Electrics and gas
An air-source heat pump is bolted to the flank wall. Does the survey decide permitted development, or that every room is on that system?
No. The survey does not decide permitted development for the air-source heat pump bolted to the flank wall, and it does not decide that every room is on that system. It records the unit it could see: the outdoor box, its position, and the pipes in view. Permitted development is a planning question, not a finding from a visual inspection. Which rooms the system heats is inside the house, at emitters and controls the survey has not proved. Ask the solicitor about planning, and a heat-pump engineer about what the unit actually serves.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
The outdoor unit is the part a surveyor can stand beside. Bolts, brackets, pipe insulation and where the case sits on the flank wall are visual points. They are not a planning decision. Permitted development depends on rules and on the history of the installation, which are not measured by looking at a fan coil on a wall. Indoors, a heat pump can serve all the rooms or only some of them, and the outdoor box does not answer that.
Split the follow-up. Ask the solicitor what planning or building papers exist for the unit on the flank, without expecting the survey to rule on them. Ask a heat-pump engineer which circuits and emitters they can confirm. Do not assume every radiator or floor loop is connected because the outdoor unit looks large. Keep the survey sentence as the record of the box that was bolted there.
What should you ask your surveyor?
- What of the air-source unit did you see: the case, the bracket, the pipes, or all three?
- Did any indoor cylinder, controller or emitter look linked to it from where you stood?
- Were the pipes lagged where they entered the wall, or was that hidden?
What are the typical next steps?
- Ask the solicitor about planning papers for the flank-wall unit.
- Ask a heat-pump engineer what the system actually serves.
- Do not read the outdoor unit as proof that every room is connected.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If the fan was running, is every room on the heat pump?
No. A running fan shows the outdoor unit was operating. It does not list the rooms connected indoors or prove the whole house is on it.
Can the surveyor grant or refuse permitted development?
No. Permitted development is not a decision the surveyor can grant or refuse. Ask the solicitor what papers exist for the flank-wall unit.