On a corner plot the decision is which wall is lawful and which wall is quiet, because they are often not the same wall. Two elevations can front a highway. A side that feels private to you can still be the street the Planning Portal conditions care about. Pick the outdoor spot from those limits and from bedroom windows, then run the pipes to it. F-gas certification covers the circuit. It does not choose the wall.
A flank that still fronts the other road
A corner house can present a front door to one street and a long flank to another. Owners often call the flank the side and assume it is free of highway rules. In England, air source heat pump conditions on the Planning Portal include limits that bite on walls facing a highway. Read the current conditions against both roads before you treat either wall as permitted development.
The garden wall, away from both pavements, is often the candidate that survives that reading. It may be the noisier wall for a neighbour, or the quieter one. Measure it rather than assuming. Name which wall faces which road.
Bedroom windows, a second box and a longer pipe run
The lawful wall can still hum at your bedroom or at the neighbour who sits on the boundary. Ask for sound power and the night figure, and for anti-vibration mounts. A flank wall close to the next house reflects noise down the passage. Keep the unit off bedroom windows.
One outdoor unit is easier to place than two. If you need a second condenser, permitted development unit counts on houses that are not detached can fall outside the Planning Portal allowance. Hedge that by reading the current Class G summary rather than assuming a second box is free.
A short pipe run to an unlawful wall is a wasted install. Trunking can take a longer route to a rear or garden position if the lids stay removable for leaks. The indoor rooms still need a proper throw. Do not put the indoor unit in a corner solely because the corner faces the garden. Do not order the outdoor unit until the wall is chosen.
Certification after the wall is already chosen
The company that joints the refrigerant circuit needs F-gas certification. Energy Saving Trust's air-to-air description is the heating and cooling behaviour. It is not a planning consent. The quiet wall may face a highway. The hidden wall may be on the neighbour's boundary. Say which is which.
Frequently asked questions
Is the side of a corner plot automatically allowed?
No. That side may front the other road. Read the Planning Portal conditions for highway-facing units before you treat it as permitted development.
Should I pick the quietest wall and assume planning will follow?
Pick a wall that can pass both tests. The quiet wall may face a highway. The hidden wall may be on the neighbour's boundary. Say which is which.
Does F-gas certification settle the wall?
No. It covers the refrigerant work. The wall is a planning and noise decision. Read the Planning Portal, then use a certified company for the circuit.
Can the outdoor unit be ordered before the wall is chosen?
No. Do not order the outdoor unit until the wall is chosen. A short pipe run to an unlawful wall is a wasted install. Read the Planning Portal highway and boundary limits against both roads first.
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.