Chimney sweeping is an age old profession introduced to remove soot from a chimney, initially using young children to climb the chimney and brush the soot or scrape tar from the walls. This was replaced by the use of rods and brushes in the early 18th century which are still used today.
In simple terms, the smoke that comes from a fire carries non combusted material such as carbon (soot). As smoke works its way up the flue carrying the soot, it deposits itself to the lining of the flue until eventually there is quite an even coating. Because the soot has not combusted, it is still flammable. Therefore it is important to remove it, to reduce the occurrence of a chimney fire.
Also, the more soot that is deposited on the wall of a flue will eventually reduce the size of it, making a fire or appliance burn less efficiently. This starts a spiralling circle, as the less efficient a fire is, it smokes more. This creates more soot and makes the fire even less efficient and so on until the flue gets completely blocked! This is more common in wood burners where a flue liner can be as small as 5” in diameter.
A chimney may be blocked by other means, such as a birds nest, builder’s rubble, animals or anything else that decides to reside in a nice warm place! Sometimes this can be avoided by having a bird guard fitted, but if not, it is always advisable to have a chimney swept before the burning season in order to make sure the smoke can evacuate from the house efficiently via the chimney.