A Class 1 chimney is an upright structure which contains one or more flues. A flue is a chamber in the chamber that contains the products of combustion otherwise known as flued gases. Each flue is connected to an individual fireplace. A flue works because warm air is lighter than cold air, thus the warm air rises and displaces the cold air. This process creates a ’flue draught’ or draw’ and ensures flued gases are safely emitted into the atmosphere.
If the flued gases are allowed to cool down then condensation can occur in the flue. If you are burning wood then this can cause tarring of the flue. This tarring can run back down to the fireplace or permeate through brickwork causing staining. Please check the Cleaning Your Chimney link.
A Class 1 chimney flue is also known as a ‘conventional’ flue. A Class 1 chimney is easily recognised by a brick or stone built stack sited on the roof, and by one or more chimney pots (normally terracotta) projecting from the stack.
