Graphite GR910-B, Instruction Manual

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ing and any other obstructions, such as trees, which
are within 3m (10’) of the flue terminal. Failure to do
this could cause an unwelcome down-draughts which
would mean, under certain conditions, potentially
dangerous flue gases being emitted into the room.
If you are using an existing chimney and it has been
checked for condition and suitability (see below), in
the interests of safety you must ensure that it is swept
before the stove is installed, even if it has never been
used or you intend to use a flexible liner. To find a
local registered sweep visit The National Association of
Chimney Sweeps at
www.chimneyworks.co.uk or the
Guild of Master Chimney Sweeps at
www.guildofmasterchimneysweeps.co.uk .
The recommended minimum height for the chimney /
flue system from the top of the stove to the top of the
chimney terminal is 4.5m (15’). If this is not possible
then a ‘spinner’ type cowl, to compensate for any
potential limited up-draught, specialist advice should
then be sought on the correct type of cowl to use.
Under no circumstances should the stove’s 150mm
(6”) diameter flue be reduced in any part of the flue
system as this could cause a build-up of dangerous
carbon monoxide (CO) gas.
Since stoves create flue gases at a much greater
temperature than those produced by an open fire or
gas appliance it does not necessarily follow that your
chimney will function adequately (or safely) when
your new stove is installed. The best way to ensure
that you have a fully functioning flue system is to fit
an approved flexible solid fuel flue liner. If you intend
to predominantly burn mineral fuels or slumber burn
then 904L grade liner will provide greater resistance
to any acidic condensates produced by burning
mineral fuels.
When your new boiler stove is installed with a flexible
flue liner it should be possible to sweep the chimney
through the stove by simply removing the baffle plate
inside the stove and the fire chamber access plate on
top of the stove (see pages 11 and 12). However, if
you do not use a liner the installer should, if possible,
provide an alternative means, such as a soot door with
an adequate air-tight seal, in the chimney wall to be
able to clean the whole of the chimney / flue system.
Flexible Stainless Steel Chimney Liners
Graphite strongly recommend fitting a chimney liner
for the following reasons:
• A flue liner is a major ‘quantifiable’ component in a
total and fully functioning flue system. It will provide
a consistent flue draught from the stove through to
the chimney terminal and when back-filled with
vermiculite will deliver much needed insulation to
keep flue gases as hot as possible (particularly
important for boiler stoves) which will help minimise
the amount of smoke and soot produced. It will also
improve the stove’s operation with greater control
over the fuel burn rate and efficiency.
• Your existing chimney could leak smoke, fumes and
potentially dangerous ‘invisible’ carbon monoxide into
other parts of the building.
• Condensation or creosote ‘tar’, often associated
with burning wood, could eventually seep through the
walls, particularly if they are made of old or porous
brick and / or are jointed with lime mortar, eventually
causing unsightly stains on decorative coverings.
• Stoves work best with the correct draught. Pre-1965
chimneys which have been built for open fires have
larger (and irregular shaped) voids than those best
suited for a modern stove and thus could reduce the
effectiveness of the flue draught by making the flue
too cold and difficult to warm. This is a particular
problem if the chimney breast is on an outside wall
and is subject to a strong prevailing wind.
• The interior surfaces of older flues could be eroded
and also have rough surfaces which could cause
resistance to the smooth flow of gases and
consequently result in poor up-draught.
• Unfortunately many houses built since 1965 with
clay or concrete chimney liners suffer from these
being poorly installed, either through being fitted the
wrong way up or not receiving an appropriate
application of mortar to make a complete seal on
each joint. Even though not particularly old, this could
still potentially cause leaking smoke and fumes or
condensation stains
Your approved installer will be able to advise you on
the suitability of your chimney after undertaking a
thorough inspection and smoke test. Any solid fuel
flexible liner which is specified should be double
skinned stainless steel, either 904L or 316Ti grade and
be CE marked and / or Hetas Approved. We strongly
recommend the thicker 904L grade for the Graphite
Boiler, especially if you propose to burn mineral fuels
as this will be more resistant to their associated acidic
condensates.
The British Flue and Chimney Manufacturers
Association website
www.bfcma.co.uk, produces a
number of authoritative and informative download
guides to flues and chimneys for stoves.
Important: If you are not using a chimney liner
you must provide a means of inspecting and
cleaning the flue and chimney.
The Chimney Terminal
The existing chimney pot or terminal must be suitable
for stove installation and should not restrict the smoke
and fumes from the stove. It must provide at least the
same outlet area as the flue pipe. It may be that your
existing chimney terminal has been replaced with a
ventilating terminal if the fireplace has been closed off
at some point and this will need replacing.
Your installer will be able to advise you on the correct
specification of any new cowl or terminal. Cowls have
the additional advantage of limiting rain entering the
flue system which could cause the inside of the stove
to rust when it is not being used, particularly during
the long periods outside the heating season.