Electrics and gas
A combi boiler is mounted on an outside wall in a cupboard open to the weather. What flue and what frost protection were not tested?
Neither the flue nor the frost protection was tested. The combi sits on an outside wall in a cupboard open to the weather, so the survey can describe that exposed position. It cannot say the flue discharges safely, that the terminal is clear, or that any frost protection works. The visit did not include a Gas Safe inspection. Cold-weather performance of the case and the pipe was not demonstrated by looking at an open cupboard.
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 combination boiler on an external wall still needs a flue that terminates properly and a case that can live with the weather. A cupboard open to the outside is not an indoor compartment with a planned vent. Rain and frost can reach the case and the controls. The survey saw the arrangement. It did not test the flue or operate a frost stat. Seeing the boiler is not a commissioning test.
Ask a Gas Safe engineer to inspect the flue and to say whether the open cupboard needs frost protection or a different enclosure. Tell the solicitor the home survey has not tested either point. Do not tell an insurer the boiler was passed because it is a known model on an outside wall. The report records the exposed location only, not a weather trial.
What should you ask your surveyor?
- What of the flue terminal could you see from the open cupboard?
- Was any frost protection present, and was it tested?
- Did you leave both the flue and the frost protection untested?
What are the typical next steps?
- Treat the flue and the frost protection as untested.
- Ask a Gas Safe engineer to inspect the exposed combi.
- Do not describe the open cupboard as a completed weather test.
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 boiler lit, has the flue been accepted?
No. Lighting shows a flame or a fan response on the day, not a flue inspection. The survey did not test the terminal, the route or the discharge. An appliance can fire in an open cupboard and still have an unchecked flue. Gas safety is a separate inspection from the home survey.
Does a cover over the top count as frost protection?
Only if it is actually frost protection and it works, which was not tested. The survey saw a cupboard open to the weather and did not operate a frost stat or prove the case is protected. A board over the boiler is not that test. Cold-weather performance stays outside this visit.