Air conditioning regas

What a regas really is

“Regas” is the everyday word for putting refrigerant back into an air conditioning system. It sounds like routine maintenance, like topping up oil in a car, but it isn’t. An air conditioning system is a sealed circuit. The refrigerant isn’t used up as it runs. It goes round and round, absorbing heat indoors and giving it up outdoors, for the life of the system.

So if a system is short of refrigerant, it has leaked out. The leak might be at a flare joint, a valve, a brazed joint or in a coil, and it might be tiny. Adding refrigerant without finding the leak means paying for gas that will escape again, sometimes within weeks, while the system runs short and works harder than it should. A proper regas is a leak repair followed by a recharge.

Signs a system may be short of refrigerant

• Cooling or heating that has faded gradually over weeks or months, even with clean filters.
• Ice or frost on the indoor coil, or on the pipework near the indoor or outdoor unit.
• The system running for long periods without reaching the set temperature.
• A hissing or bubbling sound near the pipe connections.
• Oily marks on joints or valves, which can show where refrigerant oil has escaped with the gas.
• A low-pressure or similar error code, depending on the brand.

Some of these signs have other causes too, such as a blocked filter, a failing fan or a faulty sensor. That is why we measure first rather than assume. Our article on ice on an air conditioning unit covers the other common causes.

The rules on refrigerant

Air conditioning refrigerants such as R32 and R410A are fluorinated gases. Companies that work on equipment containing them must be certified by an approved body, and the engineers need their own qualifications (GOV.UK: company certification; engineer qualifications). AirCon Doctor is an F-Gas certified company.

Responsibility for stopping leaks is shared between the people who use the equipment and the technicians who look after it. GOV.UK’s leak checking guidance says that if you find a leak, you must repair it as soon as possible and repeat the test within a month to check the repair worked (GOV.UK: checking F-gas equipment for leaks). Larger systems also need periodic leak checks, set by the amount of refrigerant measured in tonnes of CO2 equivalent. This is general information, not legal advice.

How we regas a system

1. We check the system running and measure its pressures and temperatures to confirm it is short of refrigerant rather than suffering from another fault.
2. We search for the leak with electronic detection and other leak-finding methods, checking joints, valves and coils.
3. The leak is repaired. Where a part such as a coil or valve has failed, we tell you before replacing it.
4. Any refrigerant left in the circuit is recovered where the repair needs it, then the circuit is pressure tested to prove the repair holds.
5. The system is evacuated with a vacuum pump to remove air and moisture.
6. It is recharged by weight to the charge on the manufacturer’s nameplate, then run and checked in cooling and heating.
7. The work and the refrigerant added or recovered are recorded, and the repair is rechecked as the guidance requires.

R32, R410A and older systems

Most new split systems use R32, which has a global warming potential of 675. Many systems from the last two decades use R410A, with a global warming potential of 2,088. Both figures come from the annex to Regulation 517/2014. Repairs and recharges on existing R410A systems remain legal, but the GB phase-down of HFC supply is tightening, so R410A is getting scarcer and dearer to buy. For an older R410A system that leaks repeatedly, replacement can work out better value than another repair.

Systems running on R22 are a different case. R22 is an ozone-depleting HCFC and its use for servicing ended years ago, so an R22 system can’t simply be topped up. Our guide to R410A and R22 systems explains the choices. GOV.UK sets out the bans on F gas in new equipment.

Why DIY gas kits are a bad idea

Refrigerant top-up cans and kits are sold online, but working on the refrigerant circuit of an air conditioning system is a job for a certified company with qualified engineers. Without the right gauges, scales and vacuum pump, it is impossible to know how much refrigerant is in the system, and the leak stays where it was. Adding the wrong refrigerant or letting air and moisture in can damage the compressor. If you have a pre-charged DIY system that is now short of gas, our article on pre-charged kits explains what to do next.

What it costs

The cost depends on where the leak is, how easy it is to reach, the refrigerant type and how much is needed. Because of that, we don’t publish a set regas price. A diagnosis visit starts from £75 + VAT, and once the engineer has found the leak you get a fixed price for the repair and recharge before any work goes ahead. On a well-maintained system, an annual service is often where a slow leak is first spotted, while it is still small.