The Chimney Sweeps Hetas
1. CHIMNEYS AND FLUESThe details on the factory made chimney and flue products listed in this section have been provided with the help of the British Flue and Chimney Manufacturers Association. The current status of each product has been declared to HETAS by the manufacturer.
Many of the products listed are covered by recognised independent test certification. Where a claim is made that the product is manufactured to a British Standard or meets Building Regulations 2000 for England and Wales by satisfying the recommendations of the current (1st April 2002) edition of Approved Document J or otherwise by demonstration of compliance, this claim is the responsibility of, and should be confirmed with, the manufacturer prior to purchase.
It should be understood by purchasers and specifiers that a claim recorded in the Approval Status column as "Manufacturer claims to BS xxxx", although coming within the Trade Descriptions Act, is a claim of the manufacturer alone and not endorsed by HETAS.
Where the claim in the Approval Status column quotes a BSI Kitemark, BBA, BSRIA, Wimlas, CSTB, HETAS or TÜV certificate number this is an indication that the product has been independently type tested and approved by a body entitled to engage in third party certification and product monitoring. Publication in this Guide does not endorse such manufacturers' claims.
2. SELECTION OF A CHIMNEY OR FLUE SYSTEM 1. The flue size of the system and arrangement are determined by the type of appliance to be used and its location. The siting of a chimney outlet should minimise the effect of emissions on the dwelling itself and on neighbouring buildings.
Whatever chimney arrangement or products used must satisfy Building Regulations and the recommendations of British Standard BS EN 15287: 2007 for masonry chimneys and flue pipes, or BS EN 12391-1:2003 Chimneys-Execution standard for metal chimneys – Part 1: Chimneys for non-roomsealed heating appliances
2(i). The UK Building Regulations Approved Document J 2010 Edition specifies that chimneys built using products meeting the requirements of European product standards should result in a chimney whose performance is at least equal to that corresponding to the designation T400 N2 D 3 Gxx where xx is the necessary separation from combustible materials.
Although BS EN 1443:2003 also allows chimneys serving an open fire burning only wood to have a corrosion resistance class 2 HETAS Ltd considers that all chimneys serving appliances burning solid fuel should have the designation class 3. Products having the designation W for condensate resistance class meet the requirement . A product with an Oxx designation, not having been subjected to a soot fire test , is not accepted for use in the UK.
2(ii). The temperature designation T400 implies a mean flue gas temperature of no more than 400°C during the nominal output (normal running) of the appliance.
If it is demonstrated that the appliance operates with a lower flue gas temperature during its normal operation, e.g. new high efficiency appliances including those which may be condensing, and those burning biomass, then the temperature designation may be reduced to that specified by the appliance manufacturer.
However, the chimney shall still have a resistance to soot fire designation ‘G’. Chimneys serving condensing appliances specifically designed to operate with flue gas temperatures below the flue gas dew point shall have the designation ‘W’ instead of ‘D’, and provision made for the disposal of any condensate generated in the chimney.
The size of the chimney (height and flue diameter) shall be according to BS EN 15287-1 clause NA.4.2.3. This specifies minimum dimensions to be used where the flue gas characteristics of the appliance serving the chimney are not available.
Where sufficient information is available from the appliance manufacturer the flue size for a specified chimney construction may be calculated using the calculation methods given in BS EN 13384-1. BS EN 13384-3 may be used to provide tables or graphs of chimney dimensions for a variety of appliances and chimney constructions.
NOTE: Attention is drawn to the UK National Annex to BS EN 15287-1 that gives recommendations for the construction of chimneys based on UK practice previously identified in BS 6461-1 and BS EN 12391-1 (which replaced BS 7566). These standards are now withdrawn.
3. Flue sizing should be according to sections 2.4 to 2.6 of Approved Document J. An internal flue size of 200mm square or round is commonly specified as this size will allow most types of stove or standard open fire to be fitted.
If an inglenook or large open fire is proposed it is necessary to have a larger flue size, which can be calculated according to Approved Document J, section 2.7. Note: Your attention is drawn to 'ADJ Table 2 Size of flues in chimneys' which gives minimum flue sizes for the different appliance and solid fuel types, which must be complied with.
4. During construction of a new house the chimney is usually built "traditionally" in brick or blockwork surrounding clay, refractory concrete, pumice, or ceramic flue liners. It is also possible to use a chimney block or factory made metal chimney system.
5. A new chimney can be added to an existing house quickly and economically using a factory made metal or chimney block system.
6. Rebuilding or relining an existing chimney requires specialist advice. Providing the existing chimney structure is sound, there is a wide choice of factory made chimney relining systems that can be used. Fire-resistant precast concrete, clay and pumice flue liners or ceramic liners offer the most permanent solution, providing the existing chimney openings are big enough to take the correct flue size to suit the proposed appliance.
Cast In-Situ lining systems are also available (see Part 3 Section J) which have been tested by an independent body, such as HETAS or BBA, to meet the appropriate requirements of BS EN 1857:2003 at the T400 N2 D 3 G level using tested materials which are installed under an accepted Code of Practice.
It is desirable for such installations to be independently monitored under a QA inspection system. Double skin flexible stainless steel flue liners offer an alternative answer if access is difficult or the existing chimney is unable to accept other types of liners.
However, these flexible liners, whilst being easier to install and replace, are not permanent and significant periods of slow burning with solid fuels or infrequent chimney sweeping can cause corrosion damage which reduces the expected life to less than 5 years.
Under no circumstances should a single skin flexible liner designed solely for use with gas fires be used with a solid fuel burning appliance.
7. The efficiency and life expectancy of any chimney is dependent on correct use and maintenance. Masonry and precast chimney products whilst usually offering long life and high resistance to risk of corrosion, tend to involve more installation work, when compared with metallic chimney systems.
Metal liners and insulated metal chimneys offer fast and convenient installation. However, they are less resistant to damage by corrosion particularly if subjected to abuse or inadequate cleaning.
Allowing soot or condensate deposits to accumulate in metal lined chimneys and also prolonged periods of burning solid fuel slowly in slumbering conditions, particularly on closed appliances, can cause high concentrations of corrosive condensates to build up and attack the metal liner. This situation can considerably reduce the life of the flue lining.
8. Prefabricated factory made fireplace recess components such as throat forming lintels, gather units or appliance chambers are available with most systems.
9. The manufacturer's installation and user instructions must be followed. Members of the BFCMA are able to provide full details and free advice on their products, including layout design and estimating services.
The British Standard BS EN 15287-1 Design, installation and commissioning of chimneys. Chimneys for non-roomsealed heating appliances ( which has replaced BS 6461 : Part 1 : 1984 (1998), the ‘Code of Practice for masonry chimneys and flue pipes’), and BS EN 12391-1:2003 details the method of specifying the design and installation of metal chimneys (which replaced BS 7566 : 1992 (1998) for ‘installation of factory made chimneys to BS 4543 for domestic appliances’).
NOTE: BS 7566 was withdrawn in December 2005 and replaced with BS EN 12391-1:2003. The provisions for the design, installation and commissioning of metal chimneys, currently in BS EN 12391-1, will be replaced by BS EN 15287-1 when the document National Annex is updated to include these provisions. 3. CHIMNEY MAINTENANCE AND SWEEPING 1. The flueways in the chimney and flue pipe must be cleaned regularly to remove all soot deposits and prevent blockage of the flue. This should be done at least twice a year, preferably before the heating season to check that the flue has not been blocked by bird's nests for example and also at the end of the heating season to prevent soot deposits from resting in the chimney during the dormant period.
2. When using a new installation the flueways should be checked at least monthly, so that an adequate cleaning cycle can be determined in relation to the use of the appliance. The risk of heavy tar and soot deposits is greatly increased if unsuitable fuel is burnt, which can result in a chimney fire or corrosion damage.
3. Sweeping with a brush and rods is the only recommended method of cleaning, because other materials such as mortar in old flues, loose bricks or bird's nests etc. can block a flue. For this reason vacuum or chemical chimney cleaners cannot be recommended as an alternative to sweeping. Some chemical cleaners can corrode metal in the chimney and appliance.
Sweeping brushes must be made from suitable bristle and be of the appropriate diameter for the area of the flue being swept. They must also be fitted with a ball end or free running wheelboss to prevent scraping or damaging the flue lining particularly at bends.
4. HETAS recommends the use of a qualified chimney sweep who will usually be a member of the National Association of Chimney Sweeps, Guild of Master Chimney Sweeps or the Association of Professional Independent Chimney Sweeps who can give an inspection and sweeping certificate.
HETAS Approved Sweeps are listed in Section E. Many chimney manufacturers give specific advice on what sweeping brushes to use with their products. This advice should be followed.
5. As recommended by British Standards all chimneys should be checked annually for signs of wear and tear such as flashings, supports, terminals and any other exposed areas of the chimney, so that repairs can be carried out as necessary.
6. If at any time smoke or fumes are apparent or suspected to be escaping from the appliance or chimney, stop using the appliance at once and get advice immediately from the installer and or fuel supplier. Do not use the appliance or burn any fuel until the installation has been checked and passed as being safe.