A UK split install needs an adult on site who can approve a route change, not only someone who can open the door. Core positions, trunking across a front elevation, and where the outdoor unit stands are decisions with a cost and a planning consequence. A neighbour, a teenager or a dog walker with a key cannot sign those off. The F-gas engineer can explain the options. They should not invent your consent.
The adult who can say yes to a new hole
Surveys are good and walls still surprise people: a lintel, a flue, a cable, a tank on the other side. The team then offers a different hole, a longer trunking run or another bracket height. That needs a yes or a no from the owner or from someone the owner has named, with a phone number that is answered. If you will be at work, book the day when you can be there for the first hour and the handover, or give written authority to a named adult who understands the outdoor position you already accepted. Authority to make tea is not authority to move the condenser onto the party wall. If a different person will take handover, name them too.
At the start the team marks the bracket and the hole. That is the last cheap moment to say the indoor unit is over the wrong chair. At the end you need the model numbers, the isolator, a filter demo and the commissioning paperwork. A person who arrived only to unlock cannot check those, and the van will have left. If two owners disagree, decide before the drill. Installers should not referee a couple in the hallway. Write the agreed elevation on the quote so the person at home is not hearing the plan for the first time.
Flats, tenants and a housemate who hates trunking
In a flat, the leaseholder or a representative with the freeholder's written consent should be the voice on site. A tenant who booked the job without the landlord can put the engineer in an impossible spot once the hole is proposed. Show the consent, do not summarise it. Renters need that consent before the day, not during the drilling. The F-gas engineer can explain the options. They should not invent your consent.
Shared houses need one decision maker. A housemate who hates trunking on their bedroom wall will say so when the core bit appears. Sort that the week before. Planning Portal rules on the outdoor unit do not pause because the right person was on a train.
Frequently asked questions
Can I leave a key with a neighbour?
Only if that neighbour can approve a route change and stay for handover, and you have said so in writing. Unlocking the door is not enough.
Do both owners need to be there?
One named adult with authority is enough, if the other has already agreed the outdoor position and the trunking. Do not leave a live disagreement for install morning.
What if I can only be there at lunchtime?
Tell the installer. Many teams can mark up, pause for your yes, then drill. They cannot invent consent while you are unreachable.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
Related guides
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.