Miele DAR 1120 Operating And Installation Instructions page 7

Using at the same time as other heating appliances that depend on the air
from the room
 Warning - danger of toxic fumes!
Great care should be taken when using the rangehood 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 cooktops, or
ovens which draw air in from the room and duct exhaust gases out
through a chimney or extraction ducting.
When used in extraction mode, with or without an external motor
fitted, or in recirculation mode with a recirculation box installed
outside the room, 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 will be starved of oxygen, impairing combustion.
Harmful gases could be drawn out of the chimney or extraction
ducting back into the room, with potentially fatal consequences.
Warning and Safety instructions
7