Many English homes can install an air source heat pump under permitted development, but the exact location, unit size, property type and sound assessment all matter.
In England, many installations are permitted development
Permitted development means you can install without a separate planning application if every relevant condition is met. The current Planning Portal guidance includes size limits of 1.5 cubic metres for a house and 0.6 cubic metres for a flat, limits on the number of units, restrictions around listed buildings and scheduled monuments, and a sound assessment under MCS 020(a).
The rules are more generous for detached houses than flats or other houses. The former blanket one-metre boundary restriction was removed in 2025. That change does not make every position acceptable: noise, siting, heritage and local restrictions still need checking.
The sound test is about the neighbour's assessment position
MCS 020(a) uses a calculated sound level at an assessment position, with a 37 dB(A) limit for permitted development. That is not a claim that the machine itself must be 37 dB(A) at one metre. Distance, walls, reflections and the chosen model all affect the calculation.
Ask the installer to show you the completed sound assessment before finalising the outdoor unit location. Moving the unit on the plan can change both its sound impact and the installation cost.
When to ask the council
Check with the local planning authority if your home is listed, in a conservation area or subject to an Article 4 direction, or if the proposed position is unusual. Flats and roofs have extra restrictions. Planning permission may also be needed if any permitted development condition cannot be met.
This article describes England. Wales, Scotland and Northern Ireland have their own planning rules. Your installer should identify the applicable rules for your address, and the planning authority gives the final view on whether an application is required.
Keep the evidence with your installation records
Ask for the site plan, sound assessment, model details and the installer's written explanation of which permitted development conditions apply. If the local planning authority confirms a special restriction, keep that response too. These records make future questions about the unit much easier to answer.
Planning is only one check. The installer may also need to confirm building regulations, electrical work and any leasehold or landlord consent. Ask who is responsible for each approval before you pay a deposit.
A note about the numbers
Prices, grants and tariffs can change. The dated figures above come from the linked sources and are examples unless explicitly described as a published average. Your installer should assess your property before giving a final design or quotation.