Casing of chimneys

What causes the corrosion of chimneys?

Chimneys made of bricks or concrete components are sensitive to humidity. If their upper temperature is lower than the dew point temperature of the combustion product during usage, the smoke gas condenses and moisture infiltrates into the wall.

The impregnated wall does not keep the plaster so that it can peel off in big parts blocking the route of the combustion product. The carbon monoxide gets back to the living space this way.

The first sign of the saturated wall is the brown discolouring on the external brickwork.
Dew point temperature: a kind of temperature in case of which the vapour volume in air reaches the quantity belonging to the given temperature of air that the air can take on this temperature in shape of steam, becomes saturated. Quantity of vapour above this condenses.