Viessmann Vitoladens 300-C Installation And Service Instructions Manual page 4

Safety instructions
Safety instructions
Extractors
Operating appliances that extract air to
the outside (extractor hoods, extractors,
air conditioning units, etc.) can create
negative pressure. If the boiler is oper-
ated at the same time, this can lead to a
reverse flow of flue gas.
4
(cont.)
Danger
The simultaneous operation of the
boiler and appliances that extract
air to the outside can result in life
threatening poisoning due to a
reverse flow of flue gas.
Fit an interlock circuit or take suita-
ble steps to ensure an adequate
supply of combustion air.