Flue Options for Wood Burning Stoves

A wood burning stove must have a flue in order to direct the smoke to the chimney so that it escapes outside the building. The stove pipe that is connected to the wood burner is not suitable to be fed through the wall or ceiling of the home and it must there before attached to a flue.

Flues must be made from a material that is suitable for wood burning stoves. If the building already has a chimney then the chimney can be fitted with a flue which is suitable for a wood burner. By using a flue you can avoid the risk of tar deposits collecting in the chimney as proper insulation will keep the escaping gases hot. Therefore, suitable materials for insulating flues are either steel or lightweight aerated concrete. There are different types of flues that are used for wood burning stoves.

Single Skin Flues

A single skin flue pipe is usually used to connect the stove pipe to the chimney because it can allow some heat back into the room and is usually better in appearance than double skin insulated flue. However, it must not extend into the chimney interior because it will allow the escaping gases to cool, which will increase the risk of tar deposits inside the chimney.

The flue consists of various parts, which can have elbows and bends allowing you to direct the smoke to the chimney, and special cement should be used to join each piece. They are usually made from stainless steel but can be covered with a special enamel to enhance their appearance. The enamel is commonly black in a choice of either glossy or matt.

Double Skin Insulated Flue

A double skin insulated flue can be used with a wood burning stove without any need for a chimney as it can safely pass through walls and roofs. This type of flue will ensure that any escaping gases remain hot, which will prevent the fire hazards associated with tar deposits. It is possible to use only double skin flue piping, but if it is to be attached to single skin flue piping it is best to be aware that there is a difference in diameter. Therefore, it is best to do this only in an area where the change of piping will not be visible, for example, close to the ceiling.

Again this type of flue consistors of various parts of tubing which are welded together. It must also have at least one plate or bracket to support the flue, and for long flues several subsidies must be used with at least one for each two metre length of flue. Double skin flues can be boxed in if they are in a storage area, such as a loft, to avoid items being leant against them by accident.

Recommended Sizes

There are specific regulations relating to flue sizes and the way in which they are fitted. The diameter of the flue must be larger than the stove outlet or stove pipe. The recommendation for the diameter of flues is at least 150mm for wood burning stoves in accordance with Government guidelines.

There are also guidelines relating to the distance of the flue outlet from the roof of a building. This is because the gases must be able to escape so that they do not cause a fire hazard. These distinctions depend on the pitch of the roof and where the flue termination is in relation to the ridge of the roof. Also, the flue outlet should not be too near to roof windows or neighboring buildings.

Single skin un-insulated flue pipe should not be placed too near to flammable materials. The minimum requirement is a distance of three times the diameter of the pipe. In terms of the length of single skin flue pipe that is used, it is generally recommended that this is limited because the longer it is the more it will allow the flue gases to become colder resulting in a build up of tar.

Flue Liners

Flue liners can be placed inside chimneys for use with a wood burning stove. These should be capable of withstanding the high temperatures that are produced by wood burners. They should also be flexible enough to be rolled through a chimney and should withstand with any damp conditions inside the chimney. For these reasons, flue liners for use in a domestic dwelling are typically made from stainless steel that is a minimum of 316 grade. It is also possible to buy flue liners that are made from higher grade stainless steel or liners that are made from concrete. However, concrete liners are a more permanent solution, and are more expensive to fit due to the labor involved.

It is important to remember that an incorrect or badly fitted flue or flue liner can cause your stove to function incorrectly and therefore present a fire hazard. Therefore, it is always best to consult an expert if you are installing or replacing a flue for your wood burning stove as they will be aware of up-to-date regulations and guidelines.