Using a cooker hood at the same time
as another heating appliance that
depends on the air from the room
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Great care should be taken when
using the cooker hood at the same time
and in the same room or area of the
house as another heating appliance
which depends on the air in the room.
Such appliances include gas, oil, wood
or coal-fired boilers and heaters,
continuous flow or other water heaters,
gas hobs, cookers or ovens which draw
air in from the room and duct exhaust
gases out through a chimney or
extraction ducting.
When used in exraction mode, with or
without an external motor, the
appliance draws air in from the room in
which it is installed and from
neighbouring rooms.
If there is insufficient air, an
underpressure will occur. The heating
appliance may be starved of oxygen,
impairing combustion.
Harmful gases such as carbon
monoxide could be drawn out of the
chimney or extraction ducting back
into the room with potentially fatal
consequences.
In order to ensure safe operation, and
to prevent gases given off by the
heating appliances from being drawn
back into the room when the extractor
and the heater are in operation
simultaneously, an underpressure in the
room of 0.04 mbar (4 pa) is the
maximum permissible.
Ventilation can be maintained by air
inlets which cannot be blocked, in
windows, doors and outside wall vents,
or by other technical measures, such
as ensuring that the extractor can only
be switched on when the heating
appliance is switched off or vice-versa.
A ventilation brick alone is not generally
sufficient to ensure safe ventilation.
The overall ventilation condition of
the dwelling must be taken into
account. If in any doubt, the advice
of a competent builder or, for gas, a
"Corgi" installer, must be sought.
Operation
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