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Flues concealed in voids

What is the problem?

Some properties, mainly flats and apartments, have been built with appliance flue systems which cannot be inspected because they are hidden behind walls or ceilings. This makes it difficult to identify any safety concerns with the flue system and could be dangerous. It affects a type of flue system that is termed ‘room- sealed fanned draught’ and does not apply to ‘open flues’ such as brick chimneys serving gas fires.

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  • Flue system: the pipe (or pipes) that take fumes away from the gas appliance and also provides fresh air for the gas to burn correctly.
  • Void: a space above the ceiling or behind a wall where the flue is located.
  • Room-sealed fanned draught appliance: is one which is sealed from the room in which it is located. The flue

    system takes fumes away from the appliance and also provides fresh air for the gas to burn correctly.

Gas Safe registered engineers need to be able to see the flue system as part of essential safety checks whenever the appliance is worked on. A flue system in poor condition, combined with an appliance 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 your appliance is situated on an outside wall, it is unlikely you have the type of flue system that is affected. Alternatively, if your engineer can see all of the flue system, you will not need to take any further action in relation to this matter.

What is the background?

In October 2008, following a fatal carbon monoxide (CO) poisoning incident, the Health and Safety Executive (HSE) in Great Britain issued a Safety Alert concerning certain gas appliance flues in voids. It explained that if appropriate action was not taken, there was a risk of further serious incidents occurring if there was a defect in a concealed flue system. In December 2010, following a period of review and consultation by industry, revised guidance was published. Subsequently the HSE in GB and the HSE in Northern Ireland (HSENI) took the decision to issue an updated Safety Notice.

The Safety Notice has revised guidance which includes advice and requirements for Gas Safe registered businesses, builders and home warranty providers. It aims to help them bring the safety concern to the attention of affected residents, landlords and managing agents so that suspect installations can be addressed.

What properties are affected?

Visit:  for information.

Did you know?

Although the HSE Safety Notices apply to GB and NI, similar requirements apply in the Isle of Man and Guernsey.

In properties where a gas appliance is located away from external walls, its flue system is more likely to run through the ceiling or wall void or be boxed-in. These situations are more likely, but not exclusively, to be encountered in flats and apartments built since about 2000.

What needs to be done if my property is affected?

If you think that your property may be affected by this issue, the first thing to do is contact a Gas Safe registered engineer to carry out a safety check of the appliance and flue. To find a Gas Safe registered engineer go to or call us on 0800 408 5500.

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

CO alarms are not an alternative to being able to see the flue system 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, however, that inspection hatches are fitted as soon as you are able to do so. From 1 January 2013, any registered gas engineer will ask your permission to turn the appliance off and formally advise you not to use it until inspection hatches have been fitted in appropriate places.

If the property is one to two years old you should contact your builder for help in getting inspection hatches fitted. If the property is between two to 10 years old you should contact your Building Warranty Provider for help.

Further Guidance

For more information, FAQs and list of the main home warranty providers visit:

For further information about this gas safety concern, visit the HSE or HSENI website and view the HSE/HSENI Safety Notice, which also includes a number of frequently asked questions.

HSE Safety Alert: HSE Safety Notice:

Update to the HSE 2008 Safety Alert

HSENI Safety Notice:

Remember, whenever having any gas work carried out, always use a Gas Safe registered engineer holding the relevant qualifications for working on your gas appliance. To find or check a Gas Safe registered engineer go to or call our free helpline on 0800 408 550


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