Split AC installation in the UK: permissions, process and costs

Installed air conditioning used to be a luxury-home rarity in Britain. Rising summer temperatures are changing that fast — but the installation process is still a minefield of half-answers. Here's the straight version.

The legal foundations

Split systems contain fluorinated refrigerant. Under the UK's F-Gas Regulation, anyone installing, servicing or decommissioning them must hold F-Gas certification (individual and, for companies, organisational certification such as REFCOM). This is a legal requirement. An uncertified "mate who does aircon" isn't just risky — the installation is unlawful, may void the manufacturer warranty, and will surface at conveyancing when you sell.

At Coolhaven every installation partner is vetted for F-Gas certification and insurance before they see a single job. Ask for certification numbers from any installer; good ones volunteer them.

Do you need permission?

• Detached/semi/terraced house you own: usually fine under permitted development, provided the outdoor unit meets siting rules (size limits, distance from boundaries, not on the principal elevation facing a highway in many cases). Conservation areas and listed buildings: talk to the council first, always.
• Flat (leasehold): you almost certainly need freeholder/management company consent to fix an outdoor unit to the building. Get it in writing before paying anyone.
• Rented home: landlord's written consent, full stop. (Landlords: tenanted-property cooling is exactly what our landlord programme exists for.)
• New-builds: check your management company covenants — some restrict external plant.

None of this is a reason to give up; it's a reason to survey properly before committing money.

What a real survey covers

Anyone quoting a fixed price without a survey is guessing with your money. A proper survey checks:

1. Heat load — room dimensions, glazing area and orientation, insulation, occupancy. (Our calculator gives a preliminary estimate; the survey makes it real.)
2. Indoor unit position — airflow across the room, not into the sofa; condensate drainage route.
3. Outdoor unit position — structural fixing, noise to neighbours, service access, and the pipe run (shorter is better and cheaper).
4. Electrics — most single splits run off a dedicated spur; your consumer unit needs the capacity.
5. Permissions — everything in the section above.

What it should cost

UK market reality for a quality single-room split, professionally installed: roughly £1,200–£2,500 all-in, driven by unit quality (budget vs Daikin/Mitsubishi-tier), pipe run length and access difficulty. Multi-split (one outdoor, several indoor units) typically £2,500–£5,000+. If a quote is dramatically below this range, ask what's been skipped — usually the answer is the survey, the certification, or both.

Running costs are the pleasant surprise: modern units deliver 3–4 kWh of cooling per kWh of electricity, so holding a bedroom comfortable through a hot night costs pence, not pounds. Most are heat pumps, so they also heat efficiently in winter.

Timeline expectations

Outside heatwaves: survey within days, installation 1–3 weeks later, half a day to a day on site for a single split. During a heatwave: everything doubles or worse, because every installer's phone is melting. This lead time is exactly why we built priority reservations — the queue for surveys forms before the temperature does.

The Coolhaven process

Reserve priority (£10, refundable) → we confirm partner coverage for your postcode → survey booked with a certified partner → written quote with final pricing → you decide, with your £10 credited. Every step before the quote costs you nothing you can't get back — that's deliberate.