The short answer
A re-gas means recharging the refrigerant in an air-con system — but it should only follow a leak repair. A sealed circuit does not consume refrigerant, so a low charge means a leak; topping up without fixing it just vents greenhouse gas and wastes money. A re-gas typically costs £100–£300 and must be done by an F-Gas-certified engineer — DIY refrigerant work is illegal under GB F-gas law.
“It just needs a re-gas” is one of the most misunderstood phrases in air conditioning. Refrigerant is not a consumable like fuel; a system that has lost charge has a leak. This guide explains what re-gassing involves, why the leak must be found and fixed first, what it costs, and why the whole process is tightly regulated and reserved for certified engineers.
Re-gas at a glance
- Typical cost £100–£300
- Low charge means A leak, not normal loss
- Right order Find leak → repair → recharge
- Who may do it F-Gas-certified engineers only
- DIY Illegal under GB F-gas law
- Sign of low charge Weak cooling, icing
What a re-gas actually is
Re-gassing means recovering the existing refrigerant and recharging the system to the manufacturer’s specified weight. Refrigerant is the working fluid that carries heat out of your room — see refrigerant explained. The crucial point most people miss is that an air-con circuit is sealed: in normal operation it does not use up refrigerant the way an engine uses fuel. So if a system is low on charge, it is not because the gas has been “used” — it is because it has leaked out. A re-gas is therefore not routine maintenance; it is a repair, and it should always come after the leak has been found and fixed.
Why topping up alone is the wrong fix
Simply adding refrigerant to a leaking system is poor practice for three reasons.
- It doesn’t last — the gas leaks out again, so you pay repeatedly for the same problem.
- It vents greenhouse gas — refrigerants are potent greenhouse gases, and deliberately running a known leak is environmentally and legally unacceptable.
- It hides damage — running low on charge strains the compressor and can ice the coil, causing further faults.
A competent engineer follows the correct sequence: leak-test the system, repair the leak, evacuate the circuit, then recharge to the precise specified weight. That is why a proper job costs more than a quick “splash and dash” — and why the cheap version is a false economy.
| Step | What happens | Why |
|---|---|---|
| Leak test | Find where refrigerant escapes | No point recharging a leak |
| Repair | Fix the joint, coil or component | Stops recurrence |
| Evacuate | Remove air and moisture | Protects the system |
| Recharge | Add the exact specified weight | Restores full cooling |
The law: re-gassing is restricted
Under the GB F-gas regime, refrigerant is a controlled fluorinated greenhouse gas. Only an F-Gas-certified engineer, working for an F-Gas-registered company, may recover, handle or charge refrigerant. DIY re-gassing is illegal — the cans of refrigerant sometimes sold online are not a lawful route for a fixed system, and using them risks injury, damage and prosecution. Larger systems also carry a legal duty to be leak-checked at set intervals, and any recovered refrigerant must be handled and recorded properly rather than vented to the atmosphere.
This regulation exists for good reasons beyond bureaucracy. Refrigerants are potent greenhouse gases, so deliberately running or topping up a leaking system has a real environmental cost; the law is designed to minimise leakage and ensure gas is recovered rather than released. It also protects people: refrigerant under pressure can cause cold burns and, in an enclosed space, displace oxygen, so handling it safely needs training and the right equipment. Re-gassing is therefore not a job you can or should do yourself — it is skilled, regulated work for a certified professional, and that is reflected in both the price and the paperwork you should receive.
Cost and when you need one
A re-gas typically costs £100–£300, depending on the refrigerant type and amount and the extent of any leak repair. Tell-tale signs that a system is low on charge include weak cooling, the unit running constantly without reaching temperature, and ice forming on the coil or pipes — see air con not cooling. If you notice these, switch the system to an annual service footing and have a certified engineer investigate rather than just topping up — see servicing explained. This page is general guidance; only a certified engineer who has tested your system can confirm whether it needs a leak repair and re-gas.
Air-con low on gas or icing up?
Get matched with an F-Gas-certified engineer to leak-test, repair and recharge your system properly — not just top it up. A quote costs nothing.
Frequently asked questions
How much does an air-con re-gas cost?
Typically £100–£300, depending on the refrigerant type and quantity and any leak repair needed. A proper job includes finding and fixing the leak first.
Does air-con lose refrigerant naturally?
No. A sealed circuit does not consume refrigerant. If the charge is low, there is a leak that must be found and repaired before recharging.
Can I re-gas my air-con myself?
No. Handling refrigerant is legally restricted to F-Gas-certified engineers. DIY re-gassing is illegal, dangerous and vents greenhouse gas.
How do I know if my air-con needs a re-gas?
Signs include weak cooling, the unit running constantly, and ice on the coil or pipes. These suggest a leak — have a certified engineer test it rather than just topping up.
Sources & further reading
- GOV.UK — F-gas: guidance for users, producers and traders
- The Fluorinated Greenhouse Gases Regulations 2015 (GB F-gas)
- REFCOM / F-Gas Register — certified engineer requirements
- Manufacturer technical data (Daikin, Mitsubishi Electric) — refrigerant charge
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.