses must hold F-gas company certification from an approved body: REFCOM, F-Gas Register (Quidos) or Bureau Veritas. Certification is renewed every three years.
- Individuals who handle F gas must hold the relevant personal qualification.
Ask for the company certificate number and the engineers’ qualifications before work starts, and record them in your F-gas log. Our guide to choosing an HVAC contractor lists other questions worth asking.
Older refrigerants and future planning
- Virgin refrigerant with a GWP above 2,500, such as R404A, cannot be used to refill systems holding 40 tCO2e or more. Reclaimed or recycled gas can be used until 2030.
- From 2025, new single split air conditioning systems holding less than 3 kg of refrigerant cannot use F gases with a GWP of 750 or more. This affects new equipment, not the continued use of existing systems.
If your systems use older refrigerants, factor this into replacement planning. See commercial HVAC replacement factors and HVAC installation.
Building leak checks into maintenance
The simplest way to stay compliant is to include statutory leak checks in a planned maintenance contract, scheduled from an asset register that records each system’s refrigerant type, charge and tCO2e. Talk to us about commercial HVAC maintenance or call 020 7998 9005.
Frequently asked questions
Who is responsible for F-gas leak checks?
The operator of the equipment, usually the business that has control over how it runs, is responsible for making sure leak checks happen. If equipment is rented, responsibility depends on the rental agreement. The checks themselves must be done by qualified technicians from a certified company.
How do I calculate tonnes of CO2 equivalent?
Multiply the refrigerant charge in kilograms by the refrigerant's global warming potential (GWP), then divide by 1,000. For example, 10 kg of R410A (GWP 2,088) is about 20.9 tonnes CO2 equivalent.
Can a leaking system just be topped up?
No. If a leak is found it must be repaired as soon as possible, and the system must be checked again within one month to confirm the repair worked. Recharging without finding the leak wastes refrigerant and does not meet the rules.
Do small split systems need leak checks?
It depends on the charge and refrigerant. A system holding less than 5 tonnes CO2 equivalent has no mandatory leak check interval. Hermetically sealed systems below 10 tonnes are also exempt. Many single splits fall below these thresholds, but larger VRF systems usually do not.
What qualifications should the engineer have?
Individuals handling F gas need personal F-gas qualifications. A company servicing other people's air conditioning must hold company certification from an approved body such as REFCOM, F-Gas Register (Quidos) or Bureau Veritas. Ask to see both.
UK guidance and references
Primary and industry sources relevant to this subject. Always check the current edition and how it applies to your building.
This guide is general information for commercial building operators. It does not replace an assessment of your building by a competent engineer. If there is an immediate risk to people, contact the emergency services first.