BORETTI CFBG902AN3 Instruction On Mounting And Use Manual page 14

Caution:
Gas hobs produce heat and humidity in the environment in which they are
installed. Ensure that the cooking area is well ventilated by opening the
natural ventilation grilles or by installing an extractor hood connected to an
outlet duct that vents to the outside.
Caution:
If the hob is used for a prolonged time it may be necessary to provide
further ventilation by opening a window or by increasing the suction power
of the extractor hood (if fitted).
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