Electrics and gas
The outdoor weather sensor sits in the shade of a porch. Has the survey decided the control curve is wrong?
No. Shade on the outdoor weather sensor has not decided that the control curve is wrong. The sensor is there to read outside conditions for the heat pump controls. Sitting under a porch may make that reading differ from air in the sun, but the survey did not log temperatures, did not test the curve, and did not measure output. The visit recorded where the sensor is fixed. It has not decided the controls are faulty or that the curve should be rewritten.
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?
A weather sensor in a sheltered pocket can read a cooler, stiller air than the rest of the garden. That is a siting observation, not a graph. The control curve is the relationship the controller uses between outside conditions and what it asks of the heat pump. Changing it, or calling it wrong, needs data the visit did not take. The survey must not invent temperatures, and it has not. Position is all that was established.
Ask a heating engineer if you want the sensor position and the curve reviewed against how the system is actually operating. The survey does not decide grant eligibility and does not issue a building-regulations certificate. Tell your solicitor the sensor was seen in porch shade and that no control test was done. Do not tell a lender the heat pump is inefficient because of that shade. Inefficiency was not measured.
What should you ask your surveyor?
- Was the sensor only recorded as sitting in porch shade?
- Did the visit log any temperatures or test the curve?
- Has efficiency been left unmeasured?
What are the typical next steps?
- Record the shaded sensor without calling the curve wrong.
- Ask a heating engineer if the siting needs a proper review.
- Do not tell a lender the heat pump was proved inefficient.
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
Could the porch shade still be worth moving later?
It might be, but this survey has not decided that. A specialist can judge whether the pocket of shade is skewing the control. The report only places the sensor under the porch. It does not order a move, and it does not show that a move would change how the house is heated.
Does holiday or off mode on a controller settle the curve?
No. A mode on a screen is a setting at the time of the visit, not a test of the weather curve. The shaded sensor and the controller are separate observations. Neither one was used to plot or to correct the curve. Both can sit in the report without proving a fault.