If this summer is the problem, cool the main bedroom and leave the rest of the house for a later decision. One matched split, sized for that room with the door shut, is a finished job. A multi-split 'so you can add rooms later' is the wrong purchase when the later rooms have not passed a pipe, height and outdoor-spot check. Survey the bedroom first. An F-gas certified company installs the pair. You can add another room next year if a real route exists.
The bedroom as a finished summer job
Sleep is when a hot house actually costs you. A modest reverse-cycle wall unit, often in the 2.0 to 3.5 kW class after a survey of a typical main bedroom, holds the night without trying to condition the landing. The kilowatt is the survey's figure, not a rule. South-facing glazing and a room in the roof need their own look. Keep the air off the pillows. A low fan and a steady setpoint beat a unit that blasts and stops. The outdoor unit should not sit on the other side of the same window you are trying to sleep beside, unless anti-vibration mounts and a careful bracket still leave it quiet. If they will not, use another elevation or a ground stand.
Spare ports, diaries and a deposit against one pair
Two bedrooms on the same wall can share a small multi-split when the survey shows the runs work. A vague plan to do the landing, the office and the spare room is not that survey. Fit the main bedroom as a single pair and keep the receipt, the model codes and the data plates for whatever comes next.
Hot weather fills installers' diaries. The way to be ready is a survey now, model codes on the quote, and a deposit only against that pair. Skipping the visit to get something in before the weekend is how the drain and the outdoor spot are invented on the day.
As a 2026 illustration, one ordinary bedroom split is often in the low thousands of pounds including VAT when the wall is simple and the board has room for a circuit. Scaffold, a pump or a board change moves it. Say this is the main bedroom only, with heating if you want it. A photo of the bed relative to the wall, the outside elevation and the consumer unit lets the firm price that room. Ask for the indoor and outdoor model codes, low-fan sound, pipe length and condensate route. Mention any lease or conservation constraint so the timetable includes consent, not only the install day.
Scaffold, the board and a lawful outdoor slot
In England, check Planning Portal conditions for the outdoor unit before you assume a summer slot is also a lawful slot. A finished single room is a complete job. The landing is only partly cooled, and only while the bedroom door is open.
Frequently asked questions
Will one bedroom unit cool the landing as well?
Only while the door is open, and only partly. With the door shut it cools the bedroom, which is the point of this job.
Should I wait until I can afford the whole house?
Not if nights are the problem and the bedroom has a lawful outdoor route. A finished single room is better than a whole-house drawing that never gets surveyed.
Can a portable do the bedroom for one summer?
It is louder beside the bed and it needs a window hose. A fixed split is the better sleep install when the outdoor unit can be sited properly.
Should I buy a larger outdoor unit with spare ports for later rooms?
The spare port is only useful if next year's room is inside the pipe length and height limits, and if one lawful outdoor spot can carry both. If you have not surveyed that room, you are paying for capacity and noise you may never connect.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.