Where Should Your Outdoor AC Unit Go?

The outdoor unit — the condenser — is the part of an air conditioning system that does the heavy lifting, and where you put it affects three things: how well the system performs, how much noise it makes, and whether you need planning permission. Get it right and you'll barely notice the unit is there. Get it wrong and you risk an inefficient system, an annoyed neighbour, or a planning headache.

A good installer will assess positioning during the survey, balancing airflow, pipe runs, access and noise. This is a core part of any professional installation, not an afterthought.

The condenser rejects heat to the outside air, so it needs clear, unobstructed airflow. Cramming it into a tight alley, behind dense planting or under a low overhang forces it to recirculate its own warm air, which makes it work harder, costs more to run and shortens its life.

As a rule of thumb, leave clear space at the front (where air is blown out) and around the sides. Avoid sun-traps where possible — a shaded north or east wall is often kinder than a baking south-facing one. Good positioning is one of the simplest ways to keep your running costs down over the life of the system.

Modern inverter units are quiet, but they're not silent, so position is everything for keeping the peace. Avoid siting the unit directly under or opposite a bedroom window — yours or a neighbour's — and keep it away from boundary fences where sound can reflect and amplify.

This isn't just courtesy: it's tied to the rules. To qualify as permitted development, the unit generally needs to sit at least a metre from your boundary and keep noise to around 42 dB(A) at a neighbour's nearest window, in line with the MCS 020 standard. A well-chosen position is what keeps you compliant — see our planning permission guide for the full detail.

The closer the outdoor unit is to the indoor unit(s), the shorter the refrigerant pipework — which means a tidier install, slightly better efficiency and usually a lower price. Long, winding pipe runs add cost and can reduce performance, so the ideal spot is often the external wall nearest your main indoor unit.

Don't forget servicing access either. Your unit will need an annual check, so it must be reachable safely. A condenser buried behind a locked extension or three storeys up with no access makes servicing and maintenance and any future repairs harder and more expensive.

The most popular spots are on an external wall (mounted on brackets), at ground level on a small plinth or feet, or on a flat roof. Each has trade-offs: wall-mounting saves ground space but can transmit a little vibration; ground-mounting is easy to service but uses garden space; roof-mounting hides the unit but costs more to install and access.

If you're in a flat, a conservation area or a listed building, your options are more constrained and you'll likely need consent regardless of position — so speak to a specialist early. We handle plenty of these in Surrey, where conservation stock is common, and we'll find the best compliant position for your property.