System Keeps Needing Regassing

What's happening?

An air conditioning circuit is sealed. It does not consume refrigerant and it does not need periodic topping up — a system that needs gas has lost gas, and the loss has a location. Repeat top-ups without a repair are a business model rather than a service: the refrigerant goes back into the atmosphere, the underlying fault gets worse, and each recharge leaves the system running on an inaccurate charge. UK law backs this up. Working with F gas without the right individual qualification is an offence, companies servicing other people's equipment must hold their own certification, and where equipment falls within the leak-checking rules a leak must be repaired as soon as possible and re-tested within a month. Deliberately venting refrigerant is not allowed.

What usually causes it?

• Flare joints at the indoor or outdoor unit not made or torqued correctly at installation
• Vibration fatigue cracking a braze or a pipe near the compressor or a bend
• Corrosion of the outdoor coil, common on coastal properties and near road salt
• Physical damage to the pipe run — a nail, a strimmer, a ladder foot, a bracket bolted through insulation
• Schrader valve cores weeping at the service ports
• Poorly supported pipework rubbing through its insulation where it passes through a wall
• Coil failure from formicary corrosion in the indoor head, which shows as very slow loss over years

When should you call an air conditioning engineer?

Call an F gas certified air conditioning engineer as soon as cooling starts fading again. Ask two questions when you book: whether the engineer holds an F gas qualification, and whether the company holds F gas company certification. Both are legal requirements for this work. Ask for a leak test and a repair quote, not a top-up.

What will the air conditioning engineer actually do?

• Confirm the charge is low by pressure and superheat readings rather than assuming
• Leak-test with an electronic detector, and add trace dye or use nitrogen pressure testing on slow leaks
• Repair the leak — remake the flare, replace the valve core, braze or replace the damaged section
• Recover the remaining refrigerant properly instead of venting it
• Evacuate the circuit to remove moisture and air, then weigh in the exact charge the manufacturer specifies
• Record the refrigerant added and recovered, and leave you the record for the equipment

Who is legally allowed to open the refrigerant circuit

Refrigerant work is not like changing a socket or bleeding a radiator. GOV.UK states plainly that it is against the law to work with F gas without the correct qualifications, and that this applies to the individual doing the work even when they are employed by someone else.

There are four certificate categories. Category 1 covers all activities including installation, servicing, leak checking, recovery and decommissioning. Categories 2 and 3 are limited by the amount of gas in the system, and category 4 only permits leak checking without breaking into the circuit.

Separately, the company — including a sole trader — must hold F gas company certification to install, repair, maintain or decommission stationary air conditioning belonging to someone else.

• Ask for the engineer's F gas category before booking, not after.
• Ask for the company's F gas certification number; sole traders need one too.
• Expect a record of refrigerant added or recovered to be left with you.
• Treat an offer of a routine annual top-up with no leak test as a warning sign.