F-Gas certification decides who may open a refrigerant circuit. Category 1 covers every activity; the other categories are limited by charge size or by the task.
Anyone who installs, services, leak-checks, recovers from or decommissions stationary refrigeration, air-conditioning or heat-pump equipment containing fluorinated gases in Great Britain needs a personal F-gas certificate, and the business needs a company certificate. Category 1 is the full certificate and the one most installers take. This guide explains what the regulation asks of you, how the four personnel categories differ, the leak-check and record duties you inherit on every job, and where the certificate stops and starts for heat-pump work.
What F-gases are and why the certificate exists
Fluorinated greenhouse gases — hydrofluorocarbons such as R-410A, R-32 and R-134a, plus perfluorocarbons and sulphur hexafluoride — are the working fluids in most refrigeration, air-conditioning and heat-pump circuits. They do not damage the ozone layer, but their global warming potential is hundreds or thousands of times that of carbon dioxide, so a leak of a few kilograms has the climate effect of tonnes of CO₂. The rules therefore control who may handle the gas, how equipment is checked for leaks and what happens to refrigerant at the end of its life.
In Great Britain the controls come from the F gas regulation retained in UK law after 2020 (the regime built on EU Regulation 517/2014), administered by the Environment Agency with the devolved regulators. Northern Ireland continues to follow the EU regime, which was replaced in the EU during 2024, so a certificate or a duty that applies in England, Scotland and Wales is not automatically the same in Northern Ireland or in an EU member state. The government guidance also records the HFC phase-down: a 79 % cut in the CO₂-equivalent quantity placed on the market by 2030 against the 2009–2012 baseline, which is why high-GWP refrigerants are being priced and designed out.
Who needs an F-gas certificate
The personal certificate is required for six activities on stationary refrigeration, air-conditioning and heat-pump (RACHP) equipment that contains F-gas: installing new systems, servicing and maintaining them, checking for leaks, recovering gas, decommissioning and disposing of old systems, and working on the refrigeration units of trucks over 3.5 tonnes and trailers. The company that employs you needs its own company certificate to install, service, maintain, repair or decommission that equipment, and refrigerant may only be sold to holders of the relevant certificate.
Personnel qualifications are issued by awarding and certification bodies recognised for the purpose — City & Guilds, the Building Engineering Services Association and LCL Awards are the ones the government guidance names, with CITB no longer issuing new ones. A UK F-gas certificate is not valid for work in the EU, and an installer who moves between the two systems needs the certificate that matches the jurisdiction of the job.
Categories I to IV: what each allows
- Category I: every listed activity on any size of system — installation, maintenance and servicing, leak checking, recovery and decommissioning. This is the certificate a heat-pump or air-conditioning installer who connects refrigerant pipework needs.
- Category II: installation, maintenance, servicing and recovery on systems containing less than 3 kg of F-gas, or less than 6 kg where the system is hermetically sealed and labelled as such.
- Category III: recovery only, from the same small systems — under 3 kg, or under 6 kg hermetically sealed.
- Category IV: leak checking only, and only where the check does not involve breaking into the refrigeration circuit.
- The kilogram limits describe the charge in the system in front of you, not the size of your business. A domestic split air-conditioning unit or a split heat pump can sit either side of the 3 kg line, so most installers take Category I rather than risk being certified for the wrong job.
Leak checks: the thresholds are in tonnes of CO₂ equivalent
The leak-check duty is triggered by the climate effect of the charge, not its mass: refrigerant quantity multiplied by the gas’s global warming potential. Equipment holding F-gas equivalent to 5 tonnes of CO₂ or more must be checked at least every 12 months; 50 tonnes or more, at least every 6 months; 500 tonnes or more, at least every 3 months, and equipment at that size must also have an automatic leak-detection system. Where a detection system is fitted the intervals can double, so a 5-tonne system with detection is checked every 24 months. Hermetically sealed and labelled equipment is exempt below the equivalent of 10 tonnes of CO₂.
Two worked conversions show why the mass alone misleads. R-410A has a GWP of about 2,088, so 5 tonnes of CO₂ equivalent is roughly 2.4 kg of charge — a modest split system is already inside the regime. R-32 has a GWP of about 675, so the same threshold is about 7.4 kg, which is why many domestic R-32 heat pumps fall below the mandatory check. When a leak is found it must be repaired promptly and the repair proved by re-testing within a month.
Records: what is kept, by whom and for how long
- Records are required for equipment containing F-gas equivalent to 5 tonnes of CO₂ or more: the quantity and type of gas installed, any gas added during maintenance or leak repair, the dates and results of every mandatory leak check, and what was done to recover and dispose of gas, with the recycling or reclamation facility’s details where used.
- The operator — the owner or user of the equipment — must keep the records for five years, together with the name, address and certificate number of every company that installed, serviced or decommissioned the equipment.
- The installer’s duty is to supply the entries: what you charged, what you recovered, what the leak check found and your company certificate number. On a service visit, an F-gas log that does not match the plant is a finding in its own right.
Recovery, evacuation and the safety classes
Venting refrigerant is prohibited. Before a circuit is opened for repair, component replacement or decommissioning the charge is recovered into an approved recovery cylinder, and before a system is charged it is evacuated to remove air and moisture. The revision questions on this subject keep returning to the same distinctions: recovered gas destined for reuse against gas destined for destruction, a recovery cylinder against a supply cylinder, and the fill limits that stop a cylinder becoming hydraulically full as it warms.
Refrigerants are also classified for safety: A1 for low toxicity and no flame propagation, A2L for lower flammability (R-32 is the common example), A2 and A3 for flammable gases such as propane, R-290. The class changes the charge limits allowed in an occupied room, the tooling and ventilation you need, and whether a leak check can be done with the equipment running. A question that names the refrigerant is usually asking you to recognise the class before anything else.
F-gas and heat pumps: where the certificate boundary sits
A monobloc air-source heat pump arrives with its refrigerant circuit factory-sealed; the installer connects water, power and controls and never opens the circuit, so installing it is not F-gas work, although the operator’s leak-check and record duties still apply above the thresholds. A split heat pump or a split air-conditioning system is different: connecting and commissioning the refrigerant lines is installation on a live circuit and needs a Category I certificate and a company certificate. That is the boundary the air source heat pump notes describe, and the reason plumbing and heating firms moving into heat pumps often add F-Gas Category 1 to their gas or MCS qualifications rather than replace them.
How the assessment usually runs, and how to revise for it
The common route is City & Guilds 2079-11, the Category I award, which centres normally assess as a knowledge test plus a practical assessment covering leak testing, recovery, evacuation and charging on training rigs; the centre confirms the exact format, duration and any pre-course requirements. Knowledge questions tend to test four things: which category permits which activity, the CO₂-equivalent arithmetic behind leak-check frequency, what a compliant record contains, and safe handling of cylinders and flammable refrigerants.
Revise by keeping quantities and responsibilities separate. Work every threshold question in tonnes of CO₂ equivalent before comparing it with a kilogram figure, name the category before deciding whether an activity is allowed, and decide whether a duty belongs to the operator or the certified person. The F-Gas revision notes and questions on this site are organised around exactly those distinctions.
Quick answers
Do I need an F-gas certificate to install a monobloc heat pump?
Not for the installation itself, because the refrigerant circuit is factory-sealed and you do not break into it. You do need one to install a split system, to recover gas, or to repair anything on the refrigerant side, and the operator’s leak-check and record duties still apply to the equipment once it holds F-gas above the thresholds.
What is the difference between Category 1 and Category 2?
Category I covers every activity on any size of system. Category II covers installation, maintenance, servicing and recovery only on systems holding less than 3 kg of F-gas, or less than 6 kg if the system is hermetically sealed and labelled. Category III is recovery only on those small systems, and Category IV is leak checking that does not open the circuit.
Is a UK F-gas certificate valid in the EU?
No. Government guidance states that a UK F-gas certificate, for a company or an individual, is not valid for work in the EU. Northern Ireland follows the EU regime, so check the position there separately.
How often does a system have to be leak-checked?
Every 12 months from 5 tonnes of CO₂ equivalent, every 6 months from 50 tonnes and every 3 months from 500 tonnes, where an automatic leak-detection system is also required. A fitted detection system doubles each interval. Hermetically sealed and labelled equipment is exempt below the equivalent of 10 tonnes of CO₂. Convert the charge with the refrigerant’s GWP before deciding which band applies.
Does an F-gas certificate expire?
Certificates issued under the current GB regulation carry no expiry date, but the EU introduced renewal under its 2024 rules and the GB regime has been under review, so check the current guidance and your certification body before assuming a certificate from years ago is still all you need. Refresher training is worth doing anyway because refrigerants and safety classes have changed.
Who keeps the F-gas records — the installer or the customer?
The operator of the equipment keeps them, for five years, including the details of every company that worked on it. The certified installer or service company supplies the entries for the work it did: gas installed or added, gas recovered, leak-check dates and results, and its company certificate number.
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