Survey the fabric before you choose a wall unit. An older UK house often has solid walls, a chimney breast that is not a free wall, a consumer unit with no spare way, and no obvious place for condensate. The first split should be one room with a lawful outdoor spot, not a whole-house multi-split drawn over limits you have not measured. Listed buildings and conservation areas add a consent step. An F-gas certified company installs the pair once those limits are known.
Solid brick, stone and the first hole
Many houses built before the 1920s are solid brick or stone. The hole is a core drill through the full thickness, sleeved and sealed, and the finish inside and out has to be made good. That is not a cavity-wall detail and it does not involve cavity ties, because there is no cavity. Thickness, flint, timber lintels and lime plaster are survey facts, not extras to discover with the drill running. An internal timber stud with no noggin is a poor bracket. The external wall, when you can use it, keeps the pipe short. Confirm solid wall, cavity or timber before the quote is fixed, and price making good the real finish. State the approximate age of the house, and attach photos of the indoor wall, the outside elevation, the consumer unit and any chimney on that wall.
A full board and a missing gully
Older consumer units are often full, rewireable, or tucked in a cupboard that no longer meets clearance rules. The first split may wait on an electrician. Condensate is the other quiet problem. A solid-wall parlour may have no soil pipe on that elevation. Gravity to a gully is still the aim. A pump is the fallback, with a route that does not track across a lime-plastered ceiling. The survey should pick one before the unit is ordered.
Listed fabric, the rear yard and the first room
In England, check Planning Portal conditions before you put an outdoor unit on a front or side wall that the street sees. Listed houses need listed building consent for the fixture and the hole, which is separate from permitted development. A conservation area can restrict the elevation even when the house itself is not listed. Pipe length and height still rule out a multi-split that tries to reach every bedroom from the only rear yard you are allowed to use. Cool the room you shut. Add another pair later if a second spot exists. As a 2026 illustration, the first simple split is often in the low thousands including VAT, and the board, the solid-wall finish or consent drawings are what push it up. Ask for one surveyed room, with model codes, wall type, making good, drain method and the electrical scope written out. Say you do not want a multi-split until pipe length, height and a single lawful outdoor spot have been measured. An older house will often take a normal wall split after that survey. The machine is ordinary. The fabric and the consent are the variables.
Frequently asked questions
Will an older house take a normal wall split?
Often yes, after a survey of the wall, the drain and the board. The machine is ordinary. The fabric and the consent are the variables.
Do I need to rewire the house first?
Not always. You do need a safe way to supply a dedicated circuit. If the board cannot provide one, that electrical job comes before switch-on.
Should the first job be every bedroom?
No, unless each run stays inside the pipe and height limits and one lawful outdoor spot can serve them. Start with the room that is actually too hot.
Can the indoor unit hang on the chimney breast?
Do not hang the indoor unit on a chimney breast until someone has confirmed it is dead and safe to drill. A chimney breast looks like a solid place for a bracket and often hides flues.
Can the first split run from a socket behind the sofa?
No. A dedicated circuit for a 230 V unit is the ordinary ask. Do not plan to run it from a socket behind the sofa.
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.