Looking after your chimney
A chimney safely removes the products of combustion from the fireplace or appliance to outside without causing danger to the occupants of the house or setting the house on fire.

For any fire to work successfully and efficiently, it must be connected to a sound chimney and correctly sized flue.

A chimney works because hot air rises and always moves from high to low pressure. Factors such as running the appliance at a very slow rate, or cold air leaking into the flue, will cool the gasses and affect the performance of the chimney. 

In houses built since 1965 (when Building Regulations were introduced) all flues must be built with liners during their construction. This is usually done with clay liners, which should last the life of the building. However, in houses built prior to 1965, lining was less common. Flues were usually “parged” (rendered) on the inside with lime mortar. This parging suffers attack from acids and tars produced during combustion, and gradually deteriorates. The flue is then in poor condition, often leaking fumes or tars into the walls or other parts of the building. Sadly, many houses built since 1965 suffer similar problems due to badly installed flue liners and need further attention.

Understanding the differences between a chimney and flue

• Chimney – A chimney is the structure surrounding one or more flues.
• Chimney Terminal – This is the pot, cowl or other method of finishing the top of the chimney.
• Flue – The flue is the void or passageway through which the products of combustion are removed from the fire to the outside.
• Flue Liner – The flue liner is the material used to form the flue or flues within a chimney.
• Flue Pipe – is a metal pipe used to connect an appliance to the flue in a chimney.

Lining your chimney

There are a number of reasons why an old chimney may need lined:

• The flue is leaking smoke and fumes into other rooms or parts of the building.
• Condensates or tar are seeping through the chimney walls causing staining, either inside or outside the building (a common problem with wood burning stoves)
• The flue is too large for the type of fire or appliance being used.
• The flue is too cold, particularly if on an outside wall, and is not drawing properly.
• If the chimney was built since 1965, but with the liners fitted the wrong way up, tar and condensate leakage may occur.
• The old flue surface is eroded and rough, causing frictional resistance to the flow of the gasses resulting in poor updraught.

Before any new lining is installed it is essential to have the chimney swept to remove all soot and tar deposits.

Several methods are available for inserting a lining into an existing flue but by far the most common and cost effective method we use is a flexible metal liner in a continuous length lowered down the chimney.

There are two distinct types of flexible metal liners available and it is very important to distinguish between them.

• Solid fuel flue liner – This is a double-skinned liner made from an extremely high quality stainless steel and is smooth on the inside, corrugated on the outside and must be installed the correct way up. It is specifically designed for relining flues for solid fuel and wood.
• Gas flue liner – A light gauge single skin liner commonly available in coils. It cannot be used for solid fuel or wood burning appliances, or open solid fuel effect gas fires. Readily available sizes are lOOmm (4"), 125mm (5"), and 150mm (6") diameters. The minimum size permitted for closed (glass fronted) gas fires and stoves is 125mm (5")

Gibson & Goold does not offer any chimney services directly but we have been impressed by the professional work from Old Mill Chimneys, Clydebank.

As a fellow family-run business with over 60 years experience they can offer in-depth experience with the latest operational techniques. Wherever chimney expertise is required – in design, construction or sweeping – Old Mill Chimneys has the qualified team with the answers.

Call on their services for domestic, commercial, large or small jobs on every type chimney and flue at locations all over the country daily.

Call Wendy or Marina to arrange a free estimate or appointment
01389 872436 or visit their site at www.scottishchimneys-omh.com