If you’ve never had air conditioning fitted, it’s natural to picture days of disruption, walls opened up and a house full of dust. The reality is usually much gentler: a single-room system is typically installed in a day, and the messiest moment is one hole drilled through an outside wall. Here’s the whole journey, start to finish, so nothing on the day comes as a surprise.
Step one: the enquiry
You get in touch with an installer (or a matching service does it for you), describe your home and which rooms you want cooled, and they’ll usually ask a few quick questions — house or flat, roughly when it was built, where the room sits in the house, and whether there’s an obvious spot outside for the outdoor unit. A photo or two of the room and the outside wall often saves a visit. From there they’ll book a survey, typically within a week or so.
The survey — what a good surveyor actually checks
This is the most important visit of the whole process, and it’s where good installers earn their keep. A proper surveyor will:
- Size the room properly — measuring the space, noting window area and which way it faces, insulation and what the room is used for. Oversized units short-cycle; undersized ones run flat out and disappoint.
- Agree the indoor unit position — usually high on a wall, throwing air across the room rather than straight at where you sit or sleep.
- Find a home for the outdoor unit — somewhere with airflow, sensible access for servicing, and ideally not directly under a bedroom window or hard against a neighbour’s fence.
- Plan the pipe route — the shorter and straighter the run between indoor and outdoor units, the tidier and cheaper the job.
- Think about condensate — cooling produces water, which needs to drain somewhere sensible by gravity or a small pump.
- Check your electrics — the system needs its own supply from the consumer unit. If your board is old or full, they should say so now, not on install day. Our guide on whether your home’s electrics can handle air conditioning covers what that involves.
A surveyor who breezes in, glances at the room and quotes off the top of their head is a warning sign. Detail at this stage predicts detail on the day.
The quote
A good quote names the exact equipment (brand and model, not just “a wall-mounted split”), states the pipe run and where everything goes, includes electrical work, and says whether making good — filling and painting around the pipework — is in or out. Prices vary with the property, the pipe run and the kit, so gather more than one quote and compare like with like; our cost guide explains the typical ranges and what moves the number. If one quote comes in far below the others, ask what’s been left out.
Install day, step by step
For a single room, expect the crew for most of a day. It usually runs like this:
- Protection down — dust sheets in the work area; a tidy firm treats your home like theirs.
- Indoor unit mounted — a bracket goes on the wall in the agreed spot, checked level, and the unit hangs on it.
- The core drill — one hole, roughly the size of a tin of beans, drilled through the outside wall behind or beside the unit. It’s loud for a few minutes, then done. This carries the refrigerant pipes, cable and condensate drain outside.
- Outdoor unit fixed — on a ground-level base or wall brackets, with anti-vibration mounts so it hums rather than rattles.
- Pipework connected — the copper pipes are run (usually in white plastic trunking outside), connected at both ends, and the electrical supply wired in.
- Vacuum and test — the crucial bit. The engineer pulls a deep vacuum on the pipework to remove air and moisture, then holds it to prove there are no leaks, before releasing refrigerant into the system. Skipping or rushing this is what causes systems to fail early — it’s a good sign if your installer takes their time here.
- Commissioning — the system is run in both cooling and heating (a modern split heats as well as cools), temperatures are checked, and the engineer confirms it’s performing as it should.
A multi-split serving three or four rooms is the same process repeated, typically over two to three days.
Making good and handover
Before they leave, the installers should seal the wall hole inside and out, tidy the trunking, clear up and walk you through the remote or app — modes, timers, and the one habit worth forming: set a sensible temperature and leave it alone. Ask where the filters are and how to rinse them; it takes a couple of minutes and is worth doing regularly in summer.
That’s also the limit of sensible DIY. Rinsing the filters and wiping the casing is yours; everything else — the refrigerant circuit, the sealed electrical parts, anything that means removing a panel — is a job for an F-Gas certified engineer, both legally and practically. If the system ever stops cooling, ices up or trips the electrics, switch it off and call one rather than opening anything up.
The paperwork you should receive
By law, anyone handling refrigerant must be F-Gas certified — it’s not optional, and a legitimate installer will show their certification without being asked twice. After the job you should receive commissioning records (including the pressure test and vacuum readings), the manufacturer’s warranty registration, an electrical certificate for the new circuit, and details of the refrigerant type and charge in your system. Keep it all — you’ll want it for warranty claims, servicing and when you eventually sell the house.
After the install
Running costs are usually lower than people fear — our running costs guide puts real numbers on it. An annual service keeps the warranty valid and the system working efficiently.
Where Coolhouse fits in
Most of the stress in this process comes from not knowing whether the person quoting you is any good. Coolhouse matches you with one vetted, F-Gas certified installer for your area rather than selling your details to five. If you’d like a starting figure before anyone visits, get a quick estimate — it takes a couple of minutes and commits you to nothing.