The short answer
Refrigerant is the fluid that carries heat around an air conditioner’s sealed loop, boiling and condensing as it absorbs and releases heat. Modern systems commonly use R32, which has a lower global-warming potential than the older R410A. Refrigerants are fluorinated gases, so under GB F-gas law only an F-Gas-certified engineer may install, charge, service or remove them. DIY refrigerant work is illegal, and venting it to the air is an offence.
Refrigerant is the unsung hero of air conditioning: without it there is no heat to move and no cooling. But it is also why the whole sector is legally regulated. Because these fluorinated gases are potent greenhouse gases if released, GB F-gas law tightly controls who may handle them and how. This guide explains what refrigerant is, the common types, and the rules that protect both the climate and you.
Refrigerant at a glance
- What it is A heat-carrying fluid in a sealed loop
- Common type R32 (lower GWP than R410A)
- Older type R410A (being phased down)
- Legal status Fluorinated greenhouse gas (F-gas)
- Who may handle F-Gas-certified engineers only
- Venting it An offence under GB F-gas law
What refrigerant does
Refrigerant is a fluid specially chosen to boil and condense at convenient temperatures for the job. As it boils at the indoor coil it absorbs a large amount of heat from the room air; as it condenses at the outdoor coil it releases that same heat to the outside. This change of state — liquid to gas and back — is the trick that lets an air conditioner move so much heat for so little electricity, the mechanism set out in how air conditioning works. The fluid lives permanently in a sealed loop and, in normal operation, should never need “topping up”. That point is widely misunderstood: unlike fuel or oil, refrigerant is not consumed. If a system is low on refrigerant, it has a leak that needs finding and fixing, not simply refilling.
Common refrigerant types
The refrigerants used have changed over the years as the law has driven the industry toward gases that do less damage if they escape. The key measure is global-warming potential (GWP) — how strong a greenhouse gas the refrigerant is compared with carbon dioxide.
- R32: the current mainstream choice for new domestic splits. It has a markedly lower GWP than R410A and is more efficient, so a system needs less of it to do the same job.
- R410A: widely used in older systems but being phased down under F-gas rules because of its higher GWP. Systems using it remain legal to run and service, but supplies of the gas tighten over time.
- Newer low-GWP options: manufacturers are moving toward refrigerants with ever-lower GWP as the phase-down continues, which is one reason to favour a current model.
| Refrigerant | Typical use | GWP position |
|---|---|---|
| R32 | Most new domestic splits | Lower — favoured now |
| R410A | Older systems | Higher — being phased down |
| Low-GWP next-gen | Emerging | Lowest — future direction |
The law: who may handle it
Refrigerants are fluorinated greenhouse gases, regulated under the Fluorinated Greenhouse Gases Regulations 2015 (GB F-gas). Under this law, only an F-Gas-certified engineer working for an F-Gas-registered company may install, commission, service, repair or decommission equipment containing these gases. DIY refrigerant work is illegal, and deliberately venting refrigerant to the atmosphere is a specific offence. The rules also require that refrigerant is recovered for reuse or proper disposal at the end of a system’s life rather than released, and that systems above certain charge sizes are leak-checked at set intervals with records kept. The F-Gas Register, and bodies such as REFCOM, record the certified businesses and engineers permitted to do this work, so you can verify an installer. Note that Northern Ireland may differ from Great Britain on some F-gas details, so check the position for your location.
Leaks, safety and re-gassing
Because a correctly installed system loses no refrigerant, a unit that genuinely needs a re-gas almost always has a leak that must be located and repaired first. Simply refilling a leaking system is poor practice: it wastes gas, releases a potent greenhouse gas, and the unit will soon be low again. A re-gas typically costs £100–£300 when genuinely required, but the leak detection and repair is the real job and the real cost. On safety, some modern refrigerants such as R32 are classed as mildly flammable, which is a further reason handling is restricted to trained engineers using the correct tools, leak detectors and ventilation. A reputable engineer will always investigate why a charge is low rather than just topping it up.
In short, refrigerant is the heat-carrying heart of your system and the very reason air conditioning is legally regulated. Choose a system using a modern low-GWP refrigerant such as R32, keep it leak-free with regular servicing, and leave every part of the refrigerant work to certified engineers.
Concerned about refrigerant or a leak?
Never touch the refrigerant yourself — book an F-Gas-certified engineer to find and fix any leak and recharge the system legally.
Frequently asked questions
What refrigerant do modern air conditioners use?
Most new domestic splits use R32, which has a lower global-warming potential than the older R410A and is more efficient, so less is needed.
Can I top up the refrigerant myself?
No. It is illegal under GB F-gas law to handle refrigerant without certification, and venting it is an offence. Only an F-Gas-certified engineer may recharge a system.
Why does my air con need re-gassing?
A sealed system shouldn’t lose refrigerant, so low gas means a leak. The leak must be found and repaired, not just refilled.
Is air conditioning refrigerant dangerous?
Handled by a certified engineer it is safe. Some types like R32 are mildly flammable and all are regulated greenhouse gases, which is why DIY work is banned.
Sources & further reading
- gov.uk — The Fluorinated Greenhouse Gases Regulations 2015 (GB F-gas)
- gov.uk — DEFRA F-gas guidance and the phase-down of high-GWP refrigerants
- HSE — safe handling of refrigerants and flammable gases
- REFCOM / F-Gas Register — certified F-gas businesses and engineers
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.