Fig.5
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 effectively combat direct down blow but no
cowl is likely to prevent down draught due to a low
pressure zone. (See Fig.6)
Fig.6
Direction of wind
Pressure zone
Direction of wind
Suction zone
Pressure zone
Direction of wind
Suction zone
Pressure zone
Suction zone
Note:
There must not be an extractor fan fitted in the
same room as the stove as this can cause the
stove to emit smoke and fumes into the room.
VENTILATION & COMBUSTION AIR REQUIRE-
MENTS
It is imperative that there is sufficient air supply to
the stove in order to support correct combustion.
The air supply to this appliance must comply with
current Building Regulations Part J, Heat Providing
Appliances. If another appliance is fitted in an adja-
cent room it will be necessary to calculate an addi-
tional air supply.
All materials used in the manufacture of air vents
should be such that the vent is dimensionally stable,
corrosion resistant, and no provision for closure. The
effective free area of any vent should be ascertained
before installation. The effect of any grills should be
allowed for when determining the effective free area
of any vent.
Air vents should be positioned so that they are not
liable to blockage.
Air vents direct to the outside of the building should
be located so that any air current produced will not
pass through normally occupied areas of the room.
An air vent outside the building should not be locat-
ed less than the dimensions specified within the
Building Regulations and B.S. 8303: Part 1 from any
part of any flue terminal. These air vents must also
be satisfactorily fire proofed as per Building
Regulations and B.S. 8303: Part 1.
Air vents in internal walls should not communicate
with bedrooms, bedsits, toilets, bathrooms or rooms
containing a shower.
Air vents traversing cavity walls should include a
continuous duct across the cavity. The duct should
be installed in such a manner as not to impair the
weather resistance of the cavity.
Joints between air vents and outside walls should be
sealed to prevent the ingress of moisture. Existing air
vents should be of the correct size and unobstructed
for the appliance in use.
If there is an extraction fan fitted in adjacent rooms
where this appliance is fitted, additional air vents
may be required to alleviate the possibility of spillage
of products of combustion from the appliance/flue
while the fan is in operation. Refer to B.S. 8303 Part
1.
9
