Electrics and gas
Nothing on the visit sampled a thermal store, opened the blending valve or tested hot water the taps were not run long enough to judge. What has to stay undecided?
The outlet temperature, the blending valve and the condition of the thermal store have to stay undecided. Nothing on the visit sampled the store, opened the blending valve, or ran the taps long enough to judge the hot water. A thermal store holds heat, and the blender mixes it down before it reaches a tap. The survey could name the equipment if it was visible. It has not decided that the store is hot enough, that the blender is sticking, or that the water at the tap is acceptable. Those points were not tested.
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 thermal store is a vessel of heated water used to raise the domestic supply through a coil or a plate, and a blending valve then limits how hot the outlet is. If the taps are only cracked open, you learn little about stored heat or about a valve that may pass too hot. The surveyor did not open the valve and did not sample the store. What is written is the limit of the visit. It is not a temperature. The mechanism can be described. Its behaviour cannot.
Ask a heating engineer to run the taps long enough and to check the blending valve. If the heat source is gas, that appliance work belongs with a Gas Safe registered engineer. Tell the solicitor the hot water was not judged, so no one should say the store passed or failed. The survey did not sample the vessel and did not decide it needs replacing. A short run at a basin is not the missing test. Keep the store, the valve and the unjudged taps as open points.
What should you ask your surveyor?
- How long were the hot taps run, and at which fittings?
- Was the blending valve visible, and was it left unopened?
- Did you see leaks or corrosion on the store, or only the intact case?
What are the typical next steps?
- Leave outlet temperature and the blending valve undecided.
- Ask a heating engineer to run the taps and check the valve.
- Tell the solicitor the store was not sampled and not passed.
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
Is a thermal store the same as an ordinary hot-water cylinder?
Not quite. A thermal store holds heat for the system and usually heats tap water indirectly, with a blending valve on the outlet. An ordinary cylinder stores the water you actually draw. The survey did not open the valve and did not run the taps long enough to judge. Naming the store is not a test of either arrangement.
Can you tell the stored water is wholesome because the tap ran clear?
No. A short clear run was not even achieved as a proper test, because the taps were not run long enough to judge. Nothing was sampled. Colour, if it had been seen, would still not be a hygiene test. The survey has not decided the store is clean or fouled. That stays undecided until an engineer inspects it.