What to do if soot catches fire in the chimney?

Is it reasonable to assume that a simple accumulation of soot in a chimney could cause a fire? It turns out that this is a common occurrence. After all, soot, which is 98% carbon, is practically indistinguishable from coal. Let’s see what happens.

Imagine a situation: you haven’t cleaned the chimney of your furnace or boiler in a while and you notice that the airflow has decreased. This is the first sign that carbon deposits have reduced the space for smoke. To increase the draft, open the ash pan and the valve, and that’s where the problem begins. As the oxygen content in the pipe increases, the temperature rises rapidly, and the carbon particles absorbed by the increased draft ignite the soot, which may go unnoticed. Often, the first signs of impending trouble are a buzzing sound in the chimney and sparks flying from the chimney.

Regarding the physics of this process, it should be noted that the combustion temperature of soot reaches +1200°C, which leads to the destruction of the flue and the possible ignition of surrounding materials. In one case reported on social media, soot ignited in an asbestos-cement pipe while the owner was away, resulting in an explosion that destroyed the pipe.

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