F-Gas leak testing

Does it apply to you?

It depends on one figure, and it is straightforward to establish.

1. Find the nameplate on the outdoor unit. It carries the refrigerant type and the charge in kilograms.
2. Multiply the charge by that refrigerant’s global warming potential, and divide by 1000. That gives CO2e in tonnes.
3. Compare against the current thresholds. Below the lowest, there is no mandatory periodic leak checking. Above it, checking is required at an interval that shortens as CO2e rises.

Because refrigerant GWPs vary by a large factor, two physically similar systems can have completely different obligations. It is worth doing the arithmetic rather than assuming.

Where it does apply domestically

• Larger multi-split systems, where the combined charge is substantial.
• VRF in a large house, which is uncommon domestically and does happen.
• Older systems on high-GWP refrigerant, which reach a threshold at a much smaller physical charge than a modern R32 system would.
• Home offices and outbuildings with substantial cooling, where the installation is effectively commercial in scale.
• Any refrigeration – a wine room, a cold store, a garage chiller – which counts exactly as air conditioning does.

For commercial premises the obligations are more extensive and the duty sits explicitly on the equipment operator – see F-Gas compliance.

What a leak check involves

It is not a visual inspection and it is not the same as a service.

1. Carried out by a qualified personWorking for a certified company. Both are required – employing qualified engineers is not sufficient on its own.
2. Using an appropriate methodA calibrated electronic leak detector, or an indirect method based on system parameters where the standards permit it.
3. Covering the parts prone to leakageJoints, valves, seals, flare connections, service ports, and anywhere subject to vibration.
4. RecordedDate, method, result and who carried it out – including checks that found nothing.
5. Repair without undue delay where a leak is foundAnd a re-check within the defined period afterwards to verify the repair worked.

A maintenance visit does not automatically constitute a leak check, and conflating the two is a common source of gaps. Both should happen and both should be recorded separately – see air conditioning servicing.

Why a system that needs topping up has a problem

A refrigeration circuit is sealed. There is no such thing as routine refrigerant consumption. If a system is low, refrigerant has escaped, and it will keep escaping.

• Topping up without repairing is not permitted, and deliberate release is an offence.
• It is money evaporating. On a high-GWP refrigerant, increasingly expensive money as the phase-down progresses – see the refrigerant phase-down.
• Performance degrades before the system fails, so you are running inefficiently in the meantime.
• Low charge damages the compressor, because refrigerant carries the oil that lubricates it.
• The leak is usually findable. Most split system leaks are at flare connections, which is a workmanship issue from installation showing up years later.

So the right response to a system that is not cooling as well as it did is to find out whether it is low and why, rather than to add gas and carry on.

Records

Where a system is above the threshold, records must be kept covering the refrigerant type and quantity installed, any added or recovered and why, who did the work, the dates and results of every check, and the measures taken at end of life.

Two practical points that apply even below the threshold, because they are useful rather than merely required:

1. Keep your own copy, not just your contractor’s. If you change contractor, the history is yours and you are entitled to it.
2. Record the charge at installation, including any additional refrigerant added for long pipe runs. Without an accurate charge figure you cannot calculate CO2e, and reconstructing it later is awkward.

See what an F-Gas logbook must contain.