How Long Does Air Conditioning Installation Take?
A single wall-mounted split takes half a day to a day to install; a multi-split serving two or three rooms takes one to two days; a ducted whole-house system takes three to seven days and is usually done during a refurbishment. The longer wait is the one before the engineers arrive — typically one to four weeks from accepting a quote, and longer in a heatwave. Here is the full timeline from enquiry to cool air, and how to keep it short.
Installation time by system type
| System | Time on site | Engineers | What takes the time |
|---|---|---|---|
| Single split (one indoor, one outdoor) | Half a day – 1 day | 1–2 | Core drilling, bracket and outdoor unit, pipe run and trunking, electrics, pressure test, vacuum, commissioning |
| Multi-split (2–3 indoor units) | 1 – 2 days | 2 | Several pipe runs to one outdoor unit; longer evacuation; each indoor unit commissioned |
| Multi-split (4–5 indoor units) | 2 – 3 days | 2–3 | As above, plus routing through lofts or voids and more making good |
| Ducted whole-house | 3 – 7 days | 2–3 + builder's trades | Ductwork in voids, grilles, plasterboarding and decoration, controls, balancing |
| Like-for-like replacement of an existing split | Half a day | 1–2 | Refrigerant recovery, swap units, re-use or replace pipework, recommission |
Typical durations for a standard house or flat with reasonable access; awkward pipe runs, high outdoor positions and new circuits add hours rather than days. Your quote should state the installer's estimate.
The timeline from enquiry to cool air
- Enquiry and matching (same day – 2 days). You describe the job at /quote; Air Con Surrey matches you with vetted, F-Gas certified local engineers who contact you to arrange a survey.
- Site survey (within about a week). 30–60 minutes: room sizes and heat gains, unit positions, pipe route, condensate drainage, electrical supply, planning considerations.
- Written quote (1 – 3 days after). Itemised — see our quote comparison guide. Getting three quotes can add a week, and is worth it.
- Acceptance and booking (1 – 4 weeks' lead time). Equipment is ordered — popular ranges are usually in UK stock, some premium or designer models take longer — and a date set. In spring and autumn one to two weeks is common; in July and August during a heatwave, four weeks or more is normal because every installer's diary fills at once.
- Installation (half a day – 7 days, per the table).
- Commissioning and handover (the last hour). Pressure test and vacuum complete, charge recorded, system run in both modes, controls and app set up, commissioning sheet and warranty registration handed over.
End to end: two to five weeks outside the summer peak; four to eight weeks if you start in a heatwave. If you want air conditioning for next summer, the calm months are September to April.
What to prepare before the engineers arrive
- Clear the wall where the indoor unit is going and the area beneath it; cover furniture — core drilling produces dust.
- Clear the outdoor-unit position and the route to it; unlock side gates; move cars if a tower or scaffold is coming.
- Confirm the pipe route agreed at survey so there is no debate on the day about where the trunking runs.
- Electrics: make the consumer unit accessible if a new circuit is being added; expect the power off briefly.
- Permissions: in a flat, conservation area or listed building, have consents or freeholder permission in hand — see our planning guide.
- Neighbours: a word in advance about a day of drilling and an outdoor unit saves friction later.
- Wi-Fi password ready if the unit has app control — commissioning includes pairing it.
How disruptive is it?
For a wall-mounted split: modest. The noisy part is core-drilling a 65–80 mm hole through the external wall for the pipes, a few minutes per unit. The rest is bracket fixing, pipework, trunking and quiet electrical and commissioning work under dust sheets; you can normally use the rest of the house as usual and the room again that evening. A multi-split adds another day of the same. A ducted installation is building work — ceilings opened, ducts run, plasterboard and decoration made good — best done within a wider refurbishment or while the house is empty. Pipework is usually boxed in white trunking outside and hidden in voids inside where possible; concealing it in walls is a decorating job to plan for.
Commissioning: why the engineer should not rush it
Commissioning decides the system's longevity. The circuit is pressure-tested with nitrogen to prove it is tight, then a vacuum pump removes air and moisture — a proper deep vacuum can take 30–60 minutes on its own. Only then is refrigerant released from the outdoor unit (with any extra charge weighed in for long runs). The engineer runs the system in both modes, checks temperatures and currents, sets up the controller and app, and completes a commissioning sheet you should keep. An installer who packs up 20 minutes after connecting the pipes has skipped something. For the paperwork, see our F-Gas certification guide.
FAQs
Sources & methodology
- Installation durations and lead times: typical figures reported by installing engineers in the Air Con Surrey network for domestic split, multi-split and ducted systems, 2026.
- Commissioning procedure (nitrogen pressure test, evacuation, charge, run test): manufacturer installation manuals and UK F-Gas good-practice guidance.
- Planning: Town and Country Planning (General Permitted Development) (England) Order 2015 as amended.
Start the clock: get matched with local engineers
The quickest route to a date in the diary is a survey this week. Air Con Surrey is a free matching service — we'll match you with vetted, F-Gas certified engineers near you who can survey, quote and book you in.