Soot or charcoal is caused by inefficient and oxygen-poor combustion in boilers that work with solid fuels (biomass) or heavy liquids, and can even happen with natural gas or LPG.
Soot must be cleaned at the base of the chimneys so that they do not obstruct the smoke outlet, and in the inlet holes and grilles, to ensure efficient ventilation.
The build-up of soot can be prevented by adjusting the burners and performing annual maintenance of the burner and combustion checks.
The oxygen probe burners in ATTSU boilers automatically adjust the air/fuel ratio, thereby preventing oxygen-poor combustion.