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Performance 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-safetyEquivalent area definition
NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Equivalent area – the area of a sharp-edged circular orifice which would pass the same air flow rate at the same applied pressure difference as the product or device being tested. The equivalent area
ventilationAir supply for combustion appliances
2.1, 2.2NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
All combustion appliances require the supply of air for combustion and to ensure the proper operation of the flue. A flueless appliance also needs air to ensure that the products of combustion are saf
ventilationnon-domesticdwellingVentilation of appliance compartments
2.3, 2.4, 2.5NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
An appliance compartment that encloses an open-flued appliance should be provided with an air vent(s) large enough to admit all of the air required for combustion and the proper operation of the flue.
ventilationnon-domesticdwellingVentilation via other rooms or spaces
2.6, 2.7NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
If a combustion appliance is room-sealed but takes its combustion air from another space in the building, or if a flue has a permanent opening to another space in the building, that space should have
ventilationnon-domesticdwellingProprietary ventilation assemblies
2.8NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where ventilation is to be provided via a single proprietary assembly the equivalent free area of the air vent should be taken to be the manufacturer's value. The manufacturer may call this a free are
ventilationnon-domesticdwellingNon-proprietary ventilation assembly requirements
2.9NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where two or more components are to be used to provide a non-proprietary ventilation assembly, the assembly should be kept as simple and smooth as possible. The assembly should be taken to have an equ
ventilationDetermining equivalent area of ventilators
2.10NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The equivalent area stated in the ventilator manufacturer's literature or marked on the air vent should be used whenever it is available, as this can differ considerably from the free area measured at
ventilationGrille and mesh aperture dimensions
2.11NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Grilles or meshes protecting air vents from the entry of animals or birds should have individual aperture dimensions of not less than 5 mm.
ventilationPermanently open ventilation of rooms
2.12NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A room containing an open-flued appliance must receive a continuous supply of air from outside. The volume of air required depends on the type and rating of the appliance. This normally means the inst
non-domesticventilationPositioning and installation of permanently open air vents
2.13NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A permanently open air vent should be non-adjustable and be positioned where it is unlikely to become blocked. It should be so installed that the building occupants are not provoked into sealing it ag
ventilationfire-safetySizing of permanently open air vents
2.14NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A permanently open air vent should be sized so that the free area, or the equivalent free area of a more complex design, is sufficient for the appliance to be installed, taking account where necessary
ventilationMinimising discomfort from cold draughts and noise
2.15NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Any discomfort from cold draughts can be avoided by placing the air vent close to the appliance, drawing air from other parts of the building or by ensuring a good mix of the incoming cold air by plac
ventilationsoundInteraction 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-appliancesventilationsafetyExtract fan rate limits for gas appliances with open-flued combustion
2.17(a)NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
for a gas appliance – where a room contains an open-flued appliance, the room extract fan rate should not exceed 20 litres/second (72 m3/hour), and a spillage test as recommended in BS 5440: 1 should
gas-applianceopen-fluedventilationfire-safetyExtract fan rate limits for oil appliances with open-flued combustion
2.17(b)NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
for oil appliances – where a room contains an open-flued appliance the extract rate should be limited to 40 litres/second for an appliance with a pressure jet burner and 20 litres/second for an applia
oil-applianceopen-fluedventilationfire-safetyExtract fan installation for solid fuel appliances with open-flued combustion
2.17(c)NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
for a solid fuel appliance – a room extract fan should not be installed in the same room. If mechanical extraction is unavoidable then seek specialist advice from a mechanical/services engineer to ens
solid-fuel-applianceopen-fluedventilationfire-safetySpecialist advice for commercial and industrial installations with combustion appliances
2.17(d)NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
for commercial and industrial installations – specialist advice from a mechanical/services engineer may be necessary with regard to the possible need for the interlocking of gas heaters and any mechan
commercialindustrialgas-applianceventilationPermanent vent openings in a solid floor for open-flued appliances
Diagram 2.3NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Diagram 2.3 Permanent vent openings in a solid floor airbrick, duct and grille should have an equivalent free area at least that recommended in Sections 3, 4 or 5 as relevant
open-fluedventilationdrainageAir supply to appliances
3.1NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Any room or space containing a combustion appliance should have a permanent air vent opening of a size not less than that shown in Table 3.1. For an appliance designed to burn a range of different sol
non-domesticcommercialfire-safetyventilationManufacturer's installation instructions for air vents
3.2NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where the manufacturer's installation instructions require greater areas of permanently open air vents than those specified in Table 3.1, the manufacturer's advice should be followed.
non-domesticcommercialfire-safetyventilationAir supply to solid fuel burning appliances
Table 3.1NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Table 3.1 Air supply to solid fuel burning appliances Type of appliance: Open appliance such as an open fire with no throat, e.g. a fire under a canopy as in Diagram 3.6 | Type and amount of ventilat
dwellingflatsventilationAir supply notes and exceptions
Table 3.1 NotesNI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Notes: (1) Extract fans should not be installed in the same room or space as a solid fuel burning appliance, see paragraph 2.17. (2) For simple open fires as depicted in Diagram 3.12 the air supply re
dwellingflatsventilationAir supply for flued Decorative Fuel Effect (DFE) fires - no vent needed
4.5NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A permanently open air vent should not be necessary for a DFE fire provided – (a) the dwelling in which it is to be installed has an air permeability greater than 5.0 m3/hr/m2. See Appendix C; (b) the
dwellingventilationAir supply for flued DFE fires - vent sizing requirements
4.6NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Where the provisions of paragraph 4.5 do not apply, any room or space intended to contain any other DFE fire should have a permanently open air vent as follows – (a) for a DFE fire in a fireplace rece
dwellingventilationAir supply for other flued appliances
4.7, 4.8NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
This type of combustion appliance includes Inset Live Fuel Effect (ILFE) fires, radiant convector fires and boilers, in both room-sealed and open-flued variants. The size of the free air supply to th
dwellingnon-domesticventilationExample calculation of free area of air vent for open-flued boiler
4.9NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
An open-flued boiler with a rated input of 15 kW (net) is installed in an appliance compartment such as a boiler room, which is ventilated directly to the outside. The design of the boiler is such tha
dwellingnon-domesticventilationFree areas of permanently open air vents for gas appliance installations
Diagram 4.2NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Appliance in a room or space or appliance compartment ventilated via an adjoining room or space or appliance compartment ventilated direct to outside: Open-Flued: A = 500 mm² per kW input (net) B = 1
dwellingnon-domesticventilationVentilation for flueless gas appliances
4.10NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The ventilation for a flueless gas appliance should be provided in accordance with Table 4.1. For some flueless appliances, it may be necessary to provide permanently open air vents and/or make provis
non-domesticdwellingventilationGas point sizing for flueless appliances
4.11NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A room containing a gas point intended for use with a flueless appliance (such as a cooker, or space heater or water heater, with the gas point not adjacent to a flue) should have the ventilation prov
non-domesticdwellingventilationVentilation requirements for flueless gas appliances
Table 4.1NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Table 4.1 Ventilation for flueless gas appliances Flueless appliance type | Maximum appliance rated heat input | Volume of room, space or internal space (m³) | Free area of permanently open air vent
non-domesticdwellingventilationExample calculations for flueless space heater ventilation
ExamplesNI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
Examples: a. Space heater in a lounge measuring 4 m x 4 m x 2.4 m = 38.4 m³, the appliance rated input should be not greater than 38.4 x 0.045 = 1.73 kW. b. Space heater in a hallway with a rated inpu
non-domesticdwellingventilationAir supply to appliances
5.3NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
The permanently open air vent for an oil burning appliance should have the free area as given in Diagram 5.1. However, if the manufacturer's installation instructions require a greater area of permane
non-domesticcommercialindustrialventilationExample of calculation of free area of air vent using Diagram 5.1
5.4NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
An open-flued appliance is installed in an appliance compartment such as a cupboard, which is ventilated via an adjoining room. The appliance has a rated output of 11 kW. Air for combustion and the sa
non-domesticcommercialindustrialventilationFree areas of permanently open air vents for oil-fired appliance installations
Diagram 5.1NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
A = 550 mm2 per kW output (see Note 3 and 5) D = 550 mm2 per kW output E = 1100 mm2 per kW output A = 550 mm2 per kW output (see Note 3 and 5) B = 1100 mm2 per kW output C = 1650 mm2 per kW output H =
non-domesticdwellingventilationMinimum ventilation requirements based on dwelling air-tightness
C.1, C.2NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
C.1 The minimum requirements for permanent ventilation for certain appliances depends on a knowledge of the air-tightness of the dwelling where they are to be installed. Dwellings built after 2008 are
dwellingventilationAssessment approach for air permeability of older dwellings
C.3NI-wide·Technical Booklet L Combustion Appliances and Fuel Storage Systems
C.3 Failure to implement even a few of these measures will typically mean that the overall air permeability will probably exceed 5.0 m³/(h.m²) at 50 Pa. However, individual rooms in some older houses
dwellingventilation