Where should the outdoor AC unit go? A siting guide for UK homes
Nine out of ten noise complaints and planning problems come down to one decision: where the outdoor unit goes. Get it right at survey stage and everything downstream is easy.
The rules you have to meet
- Not on a wall or roof facing a highway if it fronts a road (permitted development, Class G)
- Not above the highest part of the roof
- No more than 0.6 m³ in volume
- No more than 42 dB(A) at 1m from a neighbouring habitable window
- One unit per dwelling under permitted development; extra units need a planning application
- Listed buildings and conservation areas: check with the council first — permitted development is usually restricted
Good places to put it
- Side return or flank wall, away from bedroom windows on both sides
- Rear elevation behind a garage or utility, at ground level on a plinth
- A shaded spot — direct all-day sun costs efficiency
- Somewhere reachable for annual servicing without scaffolding
Places that cause problems
- Directly under a neighbour's bedroom window
- In a narrow passage between two houses — sound bounces and amplifies
- Boxed into an enclosed cupboard or shed with no airflow
- On a hollow stud wall or thin render — it drums
- Anywhere the condensate drain will run across a footpath and freeze
Clearances the manufacturer expects
| Side | Minimum clearance |
|---|---|
| Front (air discharge) | 500 mm |
| Rear (air intake) | 100 mm |
| Service side | 300 mm |
| Above | 500 mm |
| Below (ground clearance) | 100 mm |
Tighter than this and the unit recirculates its own hot air — louder, less efficient, shorter life, and often a void warranty.
Screening it without strangling it
Louvred timber screens are fine as long as they're at least 300mm clear of the intake and open at the top. Solid boxes are not — they trap heat and, counter-intuitively, make the unit louder because the compressor has to work harder. If a unit must be hidden, tell us at survey and we'll size the screen properly.
FAQ
How far from the boundary can an AC unit be?
There's no fixed boundary distance in permitted development — the controlling limit is 42 dB(A) at 1m from a neighbouring habitable window, which we calculate at survey.
Can the outdoor unit go on the front of the house?
Not under permitted development if the wall fronts a highway. A rear or flank wall position is normally used instead, or you apply for planning permission.
Can I put the condenser in a shed or cupboard?
No. It needs free airflow — an enclosed space causes recirculation, higher noise, poor efficiency and often invalidates the warranty. A louvred screen with clearance is the correct solution.
How far can the outdoor unit be from the indoor unit?
Most domestic systems allow 15–25m of pipe run, so there's usually plenty of freedom to place the condenser somewhere sensible.
Ready for a real price on your home?
Free home survey, fixed written quote, F-Gas certified installers across the West Midlands. 60-second form or WhatsApp us a photo.