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Purpose and scope of Technical Booklet L
0.1NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
This Technical Booklet gives guidance on how to satisfy the requirements of Part L. Although Part L applies to the accommodation of any combustion installation and liquid fuel storage system within th
dwellingcombustion-appliancesfuel-storagePerformance requirements for combustion appliances
0.2NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
It is the view of the Department that the requirements of regulations 70, 71, 72, 73 and 74 in Part L will be met if the building provides for the safe accommodation of combustion appliances which – (
combustion-appliancesfire-safetyventilationSection 2 provisions overview
0.3NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The guidance in Section 2 sets out the general provisions for combustion appliances that should be met, specifically air supply, flues, access for maintenance, notice plates for hearths and flues, and
combustion-appliancesventilationfire-safetyFactory-made metal chimneys
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Factory-made metal chimneys (also known as system chimney) – prefabricated chimneys that are commonly manufactured as sets of components for assembly on site (although they can be supplied as one unit
combustion-appliancesFanned draught installation
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Fanned draught installation – the proper discharge of the flue gases depends upon the operation of a fan, which may be separately installed in the flue or may be an integral part of the combustion app
combustion-appliancesFlue block chimney systems definition
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Flue block chimney systems – a set of factory-made components made from precast concrete, clay or other masonry units that are designed for assembly on site to provide a complete chimney having the pe
fluescombustion-appliancesFlue box definition
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Flue box – a factory-made unit, usually made of metal, which is similar to a prefabricated appliance chamber except that it is designed to accommodate a gas-burning appliance in conjunction with a fac
fluescombustion-appliancesgasNatural draught flue
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Natural draught flue – the combustion products flow into the flue as a result of the buoyancy force produced due to the difference between the temperature of the gases within the flue and the temperat
combustion-appliancesflue-systemsOpen-flued appliance definition
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Open-flued appliance – one which draws its combustion air from the room or space within which it is installed and which requires a flue to discharge its products of combustion to the outside air. See
combustion-appliancesflue-systemsPrefabricated appliance chamber definition
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Prefabricated appliance chamber – a set of factory-made pre-cast concrete components designed to provide a fireplace recess to accommodate an appliance such as a stove, and incorporates a gather when
combustion-appliancesfire-safetyInteraction of mechanical extract ventilation and open-flued combustion appliances - general principle
2.16-2.17NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Extract fans lower the pressure in a building and this can cause the spillage of combustion products from an open-flued appliance. In a building where it is intended to install an open-flued applianc
combustion-appliancesventilationsafetyProvision of flues
2.18, 2.19NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
This Technical Booklet provides guidance on how to construct a flue or chimney that serves only one appliance. A flue designed to serve more than one appliance should follow the recommendations of BS
combustion-appliancesflues-and-chimneysCondensates in flues
2.20NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue should provide satisfactory control of water condensation. This can be achieved by adopting one of the following provisions – (a) the flue for a non-condensing combustion appliance should be in
combustion-appliancesflues-and-chimneysdrainageConstruction of masonry chimneys
2.21NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A new chimney should be constructed with a flue liner and masonry suitable for the intended application. The following liners are suitable for a solid fuel appliance as well as being generally suitabl
combustion-appliancesflues-and-chimneysInstallation of flue liners
2.22NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A liner should be installed in accordance with the manufacturer's instructions. Appropriate components should be selected to form the flue without cutting and to keep joints to a minimum. Bends and of
combustion-appliancesflues-and-chimneysFilling spaces between chimney liner and masonry
2.22NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Spaces between the lining and the surrounding masonry should not be filled with ordinary mortar. In the absence of the liner manufacturer's instructions, the space should be filled with one of the fol
combustion-appliancesflue-systemschimneyConstruction of flue block chimneys
2.23NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue block chimney should be constructed of factory-made components suitable for the intended application and installed in accordance with the manufacturer's instructions. The flue blocks should hav
combustion-appliancesflue-systemschimneySealing joints and forming bends in flue block chimneys
2.24NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Joints should be sealed in accordance with the flue block manufacturer's instructions. Bends and offsets should only be formed with matching factory-made components.
combustion-appliancesflue-systemschimneyWall thickness for masonry and flue block chimneys
2.25NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The thickness of the walls for a masonry chimney around the flue, excluding the thickness of any flue liner, should be in accordance with Diagram 2.4.
combustion-appliancesflue-systemschimneystructuralFlue pipe materials
2.26NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue pipe should be constructed from – (a) cast iron complying with BS 41; (b) metal flue pipes appropriately designated in accordance with BS EN 1856: 2 to suit the appliance and types of fuels to
combustion-appliancesflue-systemsFlue pipe joint installation
2.27NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue pipe with spigot and socket joints should be fitted with the socket facing upwards to contain moisture and other condensates in the flue. Joints should be made gas-tight by the use of proprieta
combustion-appliancesflue-systemsPlastic flue pipe designation
2.28NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A plastic flue pipe should be appropriately designated in accordance with BS EN 14471 to suit the appliance, fuel and flue characteristics.
combustion-appliancesflue-systemsExisting flue re-use and repair
2.29NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where it is proposed to bring an existing flue back into use, or an existing flue is to be used with a different type or rating of combustion appliance, it should be cleaned, visually inspected and if
combustion-appliancesflue-systemsDefective flue lining
2.30NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A defective flue should be lined using the materials and components described in Sections 3, 4, and 5 dependent upon the type of combustion appliance proposed.
combustion-appliancesflue-systemsFlue area sizing for lining
2.31NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The use of an oversized flue can be unsafe so a flue should be lined to reduce the flue area to suit the intended combustion appliance.
combustion-appliancesflue-systemsMetal liner replacement on appliance replacement
2.32NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
If a chimney has been relined in the past using a metal lining system and the appliance is being replaced, the metal liner should also be replaced, unless it can be proven that it was recently install
combustion-appliancesflue-systemsFlexible metal flue liners for chimney relining
2.33NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A chimney may be relined using a flexible metal flue liner, appropriately designated in accordance with BS EN 1856: 2 to suit the appliance, fuel and flue gas characteristics. Flexible flue liners sho
combustion-appliancesflue-systemsFactory-made metal chimneys - certification and installation
2.34NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A factory-made metal chimney should be – (a) a component system independently certified as complying with the relevant sections of BS EN 1856: 1 and installed in accordance with the relevant recommend
non-domesticdwellingcombustion-appliancesFactory-made metal chimney wall penetration and access
2.35NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where a factory-made metal chimney passes through a wall, sleeves should be provided to prevent damage to the flue or building through thermal expansion. To facilitate the checking of gas-tightness, j
non-domesticdwellingcombustion-appliancesFactory-made metal chimney removal without dismantling
2.36NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A factory-made metal chimney should be installed so that the appliance can be withdrawn without the need to dismantle the chimney.
non-domesticdwellingcombustion-appliancesFactory-made metal chimney distance from combustible materials
2.37NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A factory-made metal chimney should be kept a safe distance away from any combustible material. For a chimney designated to BS EN 1856: 1 the following provisions are a reasonable method of achieving
non-domesticdwellingcombustion-appliancesfire-safetySeparation of Combustible Material from Factory-Made Metal Chimney
Diagram 2.5NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
No combustible material in shaded zone. Width of shaded zone at least equal to manufacturer's declared minimum distance (XX mm) as defined by testing to BS EN 1443: 2003 or 25 mm, whichever is the gre
fire-safetycombustion-applianceschimneyAccess provisions for concealed flues
2.39NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where a flue is routed within a void, appropriate means of access at strategic locations should be provided to allow the following aspects to be visually checked and confirmed – (a) the flue is contin
combustion-appliancesSizing and positioning of flue access points
2.39NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The means of access for flues needs to be sufficiently sized and positioned to allow a visual inspection of the flue to be undertaken, particularly at any joints in the flue. It is not intended that t
combustion-appliancesFlue routing restrictions
2.39NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Flues should not pass through another premises since access for inspection may not always be available to that premises and chimney system running through it. Flues may pass through communal areas inc
combustion-appliancesflatsFire, thermal and acoustic isolation of access hatches
2.39NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Any 'means of access' should not impair any fire, thermal or acoustic requirements of the Building Regulations. Where necessary, inspection panels or hatches should be fitted with resilient seals and
fire-safetycombustion-appliancesMinimum dimensions for access hatches
2.39NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Access hatches should be at least 300 mm x 300 mm or larger where necessary to allow sufficient access to the void to look along the length of the flue.
combustion-appliancesInspection hatch requirements for concealed flues
Diagram 2.6NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
all voids containing concealed flues should have at least one inspection hatch measuring not less than 300 mm x 300 mm no flue joint within the void should be more than 1500 mm distant from the edge
combustion-appliancesflue-inspectionaccessibilityConfiguration of natural draught flues serving open-flued appliances
2.40NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue system should offer least resistance to the passage of the flue gas by minimising changes in direction or horizontal length. Where practicable the flue should be straight and vertical except fo
combustion-appliancesfluesopen-fluedLimits on flue bends and changes of direction
2.41NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Provisions should be made to enable the flue to be swept and inspected. The number of changes of direction between the combustion appliance outlet and the flue outlet should be limited to not more tha
combustion-appliancesfluesopen-fluedmaintenanceOpenings in flues for inspection and cleaning
2.42NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue should not have an opening into more than one room or space except for the purposes of – (a) inspection or cleaning; or (b) fitting an explosion door, draught break, draught stabiliser or draug
combustion-appliancesfluesopen-fluedOpenings for inspection and cleaning
2.43NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Openings for inspection and cleaning should be formed using purpose factory-made components that are compatible with the flue system. The access cover to the opening should have the same level of gas-
combustion-appliancesflue-systemsFlue cleaning requirements
2.44NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Openings for cleaning the flue should allow easy passage of the sweeping brush and be non-combustible except where fitted to a combustible flue pipe, such as a plastic flue pipe. It should be possible
combustion-appliancesflue-systemsmaintenanceDry lining around fireplace openings
2.45NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where a decorative treatment, such as a fireplace surround, masonry cladding or dry lining, is provided around a fireplace opening, any gaps that could allow flue gas to escape from the fireplace open
combustion-appliancesfireplacegas-safetyFlue completion checks
2.46NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue should be checked at completion to ensure that it is free from obstructions, satisfactorily gas-tight and constructed with materials and components of sizes that suit the intended application.
combustion-appliancesflue-systemstestingfire-safetyNotice plates for hearths and flues
2.47NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
To satisfy the requirements of Regulation 74 in Part L, a durable notice should be provided to convey – (a) the location of the hearth, fireplace (or flue box) or the location of the beginning of the
combustion-appliancesflue-systemsinformation-provisionPositioning of notice plates
2.48NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Notice plates should be robust, indelibly marked and securely fixed in an unobtrusive but obvious position within the building such as – (a) next to the electricity consumer unit; or (b) next to the c
combustion-appliancesflue-systemsinformation-provisionEuropean Standard flue product designations on notice plates
2.49NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
For flue products whose performance characteristics have been assessed in accordance with a European Standard (EN) and which are supplied or marked with a designation as defined in Section 2, the inst
combustion-appliancesflue-systemsAccess to combustion appliances for maintenance
2.50NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A permanent means of safe access should be provided to a combustion appliance for maintenance.
combustion-appliancesmaintenanceFlue sizing based on appliance type
3.5NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A flue should be not less than the size shown in Table 3.2 that is relevant to the particular appliance, and not less than the size of the appliance flue outlet or that recommended by the appliance ma
non-domesticdwellingcombustion-appliances