You need to check the condition of the chimney and, if necessary, reseal the chimney door and properly fit the flue pipes and replace any damaged sections.

Discuss the cause with a chimney sweep or heating engineer and take all recommended measures, e.g., clean the chimney, remove the flue reduction, increase the height of the chimney, ensure sufficient air intake into the room.

Increase heat output in these conditions, i.e., open the primary and secondary air intake – regulation to “full”.

The most important thing is to only use dry wood with a moisture content not exceeding 20%. It is not possible to achieve high-quality combustion and the required heat output using wet fuel.