Electrics and gas
Does a carbon monoxide alarm on the wall mean the survey tested the flue?
No. An alarm is a warning device. It is not a flue-flow test, a gas tightness test or a service. A surveyor who sees an alarm, or who does not see one, should not be read as having certified the appliance. HSE still expects gas work to be done by a Gas Safe registered engineer.
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?
Alarms save lives when appliances or flues fail. Their presence does not tell you the flue is clear, the ventilation is enough, or the heat exchanger is sound. Their absence is something an engineer may comment on when they service the appliance. It is not, by itself, a RICS condition rating. The Level 3 description says services are inspected visually and not tested for safety.
If the survey has also said the flue looks damaged, blocked or spilling, that is the sentence to give a Gas Safe engineer, whether or not an alarm is fitted. Do not “test” an appliance by holding a handheld alarm near it on a viewing. Ask for a proper inspection if you need one before you commit.
What should you ask your surveyor?
- Did you see an alarm, and did you test any appliance?
- What, if anything, looked wrong with the flue from the room or from outside?
- Is the alarm comment separate from the limitation that services were not tested?
What are the typical next steps?
- Do not remove the batteries to silence a chirp and then forget it. Tell the seller.
- If the flue is questioned, instruct a Gas Safe engineer before you use the appliance.
- Do not deduct a flue repair from the price because an alarm was missing. Get the appliance inspected first.
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 an alarm required in every house?
Requirements depend on the work and the fuel, and they change. The survey is not the building-regulations certificate. Ask the engineer and, if work is planned, the building-control route.
Does a beeping alarm mean gas is leaking?
It means the alarm is sounding. Leave the appliance alone and get a Gas Safe engineer. Do not treat the survey as the emergency response.