Miele DA 422-4 Operating And Installation Manual page 7

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 cooker
hood and the heater are in operation
simultaneously, an underpressure of
0.04 mbar (4 pa) is the maximum
permissible in the room.
Ventilation can be maintained by air
inlets which must not be blocked, in
windows, doors and outside wall vents,
or by other technical measures, such
as ensuring that the cooker hood 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 (GasSafe
registered in the UK) must be
sought.
Warning and Safety instructions
7