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CI-2013-05-14
3.1Size of flue in chimneys
Size of Flue in Chimneys
Installation
1
Minimum flue size
Fireplace with an opening of up to 500mmX500mm
200mm diameter or rectangular/square flues having the same
cross-sectional area and a minimum dimension not less than
175mm.
Fireplace with an opening in excess of 500mmX500mm or a
fireplace exposed on two or more sides.
See paragraph 2.7 of the ADJ. If rectangular/square flues are used
the minimum dimension should not be less than 200mm.
Closed appliance of up to 20kW rated output which:
a)
Burns smokeless or low-volatiles fuel
2
or
b)
Is an appliance which meets the requirements of the
Clean Air Act when burning an appropriate bituminous
coal
3
or
c)
Is an appliance which meets the requirements of the
Clean Air Act when burning wood
3
.
125mm diameter or rectangular/square flues having the same
cross-sectional area and a minimum dimension not less than
100mm for straight flues or 125mm foe flues with bends or offsets.
Pellet burner or pellet boiler which meets the requirements of the
Clean Air ACT
3
.
125mm diameter
This may be reduced to no less than 100mm when permitted by the
appliance manufacturer and supported by calculation according to
BS EN 13384-1:2002. This calculation can be applied to an
individual installation or manufacturers can provide pre-calculated
designs.
Other closed appliance of up to 30kW rated output burning any
fuel.
150mm diameter or rectangular/square flues having the same
cross-sectional area and a minimum dimension not less than
125mm.
Closed appliance of above 30kW and up to 50kW rated output
burning any fuel.
175mm diameter or rectangular/square flues having the same
cross-sectional area and a minimum dimension not less than
150mm.
NOTES:
1.
Closed appliances include cookers, stoves, room heaters and boilers
2.
Fuels such as bituminous coal, untreated wood or compressed paper are not smokeless or low-volatiles fuels.
3.
These appliances are known as „exempted fireplaces‟.
An overly large chimney aperture will mean that too much energy will be required to heat the chimney sufficiently
to achieve an acceptable draught. If you have a brick chimney with a large aperture, we recommend that you
install an insulating chimney liner of the proper diameter.
This will increase the draught, and improve the fuel economy.
The height and positioning of the chimney must comply with the guidance given in Approved Document J of The
Building Regulations, particularly Sections 2.6
– 2.21.
The chimney must be accessible for external inspection, and it must be possible to access the cleaning doors
and the chimney if it is to be cleaned from the top (e.g. steel chimneys).
Be aware of the following:
If there is insufficient draught in the chimney, it may be a good idea to install the flue pipe straight up so as to
minimise smoke migration in the actual combustion chamber.
Avoid having more bends than necessary, and limit the length of the flue pipe so as not to reduce the draught.
3.2 Fresh air supply
A wood-burning stove requires air for combustion. As a result, firing a wood-burning stove will help create a
healthy climate in your house. The ventilation requirements are described in Sections 2.1
– 2.3 and Table 1 of
the Approved Document J.
If it is necessary to install air grilles, they must be positioned so that they cannot be obstructed.
