If the room where the cooker hood is to be
used contains a fuel burning appliance such as
a central heating boiler, then its flue must be of
the room sealed or balanced flue type.
If other types of flue or appliances are fitted
ensure that there is an adequate supply of air
to the room.
The cooker hood ducting (extraction version)
must never be connected to central heating
flues, radiators or water heaters etc.