Air Conditioning Commissioning Checklist (Split & Multi-Split)

A commissioning checklist for split and multi-split air conditioning: installation checks, pressure test, evacuation, refrigerant charge, run tests, records and handover.

By Max Tuleberg · Founder, Vento · Last updated 25 October 2026

Founder of Vento. Worked on the tools before building the software.

Commissioning proves the system is tight, dry, correctly charged and performing — and leaves a record that it was. Use this checklist for split and multi-split installs, and always follow the manufacturer's installation manual for the figures: test pressure, vacuum level, additional charge and operating ranges vary by product.

1. Installation checks

☐ Indoor units level and secure; clearances as per the manual.
☐ Outdoor unit secure, level, with airflow clearance and anti-vibration mounts where specified.
☐ Pipe runs within the manufacturer's maximum length and height difference.
☐ Pipework insulated, supported and protected; flare or brazed joints made to the manual.
☐ Condensate falls correctly; pump fitted and tested where needed.
☐ Electrical supply, isolation and interconnecting cable correct and tested.

2. Pressure test

☐ Pipework pressure tested with oxygen-free nitrogen to the manufacturer's test pressure.
☐ Pressure held for the specified time with no drop; joints leak-checked.
☐ Test pressure and duration recorded.

3. Evacuation

☐ Evacuated with a vacuum pump to the manufacturer's level, measured with a micron gauge.
☐ Standing vacuum hold carried out to prove no leaks or moisture.
☐ Vacuum reached and hold result recorded.

4. Refrigerant

☐ Service valves opened to release the factory charge.
☐ Additional charge added by weight for pipe length beyond the pre-charged length, per the manual.
☐ Refrigerant type and total charge recorded on the unit label and your records.
☐ CO₂e worked out (charge × GWP ÷ 1,000) to see whether F-Gas leak checks apply — use the leak-check interval calculator.

5. Run tests

☐ System run in cooling and heating; all indoor units and modes tested.
☐ Operating pressures and temperatures within the manufacturer's ranges.
☐ Air on / air off temperatures measured at each indoor unit.
☐ Controls, timers and any Wi-Fi control set up and working.
☐ No unusual noise, vibration or water.

6. Handover

☐ Customer shown how to use the controls and clean the filters.
☐ Manuals, warranty registration and the commissioning record handed over.
☐ Servicing recommended and, where needed for the warranty, booked.
☐ Site left clean; all making good completed as quoted.

Vento keeps an F-Gas register of every system you install — refrigerant, charge and CO₂e, with systems under 5 tonnes marked exempt — and schedules the next leak check whenever you log one. See F-Gas compliance in Vento.

This guide is general information for UK installers, not legal or regulatory advice. Always check the current regulations and manufacturer instructions for your specific job.

Frequently asked questions

What does commissioning an air conditioning system involve?

Checking the installation, pressure testing the pipework with oxygen-free nitrogen, evacuating it to the manufacturer's vacuum level and proving it holds, releasing or adjusting the refrigerant charge for the pipe length, then running the system in cooling and heating to confirm it performs as it should — and recording all of it.

What vacuum should an air conditioning system be pulled to?

To the level the manufacturer specifies, measured with a micron gauge. A figure below 500 microns, followed by a standing hold to prove there's no leak or moisture, is common practice — but the installation manual for the unit is the requirement.

What records should be kept after commissioning?

The test pressure and duration, the vacuum reached and hold result, the refrigerant type and total charge (including any added for pipe length), operating readings, and the engineer's F-Gas certificate number. For systems at or above 5 tonnes CO₂e, the F-Gas logbook requirements also apply.