9
Prior to installation
The exhaust air is discharged upwards through a
ventilation shaft or directly through the outside wall
into the open.
Exhaust air should neither be directed into
a smoke or exhaust flue that is currently used for
other purposes, nor into a shaft that is used for
ventilating rooms in which stoves or fireplaces are
also located.
Exhaust air may be discharged in accordance
with official and statutory regulations only (e.g.
national building regulations).
Local authority regulations must be observed when
discharging air into smoke or exhaust flues that are
not otherwise in use.
When the extractor hood is operated in exhaust-
air mode simultaneously with a different burner
which also makes use of the same chimney
(such as gas, oil or coal-fired heaters, continuous-
flow heaters, hot-water boilers) care must be taken
to
ensure that there is an adequate supply of
fresh air
which will be needed by the burner for
combustion.
Safe operation is possible provided that the under-
pressure in the room where the burner is installed
does not exceed 4 Pa (0.04 mbar).
This can be achieved if combustion air can flow
through non-lockable openings, e.g. in doors, win-
dows and via the airintake/ exhaust-air wall box or
by other technical measures, such as reciprocal
interlocking, etc.
If the air intake is inadequate, there is a risk of
poisoning from combustion gases which are drawn
back into the room.
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An air-intake/exhaust-air wall box by itself is no
guarantee that the limiting value will not be ex-
ceeded.
Note: When assessing the overall requirement, the
combined ventilation system for the entire house-
hold must be taken into consideration. This rule
does not apply to the use of cooking appliances,
such as hobs and ovens.
If the exhaust air is going to be discharged into
the open, a telescopic wall box should be fitted into
the outside wall.
For optimum extractor hood efficiency:
Short, smooth air exhaust pipe.
As few bends in the pipe as possible.
Diameter of pipe to be as large as possible and
no tight bends in pipe.
If long, rough exhaust-air pipes, many pipe
bends or smaller pipe diameters are used,
the air extraction rate will no longer be at an
optimum level and there will be an increase
in noise.
The manufacturer of the extractor
hoods accepts no liability for complaints
which can be attributed to the design and
layout of the pipework.
Exhaust-air mode
