What is downdraught?
Downdraught is when air is blown back down the chimney, preventing smoke and gases from your woodburning or multifuel stove from rising and being released out of the chimney. The main sign of downdraught is excessive smoking of your stove – you will be able to see the smoke struggling to exit out of the stove via the flue pipe , meaning a firebox full of smoke.
What causes downdraught?
Downdraught primarily happens because a chimney or flue supplies is not tall enough. Tall structures in the nearby area such as buildings or trees can also cause downdraught, as they can affect wind currents.
It is important to consider other issues that could be causing smoky fires and eliminate these first;
• Burning wood with too high a moisture content.
• The flue or chimney has not been warmed sufficiently with kindling/paper before adding large logs to the fire, which affects the draw.
• Blockages in the chimney.
• If the smoke is coming out of the door or the stove collar it is highly likely that the rope/fire cementseals need replacing.
If you have a masonry chimney stack, an expensive option would be to increase the height of the stack.
If you have a twin wall flue system, the height can be increased by adding an extra length.
An option for both of these types of flue installation is to have an anti-downdraught chimney cowl fitted to the top of the chimney/flue system which can be found in our flue supplies store. The compact and aerodynamic shape of this type of chimney cowl makes it perfect for combatting downdraught.
If you have any questions about this article or about flue systems in general, please contact us.
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