Before the van leaves, you should hold the indoor and outdoor model numbers, an F-gas certificate or commissioning sheet, and proof that the warranty has been registered or a date when it will be. You should have seen the isolator, watched a filter come out, and know where condensate goes. A remote left on the side without that paperwork is an incomplete handover. The refrigerant work is only finished when those records exist.
Model plates and the commissioning sheet
Write down, or photograph, the indoor model and serial, and the outdoor model and serial. The quote's marketing name is not enough when a board fails in three years. The commissioning sheet should show that the system was vacuumed, the electrics checked, and the drains tested, in the company's wording.
F-gas rules apply to the company that handles the refrigerant. Keep their certificate details with the invoice. If they say the certificate will be emailed, ask which address and by when. A verbal promise on the doorstep is hard to snag later. If the papers are still missing after the day, keep photos of both data plates and a list of what did not arrive. A later check needs those. Do not send a second company in blind.
The isolator, the drain and a setpoint you can live with
Ask to be shown the isolator and what it actually switches off. You need that spot after a storm if the casing is damaged, and you should not be hunting for it in the dark. Ask where condensate leaves. Have them set a normal cooling setpoint and a fan speed you can live with, not 16C. The unit delivers its kilowatts. A lower number does not make the first hour colder in any useful way, and it can ice a coil. Doors shut and windows closed is the habit to learn in the first week, while they are still there to explain it.
Registration, not a sticker on the casing
Many manufacturers only honour the longer warranty if the installer registers the install. Ask who does that, and ask for the confirmation. Your own receipt matters if there is a dispute about who attended. Energy Saving Trust's air-to-air pages describe the equipment. They do not replace the commissioning record.
Leave with a note of the service they expect, often at the end of the first cooling season rather than the next day, unless the warranty text says otherwise. You want those records before the final payment.
Frequently asked questions
Is a commissioning sheet the same as an F-gas certificate?
They are related and they are not identical. You want the company's F-gas credentials and a record of this install: models, tests and the drain. Ask for both if they are separate documents.
What if they leave before showing the filter?
Ask them back to the doorway and have them show you. The filter is ordinary maintenance. You should see the arrow and how it seats before you need it in a month.
When should the warranty show as registered?
On the day, or on a date they write down. Chase that date. A long warranty that was never registered is a short warranty.
What if a condensate pump is fitted?
Ask them to show it before they leave. A pump in an empty house is a leak you will not see, which is a reason to know the route now.
What if making good is still outstanding?
If making good or a return for paint is outstanding, that goes on a written list before you pay the balance. Do not treat a remote on the side as a finished handover.
Core buying guides
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Sources and further reading
How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.