Tel 07802 758166

Perfect Heating And Plumbing A Guide to Concealed Boiler Flues Within Ducts

It has become fashionable amongst builders of flats and apartments to install modern gas boilers with long ducts for the flues and air intakes concealed behind ceilings or within the fabric of the buildings. This leads to a problem that doesn’t bother the builders, but it DOES affect any Gas Installer working on the appliance at a later date. It’s turning into quite a problem for either Gas Installers or for their customers, depending on the attitude to risk of the Gas installer, and I predict there will be a few high-profile court cases as a result soon.

The problem is this: Any gas installer working on a gas appliance is required under regulation 26(7) of the Gas Safety (Installation and Use) Regulations 1998 to “examine the effectiveness of any flue” and “the supply of combustion air”. To comply with this regulation in practice we need to inspect the whole of the flue length for integrity and make sure there are no design and/or workmanship flaws, and do the same to the air intake duct. In many properties, newly-built in particular, the flue and air ducts are concealed behind ceilings or within the fabric of the building meaning this safety-check cannot be done. The Gas Installer is obliged to ‘condemn’ the installation.

Now the chances of any individual flue duct or air intake being faulty are quite small, so many Gas Installers take the view that they’ll take a chance and declare the appliance ‘safe’ despite being unable to inspect the flue and air duct. In the vast majority of cases they will probably be right! But when the Gas Installer works on large numbers of appliances then the risk of him/her ‘passing’ a genuinely dangerous flue becomes significant and the consequences can be catastrophic, up to and including death of the occupier(s).

A flue duct that has come apart behind a ceiling void for example will be discharging products of combustion onto the space behind the ceiling and these potentially dangerous flue gases will be contaminating the air in the house/flat. If the boiler then starts producing carbon monoxide the occupants of the property will be at serious risk of CO poisoning and injury or death. (Speculation is that this was the cause of death in the Oxford tragedy involving two British Gas subcontractors who worked on a Range PowerMax boiler.)

When a flue or air intake duct is concealed and cannot be inspected the appliance is, strictly speaking, categorised “At Risk” and should be turned off and a Warning Notice issued. Very tough if you called a boiler technician in to repair the boiler in your smart new-build flat and he says ‘no’. Sadly this is the policy all Gas Installers need to follow to avoid risk to their customers and personal prosecution with a potential prison sentence should such an event occur.

The most common boilers to be installed with concealed flues and air intakes are the Gledhill Gulfstream, the Range PowerMax, the Potterton PowerMax, Keston C40 and C55 and the Ideal Istor. Between them these four appliances are fitted in most gas-fired new-build flats. Installations in new-build houses are less of a problem – the ducts are not usually concealed in the same way as in flats.


Boiler Flues in Ceiling Spaces

Important advice for consumers who have flues which run in ceiling spaces

Some properties, mainly flats and apartments, have been built with boiler flues which cannot be inspected because they are hidden behind walls or ceilings. The boiler flues that this information relates to are connected to room-sealed fan assisted boilers.  If you live in one of these homes then please read on for more information so you know what to do.

Gas Safe registered engineers need to be able to see the flue − which take fumes away from the boiler − as part of essential safety checks whenever the boiler is worked on. A flue in poor condition, combined with a boiler that is not working properly, could put you and your family in danger fromcarbon monoxide poisoning, which can cause death or serious injury.

If your boiler is situated on an outside wall, it is unlikely you have this type of flue. Alternatively, if your engineer can see all of the flue, you will not need to take any further action in relation to this matter.

If you do have a boiler where all, or part of, the flue cannot be seen, you, or your landlord, will need to arrange for inspection hatches to be fitted. This does not mean that your flue system is suddenly unsafe. As long as the boiler passes a series of safety checks − including having audible carbon monoxide alarms fitted − it can be used normally for the time being.

Carbon monoxide alarms are not an alternative to being able to see the flue and you will still need to have inspection hatches fitted. You have until 31 December 2012 for this work to be completed. It is recommended that inspection hatches are fitted as soon as you are able to do so. From 1 January 2013, any Gas Safe registered engineer will turn the boiler off, with your permission and formally advise you not to use it until inspection hatches have been fitted in appropriate places.

Although most of the affected boiler and flue systems are relatively new (installed since 2000), the risk of faults leading to the release of carbon monoxide increases as the system gets older, especially if it is not serviced regularly. It is important that you have your gas appliances serviced annually.

More information can be found on the HSE website here and here upon the Gas Safe Website.

You need to take action now

If your property is less than two years old then contact your builder. If your property is between two and ten years old contact your home warranty provider, as you may be covered by them if there are defects in the flue. A list of the main home warranty providers is shown below. If your property is 10 years or older you should contact a Gas Safe registered engineer.

If you are a tenant, it is the responsibility of your landlord to ensure that inspection hatches are installed and that the boiler and flue are checked every year.

If you have any questions please see the list of Frequently Asked Questions. If you have a specific enquiry e.g. around building warranties please direct it one of the groups listed below.

For any additional enquiries not answered through these routes please send questions  and it will be dealt with by a member of the group
To find a Gas Safe registered engineer in your area:

List of main home warranty providers

This advice has been developed by the Flues in Voids cross-industry team. It is made up of representatives of Gas Safe Register, house builders, home warranty providers, registered gas engineers, appliance manufacturers (including HHIC) and others and assisted by HSE, to provide clear communication to industry and consumers around the issue of flues being located in voids which do not allow inspection.