Booklet 722
4 Flue And Chimneys
4.1 Requirements
The stove must be connected to a suitable and efficient flue so that products of
combustion (fumes) from the stove are expelled to the outside air. Please remember that
chimney draught is dependent on four main factors :
• Flue gas temperature
• Flue height
• Flue size
• Flue terminal
To ensure a good up draught it is important that the flue gases are kept warm and that
the flue size suits the stove. The termination of the outlet at the top of the flue also
needs to comply with Building Regulations. The minimum effective height of the flue
must be at least 4.5 metres from the top of the stove to the top of the flue outlet. When
warm the flue draught should be between 0.1 to 0.2mb.
The draw of a chimney / flue can vary in different weather conditions and the customer
should be made aware of this. Failure to correct an over-drawing flue will invalidate the
warranty.
A chimney may comply with regulations but could still be subject to down draught and
similar problems. A chimney terminating above the ridge level is generally less likely to
suffer such problems.
If a new chimney is being provided it should fully comply with the relevant Building
Regulations that specify the requirements for solid fuel burning installations. Suitable
types of chimney include the following :
• Masonry Chimney : Built with clay or concrete liners, or a chimney
block system meeting Building Regulations. These types of chimneys
should be installed in accordance with the Building Regulations and BS EN
15287-1:2007.
• Factory Made Insulated Chimney : Complying with BS 4543:Part 2 (often
called Class 1 prefabricated metal chimney). These types of chimneys should
be installed in accordance with Building Regulations and BS EN 15287-1:2007.
Due to the gradual introduction of European Chimney Standards chimneys will be
specified according to their performance designation as defined in BS EN 1443 that
covers the General Requirements for chimneys. The minimum performance designation
required for use with solid fuel burning stoves is T450 N2 S D3.
The flue and chimney installation must be carefully checked by a competent person
before fitting the stove to ensure it is suitable and will work safely.
If the chimney is old (i.e.: built of brick or stone without a liner) or being opened up for
reuse additional checks and smoke testing as described in Appendix E of the Approved
Document J 2010 Edition should also be carried out to ensure the flue and chimney are in
good operating condition.
Page 7
WOODFORD Stove
Installation Guide