If you live in a property that has a boiler flue which cannot be inspected because it is hidden behind a wall or ceiling, you need to install an inspection hatch.
As part of essential safety checks, gas engineers need to be able to see the flue that takes fumes away from the boiler. A flue in poor condition, combined with a boiler that is not working properly, could put you and your family in danger from carbon monoxide poisoning, which can cause death or serious injury.
If you have a boiler where the flue is completely or partly hidden, the owner of your property (whether yourself or a landlord) will need to arrange for inspection hatches or a carbon monoxide detection system to be fitted.
Carbon monoxide alarms should not be used an alternative to your Gas Safe registered engineer being able to see the flue and if you can't see the flue, you will still need to have hatches or a detection system fitted as soon as possible. From 1st January 2013, registered engineers are obligated to turn off the gas supply to any boiler systems which haven't had hatches fitted in the appropriate places.