Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 25·2.16-2.17
Interaction of mechanical extract ventilation and open-flued combustion appliances - general principle
Extract fans lower building pressure and can cause spillage of combustion products from open-flued appliances. Combustion appliances should operate safely whether or not the fan is running.
Extract fans lower the pressure in a building and this can cause the spillage of combustion products from an open-flued appliance.
In a building where it is intended to install an open-flued appliance and an extract fan, the combustion appliance should operate safely whether or not the fan is running. To minimise the risk of spillage of flue gas the following provisions should apply –
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