What Happens During a Split AC Installation?

A standard split AC installation process UK installers follow takes between three and eight hours, depending on how many rooms you are cooling and whether your electrics need upgrading. Expect one to two hours of drilling and noise, concentrated in short bursts, with the rest of the day spent on quieter work like pipework, wiring, and testing. Most homeowners stay in the house the whole time. Nobody needs to move out, and the mess is contained to dust sheets around the drill points, not a full building project.

The survey visit: what happens before installation day

Before any installer picks up a drill, a reputable one comes to look at the property first. A proper survey visit takes 30 to 60 minutes and covers everything the installer needs to know to give an accurate quote and plan the actual job.

What a good installer checks during the survey

The surveyor should assess where the indoor units will sit, the pipe run between indoor and outdoor units, where the outdoor condenser will be mounted, whether your electrical supply can take the extra load, the type of wall construction (this affects how long drilling takes and what tools are needed), and what making good will involve once the work is done.

Installation day, step by step

The exact order varies slightly between installers, but a typical single or multi-split installation follows this sequence.

1. The installer arrives and confirms unit placement and pipe routing with you before starting any work.
2. The indoor unit bracket is mounted on the wall, usually with two fixings. This takes 15 to 30 minutes.
3. A hole is drilled through the external wall for the refrigerant pipe, electrical cable, and condensate drain, typically 65 to 75mm across. This is the noisiest part of the day and lasts 10 to 20 minutes per hole.
4. The outdoor condenser is mounted, either on wall brackets, a ground plate, or a flat roof frame, depending on your property.
5. Refrigerant pipes are run between the two units, insulated, and either clipped to the wall or chased into it.
6. The electrical connection is made. A dedicated circuit from your consumer unit is standard practice. If your consumer unit needs modifying, this adds time and may need a separate electrician.
7. The refrigerant is charged. This step must be handled by an F-Gas certified engineer and takes 30 to 60 minutes.
8. The system is commissioned and tested. The installer runs it through every mode, checks temperatures, verifies the drainage works, and shows you how the controls operate.
9. Making good takes place, meaning any plastering and painting around the wall penetrations, either done there and then if it is included in your quote, or left for you to arrange separately.

How long it actually takes

These are working estimates based on standard domestic installations, not a guarantee for every property. A Victorian solid wall house with awkward pipe routing will generally take longer than a modern cavity wall new build.

How disruptive it is

Drilling is loud, but only for short bursts rather than all day. Dust is produced at the drill points, and a competent installer will use dust sheets to contain it. Everything else, including the pipework, wiring, and commissioning, is quiet work. Most homeowners can carry on with normal life in other rooms while it happens. Keep children and pets away from the immediate work area while drilling is underway, and clear a path to your consumer unit in advance.

What the finished installation looks like

Indoor unit

A white rectangular unit mounted high on the wall, usually 80 to 100cm wide and 25 to 30cm tall. The pipe connection exits through the wall behind or beside it. In a good installation, the pipework is concealed in trunking or chased into the wall rather than left exposed and visible.

Outdoor unit

A box shaped condenser fixed to the external wall or standing on the ground, typically 80 to 90cm wide and 55 to 65cm tall. It produces a low hum when running, and should not be audible inside the house at normal conversation volume.

Making good: what to check before the installer leaves

Making good means repairing the wall around the pipe penetration, filling, skimming, and repainting so there is no visible hole surrounded by filler. This is the detail many installers quietly leave out of the quote. Before you accept a quote, ask directly whether making good is included or whether it is a separate cost you will need to arrange yourself. If your quote already feels high before you factor this in, our guide on whether your air conditioning quote is too high is worth reading alongside this one. Fixings, sealants, and materials for making good after installation are available at Professional Building Supplies.

What to do on installation day

Clear the area around where the indoor and outdoor units will go, and make sure the installer has access to your consumer unit. Stay reachable during the day. The installer will need you to confirm decisions like exact pipe routing, unit height, and condensate drain direction as the work happens, not after the fact.

The bottom line

A split AC installation process UK wide is a day of focused, moderately noisy work, not a building project you need to plan your life around. Get a proper survey first, ask about making good before you sign anything, and expect somewhere between three hours and two days depending on how many rooms you are cooling. If an installer skips the survey or dodges the making good question, take that as your answer about how the rest of the job will go.

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