What Purpose Does a Chimney Liner Serve?

A chimney liner, usually fitted inside the chimney of a home heated by gas, wood or oil, provides a channel for smoke, heat and fuel by-products to escape.  A chimney liner keeps the heat of the flue inside the chimney to avoid overheating of the nearby combustible materials such as house framing or walls. Excessive heating through the flue gases could also lead to a fire. The liner also prevents carbon monoxide, smoke, moisture and toxic materials from leaking through the chimney in to home. A masonry chimney usually has a liner made of clay tiles.

Till the mid 1900s, a vast number of homes were without any type of chimney liner. Up until the 1940’s the chimneys had flue walls constructed with mortar and bricks which provided protection against leakages.

In modern times, nearly all homes are constructed with an in-built chimney liner. Government building codes require the installation of chimney liner during new construction or home renovation.  All the locales have the regulation mandating installation of the liner, though laws vary state by state and from country to country. Chimney liners can be categorized as clay, metal and a version which is cast in the chimneys.

Clay or ceramic tiles are widely used in the construction of chimney liners as they are relatively inexpensive. For chimneys that serve as a decorative element to the house and do not function as a furnace, clay is the preferred choice for chimney liners. Clay tiles should not be used if wood, gas or oil stoves are used as the inside temperature of the chimney can be very high. Clay tiles are not good heat absorbers and transfer heat along the chimney length. In event of a fire, clay tiles can easily sustain breakages, cracks or may shatter.

Chimney liners need to be regularly inspected and checked for the overall health of the house as well as the well-being of inhabitants. It might look strong and sturdy form the outside but from inside, the situation might be totally different.  A chimney liner might have broken, cracked or missing tiles. These need to be replaced.  A cracked clay liner can lead carbon monoxide to leak into the house. Cracks in the liner can also cause the apparatus to overheat which can lead the nearby combustible materials to heat to a dangerous extent.

This is why you should regularly examine and check your chimney liner to avoid any damage. Replace it before using the appliance connected to the flue again.