
13
INSTALLATION: GENERAL GUIDELINES
Please refer specifically to current building regulations
which apply to your country or region Adopt
whichever provides the highest / safest margin.
The Hearth
The hearth should be made of solid non-combustible
material, set on a firm and level base and should be at
least 125mm (5”) thick. This can include the thick-
ness of any non-combustible floor under the hearth
or non-combustible decorative surface. It must be
capable of supporting the weight of the stove (when
loaded) along with any attached flexible flue liner
which may bear down on the stove. This hearth must
conform to local building regulations which may vary
from country to country.
In England and Wales there is a minimum requirement
for the hearth to project 500mm (20”) in front of any
brick or stone recess and 150mm (6”) at each side of
the recess. The hearth should extend by a minimum
of 225mm (9”) from the front of the stove (which
includes the edge of the ash lip). As a general rule it is
best to extend the hearth to at least 75mm (3”)
beyond the furthest out-swing of the stove door if
possible to avoid any potential live ash held on the
inset door falling on to combustible flooring or floor
coverings. If the top of the hearth and any combus-
tible floor coverings are level with each other then a
retaining fender should be fitted to warn occupants of
the hearth area. Alternatively, a 28mm (1.1”) change
in level provided by a decorative non-combustible
material such as stone, marble, granite, ceramic tiles
etc could be used.
Please note that some materials, such as marble, may
not be suitable when used in a single sheet. This may
prove problematic if, for example, the inset stove is
being installed within an existing fire surround which
features a one-piece back panel which the inset stove
is intended to sit inside. Non-combustible fire
surrounds intended for use with solid fuel open fires
and stoves feature smaller panels pieced together
which allow space for expansion when hot. Your stove
dealer or installer should be able to advise you about
the suitability of an existing fire surround.
The ‘Fireplace’
The stove must be sited within a brick or stone fire-
place recess. It is unsafe to use this inset stove as a
free-standing stove.
The fireplace side and rear walls should be at least
75mm thick and made of non-combustible brick or
stone. Any gaps at the back and sides of the stove
and the fireplace aperture should be filled with non-
combustible insulation material such as rockwool or
vermiculite. This will not only improve the efficiency of
the stove but also help avoid the potential build-up of
combustible soot along the sides – this is an especially
important requirement if you are not using a flue liner.
Inset Stove Fireplace Opening
Your Alpha Inset stove has been designed to fit
relatively easily within a 16” x 22” (400mm x 550mm)
standard builders’ fire opening.
• Redundant back boilers or ‘Baxi’ type ash pits and
air intakes ideally should be removed, filled and
levelled.
• Existing fireplaces and hearths must be made of
non-combustible materials as well as be suitable for
use with a solid fuel stove. For example the hearth
and backplate ideally should be ‘slabbed’ with
concrete and any decorative surface finishes, such as
marble, should be ‘tiled’ to allow for heat expansion.
• Ensure that any existing fire surround or fireplace
back plate you propose to re-use or leave in position is
secure and that any air gaps between it and the back
wall are sealed, particularly around the actual fireplace
opening and the backplate interface. It is important
for safety reasons that this seal is air tight.
• Where possible once the stove position has been
settled upon any significant gaps along the side and
back of the inset stove should be filled with a suitable
inert material such as Rockwool. A vermiculite and
cement mix (6 parts vermiculite to 1 part cement)
can be used for filling large spaces – but under no
circumstances should it be packed against the stove
sides thus limiting the potential for the stove to be
accessed or easily removed at some later point.
Flue Draught
The Alpha Inset has been tested with a flue
draught pressure of 12pa and therefore to ensure
performance which is line with the test results on
page 3 the ideal flue draught pressure should be
approximately 12Pa.
The Chimney, Flue and Flexible Liners
Other appliances should not share or be connected to
the same flue system or chimney.
Generally speaking, the chimney or flue terminal
must be above the height of the apex of the building
and any other obstructions, such as trees, which are
within 3m (10’) of the flue terminal. Failure to do this
could affect the efficiency of the stove and may also
cause unwelcome down draughts which would mean
potentially dangerous flue gases could be emitted into
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