Glossary · Air conditioning
What is refrigerant?
Refrigerant is the fluid sealed inside an air conditioner that carries heat from one place to another. It evaporates indoors, absorbing heat from the room air, then is compressed and releases that heat outdoors. In the UK most home units use an HFC gas, and only certified people may handle it.
Key points
- Refrigerant moves heat around a sealed circuit. It is not used up, so a healthy system never needs topping up.
- Common HFC gases have very different warming effects: R32 has a global warming potential of 675 and R410A has 2088.
- In Great Britain, movable air conditioners can no longer be sold with a refrigerant above a global warming potential of 150.
- Working on refrigerant needs a personal F gas qualification, and a company servicing other people's units needs company certification.
How refrigerant works
An air conditioner does not make cold. It moves heat. The refrigerant is the fluid that carries it. In a split system the refrigerant evaporates in the indoor unit and absorbs heat from the room air. The compressor in the outdoor unit then pressurises it and releases that heat outside.[5]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts The room is cooled and dried at the same time.
The circuit is sealed. The refrigerant goes round and round and is not used up. That is why a healthy system never needs a top-up, and why a unit that has lost cooling power usually has a leak somewhere.
Many units can also run the cycle in reverse. In heating mode the system draws heat from the outside air and releases it into the room, which is how an air source heat pump works.[5]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts You can read how this differs from a dedicated heating product in air conditioning vs heat pump.
Types of refrigerant and the rules around them
Most home air conditioners in Great Britain use hydrofluorocarbons, known as HFCs. GOV.UK lists each one with a global warming potential (GWP). This number shows how much a gas warms the climate compared with carbon dioxide if it escapes.[1]Environment Agency and Defra (GOV.UK), Fluorinated gases (F gases)
| Refrigerant | What it is | Global warming potential |
|---|---|---|
| R32 | HFC-32 on its own | 675 |
| R410A | A mixture of HFC-32 and HFC-125 | 2088 |
| R407C | A mixture of HFC-32, HFC-125 and HFC-134a | 1774 |
GOV.UK says the UK is phasing HFCs down by 79% by 2030, measured against average use between 2009 and 2012.[1]Environment Agency and Defra (GOV.UK), Fluorinated gases (F gases) That is why the rules on new equipment are tightening.
Two bans matter to a homeowner. Movable air conditioning equipment, where you can carry the unit between rooms, may not be placed on the market with an HFC above a GWP of 150.[2]Environment Agency and Defra (GOV.UK), Bans on F gas in new products and equipment: current and future New single split systems with less than 3kg of refrigerant face a limit of 750 from 2025.[2]Environment Agency and Defra (GOV.UK), Bans on F gas in new products and equipment: current and future The ban applies to placing new equipment on the market, and GOV.UK describes it in those terms.[2]Environment Agency and Defra (GOV.UK), Bans on F gas in new products and equipment: current and future
Who may handle refrigerant
Handling refrigerant is regulated. GOV.UK says it is against the law to work with F gas without the correct qualifications, and you could receive a civil penalty.[3]Environment Agency and Defra (GOV.UK), Qualifications to work with F gas Each engineer needs a personal certificate. A category 2 certificate covers installing, maintaining and servicing systems with less than 3kg of F gas.[3]Environment Agency and Defra (GOV.UK), Qualifications to work with F gas
The company matters too. A business that services air conditioning owned by other people must be certified by an approved body, and that certification is renewed every 3 years.[4]Environment Agency and Defra (GOV.UK), Company certification to work with F gas Refcom Certification is one of the bodies GOV.UK names.[4]Environment Agency and Defra (GOV.UK), Company certification to work with F gas Bosch adds that refrigerant work, including first filling and refilling, is carried out by qualified personnel, and that new systems are generally pre-charged at the factory in the outdoor unit.[5]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts
Example
Hannah in Shipley has an older split system that runs on R410A. A new single split unit would run on R32. By the GOV.UK figures the R32 number of 675 is under a third of the R410A figure of 2088. The ban in the GOV.UK table is on placing new equipment on the market. If her old system needs work, she should ask the company to show its F gas certification and the engineer’s personal qualification before anyone opens the circuit.
What people get wrong
Many people think a unit that blows warm air just needs “regassing”. The refrigerant is sealed in a closed circuit and is not consumed, so low gas means a leak. Topping up without finding the leak only delays the problem, and legally it is work for a certified engineer.
The second mistake is to treat all refrigerants as the same. They are not. The global warming potential varies widely, and that is why the rules differ between types of unit.
The bottom line
Refrigerant is the working fluid of an air conditioner. It carries heat out of your room in a sealed circuit and is never used up in normal running. R32 has a much lower warming effect than R410A, and the rules on new equipment are moving towards lower figures. Leave all handling to an engineer with a personal F gas qualification working for a certified company.
Common questions
Does an air conditioner need its refrigerant topping up?
Not in normal use. The refrigerant runs in a sealed circuit and is not consumed. If a unit loses cooling because the gas level is low, there is a leak that a certified engineer must find and repair.
Can I top up or change the refrigerant myself?
No. GOV.UK says you must have your own F gas qualification to work on equipment containing F gas, and breaking that rule can bring a civil penalty. Bosch says refilling is done by qualified personnel.
What is the difference between R32 and R410A?
Both are HFC gases. GOV.UK lists R32 with a global warming potential of 675 and R410A with 2088, so R32 has a much smaller warming effect if it leaks.
Why are refrigerants being phased out?
HFCs warm the climate if they escape. GOV.UK says the UK is phasing down HFCs by 79% by 2030 compared with average use between 2009 and 2012.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Environment Agency and Defra (GOV.UK). Fluorinated gases (F gases). Checked 11 November 2026. ↩
- Environment Agency and Defra (GOV.UK). Bans on F gas in new products and equipment: current and future. Checked 11 November 2026. ↩
- Environment Agency and Defra (GOV.UK). Qualifications to work with F gas. Checked 11 November 2026. ↩
- Environment Agency and Defra (GOV.UK). Company certification to work with F gas. Checked 11 November 2026. ↩
- Bosch Home Comfort. Bosch air conditioners and climate control units: key facts. Checked 11 November 2026. ↩