Flue Liner: What Is It and What Does It Do?

If you have a chimney, then you may have heard advice recommending that you install a flue liner in your home to save on energy. While perhaps not something that the Victorians would ever have used, the flue liner is in fact a building requirement in some states, and others control the way that it is installed and used. If you have never heard of a flue liner before, it is possible that your chimney already has one installed as most homes have been built with one already.

What Is a Flue Liner?

A flue liner is installed into the chimney, usually from above, and acts as an insulator, preventing cold air from traveling down the chimney. In this way, it is an energy saving device. There are many different types of flue liner, from old fashioned clay lining which was not always well installed, to modern metal or fabric versions. Which kind of flue liner you have depends very much upon the age of the building, cost, and whether you have a gas fire or a wood stove. There are three main type of liner which are common on the market. The Refractory lining, which is a rubber tube rather like a balloon which is cast into the chimney and then inflated (using an air pump not human lung power). This is then sealed into place using a stone mix in order to secure the tubing. Metal liners are another type and can be used in gas or wood burning stoves, where there is heat and some toxic fumes. These are installed much like the refractory, by being dropped down the chimney and then spaces filled in with stone mixes. The last version is a solid liner, which is only used if the stack can be shown to be straight, or if it is being rebuilt. It is made of concrete, and has the advantage of not allowing water into the flue.

What Does a Flue Liner Do?

Flue liners are there to protect you from smoke. Most lining in chimneys is old, and liable to produce smoke in the room when the fire is lit. Heat on old chimneys can cause the motor to erode, and will also cause soot to form again on the bricks. A flue liner improves the state of the brick, and ensures that smoke travels up and into the air, rather than into the room where it can be inhaled. The lining also has the value of insulating the chimney, so that during cold weather most of the heat is forced into the room, rather than escaping through the chimney, and the bricks themselves do not transfer cold into the room. The flue liner will also prevent water from condensing on the chimney, damaging bricks and even roof tiles. It is necessary to have a liner when you start using a more efficient heating system combined with an aging brick chimney.