• Flues in ceiling voids
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Flues in ceiling voids research project

An invitation to join a new reserach project

BSRIA is putting together a group of interested parties from industry, boiler and flue manufacturers, which also may include the relevant UK associations such as NHBC, APHC, FETA, CLG -communities for local government, HSE, Gas Safe, Westminster City Council, BSI, The Chartered Institute of Environmental Health and house builders such as Barratt Homes and Bellway homes, to look at the issue of flues that are installed in ceiling voids and the implication of carbon monoxide poisoning.
 

About the research

BSRIA has been involved in a number of investigations on site where the installation of flues particularly in ceiling voids have been called into question regarding the integrity (gas tightness) and safety of this type of installation. This type of installation is used in heating systems with a room sealed boiler that uses a twin flue arrangement which connects to an outside wall. A separate flue is used to provide the combustion air to the appliance and the other flue is used to discharge the products of combustion to the outside of the building. Installations of this type are mainly in flats and apartment blocks where the potentially long flue lengths are concealed within a ceiling void. Many installations use polypropylene push-fit connections, which are easy to assemble and save on the installation costs. However recently there have been several instances where the integrity of the flue, in particular at the section joints, has been reported to come apart during operation and several years after the installation has been completed.

The UK Building Regulations (Part J) recently introduced the installation of inspections hatches for inspection of the joints.But the industry may consider more robust regulations for in situ testing of flues in ceiling voids to assess its integrity during the construction phase of any building and before commissioning of the boiler is carried out. Setting up of competent persons scheme for carrying out the inspection and testing is also necessary as part of any future regulations.

What will be covered

The problem currently faced by construction companies and the gas installers is that there is currently no industry standard for in situ testing of flues. The information in the Gas Safe Bulletin T200 is limited. Part of the scope of the research work will therefore be to develop a robust test methodology which will be pilot tested in a number of buildings (10 to 20) particularly blocks of flats during the construction phase, especially those with long flue runs ( 8 metres) where the flue is installed in a ceiling void. Other aspects of the project will look at the following issues:

• Construction techniques where the flue passes through a wall
• The depth of the ceiling void to facilitate the required fall of the flue for condensing boiler applications
• Fixing supports for flues
• Application of remote video monitoring for difficult access installations
• Inappropriate size/location of access
• Flues routed either horizontally or vertically through neighbouring properties
• Incorrect material used for flue
• Flues longer than manufacturers allowances when including bends etc
• Flues for condensing appliances not running back to the appliance
• Incorrect flue support used - such as builders strap banding - resulting in flues dipping in the middle
• Incorrect location of support (not at joints)
• No accommodation for expansion and contraction of flue system resulting in flues separating
• Incorrect termination of air ducts within roof spaces
• Leakage of condensate from flue joints
• Damage to flue systems from other trades
• Providing appropriate fire stopping whilst still allowing for expansion and contraction of the flue system.
• Correctly installed flue systems, with correct support, accommodation for movement, inspection hatches etc, that have been confirmed as being correctly installed by the appliance manufacturer, still coming apart.

The full detailed scope of the project is yet to be decided between the project participants and BSRIA

It is proposed that BSRIA should lead the development of this work. This would entail liaising with industry members (boilers and flue manufacturers) as well as with those organisations concerned with gas safety. The methodology would be rigorously tested in the lab at BSRIA to ensure that all aspects were valid and that the procedure could be clearly followed on site. Finally, the methodology and the research report would be offered to the industry as a BSRIA published good practice document.

To express your interest in joining this research and participating as a sponsor and contributor, please email: test@bsria.co.uk

About BSRIA's research expertise

BSRIA's Microclimate, Test and Refrigeration Group has a growing research capability that undertakes a range of consultancy and research projects in the building services sector covering both domestic and commercial buildings. This also includes our capabilities to carry out forensic type investigations in the laboratory and on site.

View our recently completed research projects:

Energy efficient pumping systems - Guide
Air supply for combustion appliances in airtight homes - Report

Contact:

BSRIA Test & Certification

Tel:       +44 (0)1344 465600
Email:   test@bsria.co.uk