Miele DA 396-6 Operating Instructions Manual page 8

Warning and Safety instructions
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 rangehood 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 or outside wall vents, or by other
technical measures, such as ensuring that the rangehood 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 qualified gas fitter must be sought.
The rangehood must not be used in recirculation mode, where the
air is directed back into the room where it is located, at the same
time as a heating appliance which depends on the room air.
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