The short answer
A single-room split is usually installed in half a day to a full day, while a multi-split serving several rooms typically takes two days or more. The time depends on the pipe-run length, access, whether new electrical work is needed, and the commissioning — the leak test and vacuum that an F-Gas-certified engineer must complete cannot be rushed. A pre-install survey is separate and is what makes the install day run to schedule.
Knowing how long the job takes helps you plan access, time off and where you will be while the work happens. Most homeowners are surprised it can be done in a day for a single room, and equally surprised that the commissioning at the end is not optional or quick. This guide explains the realistic timings and what pushes them up or down. It is general information; your installer’s survey will give a firm schedule for your property.
Timing at a glance
- Single split Half a day to one day
- Multi-split Two days or more
- Survey Separate, before the install
- Biggest variable Pipe run & access
- Commissioning Leak test + vacuum, not rushed
- Electrical Adds time if new circuit needed
Single split: half a day to a day
For a single room with a straightforward pipe route and good access, an experienced two-person team commonly completes a split installation in half a day to a full day. That covers mounting the indoor unit, fixing the outdoor condenser, drilling the core hole, running and dressing the pipework and cabling, and the commissioning at the end. If a new dedicated electrical circuit has to be run from the consumer unit, add time for that work. The figure assumes the survey is already done and the position agreed — see air con installation explained for the full sequence behind the timeline.
Multi-split and larger jobs: two days or more
A multi-split connects several indoor units to one outdoor unit, which means more pipe runs, more cabling, more trunking to dress and more commissioning checks. These jobs typically run to two days or more, and a whole-house or commercial system longer still. Difficult routes — multiple floors, long runs, awkward outdoor access requiring scaffolding — extend the timeline further. If you are weighing the configuration up, read split vs multi-split air con to understand why the head count drives the time.
| System | Typical install time |
|---|---|
| Plug-in portable | Minutes (no installation) |
| Single split | Half a day to one day |
| Two- or three-room multi-split | Around two days |
| Whole-house / large multi-split | Several days |
Why commissioning cannot be rushed
The last part of the day is the commissioning, and it is the part you should never let an installer skip to save time. The engineer pressure-tests the pipework for leaks, then evacuates it with a vacuum pump to remove air and moisture before releasing the refrigerant. Vacuuming in particular takes a set amount of time to do properly — cutting it short leaves moisture in the system that forms acids and causes early compressor failure. This stage is legally restricted to F-Gas-certified engineers, and it is the difference between a system that lasts and one that fails early.
What pushes the time up or down
- Pipe-run length and route: long or multi-floor runs add hours of pipework and dressing.
- Access: scaffolding or restricted outdoor access slows the whole job.
- Electrical work: a new dedicated circuit, notified under Part P, adds time on the day.
- Number of indoor units: each extra head adds pipework and commissioning.
- Surface and weather: hard brickwork, render and wet weather can slow outdoor work.
Plan around the survey
The survey happens before install day and is what keeps the schedule honest — it confirms the route, the electrical position and the planning constraints so nothing is discovered mid-job. A firm quoting an install time without surveying is guessing, and that guess is what causes jobs to overrun. Once surveyed, you will get a realistic schedule, and you can plan access for the right number of days. For the electrical element that most often extends the timeline, read air con electrical requirements.
It also helps to know what your part of the timeline looks like. On install day you need to give the team clear access to the room, the wall where the outdoor unit will be fixed, and the consumer unit if a new circuit is being run. Power may be interrupted briefly while the circuit is connected and tested. Once commissioning is complete, the engineer demonstrates the controls and hands over the warranty and commissioning paperwork — budget a little time at the end for that handover rather than expecting to disappear the moment the unit blows cold. A single split usually leaves you with a working system by the same evening; a larger job spreads that across the agreed number of days, which is exactly why the survey-led schedule matters.
Get a scheduled survey
Ask your installer to survey first and quote a firm install duration, so you can plan access and time for the work and the commissioning.
Frequently asked questions
How long does a single split take to install?
With good access and a straightforward pipe route, a single-room split is commonly fitted in half a day to a full day, plus extra time if a new electrical circuit is needed.
How long does a multi-split installation take?
Multi-split systems serving several rooms typically take two days or more because of the additional pipe runs, cabling and commissioning. Whole-house systems can take several days.
Why does commissioning take time?
The engineer must pressure-test for leaks and vacuum the pipework to remove moisture before releasing refrigerant. Proper evacuation takes a set time and cannot be rushed without risking early failure.
Does a survey count as part of the install?
No. The survey is a separate visit before installation. It confirms the route, electrics and planning so the install day runs to schedule.
Sources & further reading
- Daikin — installation and commissioning technical guidance
- Mitsubishi Electric — split and multi-split installation guidance
- gov.uk — Fluorinated Greenhouse Gases Regulations 2015 (commissioning)
- gov.uk — Building Regulations: Approved Document P (electrical work)
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.