Version of 27 Oct 2011
Page 2 of 7
BOILER PERFORMANCE
The nominal heat outputs for the various boilers are detailed in the main instruction manual:
PREPARATORY WORK AND SAFETY CHECKS
IMPORTANT WARNING
This boiler must not be installed into a chimney that serves any other heating appliance.
There must not be an extractor fan fitted in the same room as the boiler as this can cause the boiler to emit
fumes into the room.
Chimney
In order for the boiler to perform satisfactorily the chimney height must be sufficient to ensure an adequate
draught of approximately 15 Pa 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 boiler to the top
of the chimney should be satisfactory. Alternatively the calculation procedure given in BS EN 13384-1 may be
used as the basis for deciding whether a particular chimney design will provide sufficient draught.
The outlet from the chimney should be above the roof of the building in accordance with the provisions of
Building Regulations Approved Document J.
Because these boilers run at high efficiencies the temperature of the flue gases is lower than conventional
solid fuel appliances. Although they are not classed as condensing appliances, the low flue gas temperature
results in condensation occurring within the flue. Any chimney flue system must therefore be able to withstand
the effects of condensate and operate under wet conditions (designation letter W). In addition it should be
soot fire resistant and able to withstand the corrosive effects of flue products generated by solid fuels
(designation G and 3 respectively). If installation is into an existing masonry chimney then it will require re-
lining with a liner meeting the specification described above. Existing concrete or clay lined chimneys are not
suitable for these boilers and must be lined as described above. All installations must be 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 lining system.
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 boiler to the chimney but is not suitable for use as
the complete chimney. The chimney and connecting fluepipe must not be less than the size of the outlet
socket of the boiler. The length of this connecting pipe should be kept to a minimum. Refer also to the main
instruction manual for further guidance.
Any bend in the chimney or connecting fluepipe should not exceed 45 . 90 bends should not be used,
except for connecting to a rear outlet appliance, and the connection should be no more than 150 mm in length
and have a debris trap.
Combustible material should not be located where the heat dissipating through the walls of fireplaces or flues
could ignite it. Therefore when installing the boiler 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 boiler instructions.
If it is found that there is excessive draught in the chimney then a draught stabiliser should be fitted in the
chimney above the chimney above the flue pipe connection. Fitting of a draught stabiliser will affect the
requirement for the permanent air supply into the room in which the boiler is fitted in accordance with
