FLUES
Flues should be vertical wherever possible and
where a bend is necessary, it should not make an
angle of more than 45
o
with the vertical. Horizontal
flue runs should be avoided except in the case of a
back outlet from the appliance, when the length of
the horizontal section should not exceed 150mm.
In order to minimise flue resistance and to make
sweeping easier it is recommended to use 2 x 45
o
bends rather than a 90
o
bend.
The flue termination point must be located to min-
imise any wind effects. Wind effects of suction,
pressure zones and turbulence can be created by
the roof and adjacent objects. Wind effects can also
be created by natural land contours.
To minimise the wind effects, the flue termination
point should be located a minimum of 1000mm from
the roof measured vertically and 2300mm measured
horizontally. Where this termination point does not
suffice it may be necessary to extend the flue pipe
so that the termination point is above the apex.
FLUE PIPES
A flue pipe should only be used to connect an appli-
ance to a chimney and should not pass through any
roof space.
Fig.3
Flue pipes may be of any of the following materials:
(a) Cast iron as described in BS 41: 1973 (1981),
or
(b) Mild steel with a wall thickness of at least 3mm,
or
(c) Stainless steel with a wall thickness of at least
1mm and as described in BS EN 10095:
1999 Specification for stainless and
heat resisting steel plate, sheet and strip, for
Grade 316 S11, 316 S13, 316 S16, 316 S31,
316 S33, or the equivalent Euronorm 88-71
designation, or
(d) Vitreous enamelled steel complying with BS
6999: 1989.
Flue pipes with spigot and socket joints should be fit-
ted with the socket uppermost.
CHIMNEY
The stove is a radiant room heater and must be con-
nected to a chimney of the proper size and type. The
chimney must have a cross sectional area of at least
19350 square mm (30 square inches) or a diameter
of 150mm (6 “). The chimney should be checked for
soundness and draught before installation. The
stove must be connected to a chimney with a mini-
mum continuous draught of 12pa. Poor draught will
result in poor performance. Similarly an excessive
draught will result in the appliance over firing or
being difficult to control. An excessive draught may
require a flue draught stabiliser to be fitted. Do not
connect this appliance to a chimney serving another
appliance. The minimum required chimney height is
4.5 metres from the floor on which the appliance is
installed. An existing masonry chimney should be
inspected and if necessary, repaired by a competent
mason.
If the stove is fitted in place of an open fire then the
chimney should be swept one month after installa-
tion to clear any soot falls which may have occurred
due to the difference in combustion between the
stove and the open fire.
DOWN DRAUGHTS
However well designed constructed and positioned,
the satisfactory performance of the flue can be
adversely affected by down draught caused by near-
by hills, adjacent tall buildings or trees. These can
deflect wind to blow directly down the flue or create
a zone of low pressure over the terminal. A suitable
anti-down draught terminal or cowl will usually effec-
tively combat direct down blow but no cowl is likely
to prevent down draught due to a low pressure zone.
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