Electrics and gas
The tundish on an unvented cylinder was dry and the discharge route was not traced outside. What outlet is unverified?
The outlet that is unverified is the discharge to the outside. The tundish on the unvented cylinder was dry, and the route from that tundish was not traced out of the building. A dry tundish means no water was running through it on the day. It does not show where the pipe ends, or whether that end is a safe, visible outlet. The survey has recorded the dry tundish and the untraced route. It has not verified the outlet.
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 tundish is the open point in the safety discharge pipe where you can see if water is being let go by a valve on an unvented cylinder. Dry on the day means the valves were not discharging during the visit. It does not prove the valves, the cylinder, or the pipe beyond. If the pipe disappears into a wall and was not followed outside, the outlet is simply unknown. The home survey did not commission the cylinder and did not test the safety devices.
Ask a heating engineer who is competent on unvented cylinders to trace the discharge to its outlet and to check the safety devices. Tell the solicitor the tundish was dry and the outside end was not verified. Do not read dryness as a pass for the cylinder. Keep any installation certificate for the vessel separate from this incomplete route. The outside end is the outlet that stays unverified.
What should you ask your surveyor?
- Was the tundish dry for the whole of the visit?
- How far did you follow the discharge pipe before you stopped?
- Which outside outlet, if any, did you fail to find?
What are the typical next steps?
- Ask an engineer competent on unvented cylinders to trace the discharge outlet.
- Tell the solicitor the tundish was dry and the outside end was not verified.
- Do not read a dry tundish as a pass for the cylinder.
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 tundish is dry, are the safety valves proved sound?
No. A dry tundish does not prove the safety valves are sound. It proves they were not running water at the moment of the visit. The survey did not test them, and the outlet beyond the tundish was not traced. Dryness is not a service of the unvented cylinder.
Was the unvented cylinder itself tested, or only the dry tundish seen?
No. The pressure vessel itself was not inspected as a test. The note is about a dry tundish and a discharge route that was not followed outside. Condition of the cylinder shell, the controls, and the expansion arrangement was not established by seeing a dry tundish. That is a different inspection.