Electrics and gas
A three-port valve beside the heat pump was not turned. What of the hot-water path is still unknown?
The hot-water path through that three-port valve is still unknown. The valve beside the heat pump was not turned, so the survey did not see whether it sends heated water to the cylinder, to the heating circuit, or to both. A three-port valve is a diverter, and a still actuator does not prove the port it would open. Efficiency of the heat pump was not measured. The unmoved valve is a limit of the inspection, not a pass of the hot-water route.
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?
In a typical layout the valve's three ports connect the heat source, the hot-water cylinder and the space-heating circuit. Which port is open decides where the hot water goes at that moment. If the head is not turned, the internal shoe stays where it was, and the surveyor cannot watch a change of route. Pipes either side can be identified only as pipes. A warm cylinder or a cold radiator on one afternoon does not map the valve. The path remains a diagram nobody operated.
The Boiler Upgrade Scheme is a grant route in England and Wales toward a heat pump or biomass boiler, not in Scotland or Northern Ireland. This survey does not decide eligibility and quotes no grant figure. Approved Document L is energy-performance guidance for building work, and the visit does not issue a building-regulations certificate. Ask an installer to demonstrate the valve if you need the path known. Tell a lender the diverter was not operated.
What should you ask your surveyor?
- Which port the valve would open for hot water is still unknown?
- Was the actuator turned so a change of route could be seen?
- Has heat-pump efficiency been measured from the still valve?
What are the typical next steps?
- Treat the hot-water route through the valve as unproved.
- Ask an installer to demonstrate the valve if the path must be known.
- Do not read the still valve as a pass of the cylinder circuit.
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
Does a still valve count as an efficiency test of the pump?
No. Efficiency needs the machine running under known conditions, with temperatures taken. Leaving the three-port valve unmoved does not create those readings. The survey identified a valve beside the heat pump and did not turn it. Performance of the pump stays unmeasured. The hot-water path through the valve stays unknown as well.
Will this visit decide whether a grant is available for the pump?
No. The Boiler Upgrade Scheme is a grant route in England and Wales toward a heat pump or biomass boiler, not in Scotland or Northern Ireland. The survey does not decide eligibility and must not quote a grant figure. An unmoved valve is an inspection limit. It is not an application and not a grant decision.