Bosch Worcester Greenstyle Bewdley 8 Installation, Servicing And User Instructions Manual page 18

CHIMNEY
In order for the stove to perform satisfactorily the chimney height must
be sufficient to ensure an adequate draught of approximately 15 Pa
when hot so as to clear the products of combustion and prevent smoke
problems into the room.
NOTE: A chimney height of not less than 4.5 metres measured
vertically from the outlet of the stove to the top of the chimney should
be satisfactory. Alternatively the calculation procedure given in EN
13384-1 may be used as the basis for deciding whether a particular
chimney design will provide sufficient draught. BS EN 15287-1:2007
gives additional details.
The outlet from the chimney should be above the roof of the building
in accordance with the provisions of Building Regulations Approved
Document J.
If installation is into an existing chimney then it must be sound and have
no cracks or other faults which might allow fumes into the house. Older
properties, especially, may have chimney faults or the cross section may
be too large i.e. more than 230 mm x 230 mm. Should remedial action
be required, expert advice should be sought. If it is found necessary to
line the chimney then a flue liner suitable for solid fuel must be used in
accordance with Building Regulations Approved Document J.
Any existing chimney must be clear of obstruction and have been swept
clean immediately before installation of the stove. If the stove is fitted in
place of an open fire then the chimney should be swept one month after
installation to clear any soot falls which may have occurred due to the
difference in combustion between the stove and the open fire.
If there is no existing chimney then any new system must be to
the designation described above and in accordance with Building
Regulations Approved Document J.
A single wall metal fluepipe is suitable for connecting the stove to
the chimney but is not suitable for use as the complete chimney. The
chimney and connecting fluepipe must have a minimum diameter of
125mm for Bewdley 3 & 5, 150mm for Bewdley 8, and its dimension
should be not less than the size of the outlet socket of the stove.
Any bend in the chimney or connecting fluepipe should not exceed 45°,
90° bends should not be used.
Combustible material should not be located where the heat dissipating
through the walls of fireplaces or flues could ignite it. Therefore when
installing the stove in the presence of combustible materials due
account must be taken of the guidance on the separation of combustible
material given in Building Regulations Approved Document J and also
in these stove instructions. If it is found that there is excessive draught
in the chimney then a draught stabilizer should be fitted. Fitting of a
draught stabiliser will affect the requirement for the permanent air
supply into the room in which the stove is fitted in accordance with
18
Approved Document J (see also combustion air supply).
Adequate provision e.g. easily accessible soot door or doors must be
provided for sweeping the chimney and connecting fluepipe where it is
not intended for the chimney to be swept through the appliance.
This stove may be connected with a factory built or masonry chimney
with a minimum diameter of 125mm Bewdley 3 & 5, and 150mm
Bewdley 8. If you are using a factory built chimney, it must comply with
BS EN 1856-1:2003 standard. It is very important that it is installed
according to the manufacturer's specifications.
If you are using a masonry chimney, it is important that it be built in
compliance with the specifications contained in Document J.
The interior diameter of the chimney flue must be no smaller than the
diameter of the stove smoke exhaust pipe. A flue which is too small
may cause draught problems, while a large flue promotes rapid cooling
of the gas, and hence the build-up of creosote and the risk of chimney
fires. Note that it is the chimney and not the stove which creates the
draught effect; the stove's performance is directly dependent on an
adequate draught from the chimney.
The following points are important for the installation of the chimney:
• It must rise above the roof at least 0.9m from the uppermost point
of contact.
• The chimney must exceed any part of the building or other
obstruction within a 3.04m distance by a height of 0.6m.
Installation of an interior chimney is always preferable to an exterior
chimney. Indeed, the interior chimney will, by definition, be hotter than
an exterior chimney, being heated up by the ambient air in the house.
Therefore the gas which circulates will cool more slowly, thus reducing
the build-up of creosote and the risk of chimney fires. The draught
caused by the tendency for hot air to rise will be increased with an
interior chimney.
Using a chimney cap at the extremity of the chimney requires regular
inspection in order to ensure that it is not obstructed thus blocking
the draught, and it should be cleaned when used regularly. Exterior
chimney should be double or triple wall.
CONNECTION TO CHIMNEY
Stoves may have a choice of either a rear or top flue gas connector
that allows connection to either a masonry chimney or a prefabricated
factory-made insulated metal chimney in accordance with their
instructions.
REGULAR CLEANING
It is important that the appliance, flue gas connector and chimney are
regularly cleaned and checked for any possible blockages prior to re-
lighting after a prolonged shut down.
INSTALLATION
6720818040 B 04/2017