INSTRUCTIONS FOR THE INSTALLER 8
2.
cowl or a smoke extraction fan, or reshape
the chimney.
Never make 90º bends, due to the great
loss of draught they cause, and reduce 45º
bends down to an absolute minimum. Each
45º bend is equivalent to a 0.5m reduction
in flue length. Horizontal flue sections
should not be installed because they cut
updraught a great deal.
If the flue draws at more than 20 Pa,
then an effective damper must be fitted on
the flueway. This damper must be visible
and accessible.
The chimney flue must not rest on the
appliance.
Bear in mind that high temperatures
may be reached in the flue, meaning that it
is essential that insulation be enhanced in
sections in which combustible material is
present (wooden beams, furniture, etc.). It
may even be necessary to protect non-
combustible material in order to prevent
breakage, deformation, etc., as a result of
overheating if the material is not designed
to withstand high temperatures.
It must be possible to clean the entire
flue, no sections being left inaccessible for
cleaning purposes.
2.4.2. Chimney crown
The upper end of the chimney must
clear the roof, the roof ridge or any
obstacle located on the roof by at least 1m.
Figure No.5 - Distances between chimney
crown and roof ridge
The chimney crown must clear the
highest point of any neighbouring building
or obstacle located within a 10m radius of
the chimney outlet by more than 1m.
