From time to time you may experience difficulties with your wood burner, which will often be indicated by smoke leaking from the stove. This can be due to a fault with the chimney, but it can occur for other reasons too. The following guidelines should help you to spot any problems and put them right.
The Stove Door
If the door to your wood burning stove is not airtight and smoke is leaking round the sides of the door, check to make sure that none of the gaskets are broken. Gaskets can be purchased from stove suppliers and replaced using heat resistant cement to fix them into position. Likewise, the glass can be replaced if it is damaged or, in some cases, the whole door may need to be replaced. A qualified installer will be able to advise you, but if you have spotted the cause of the problem yourself it is possible to obtain all of these parts from a specialist stove supplier.
Smoking Chimneys
To find the cause of your smoking chimney you firstly need to identify whether it is smoking continuously or whether the smoking occurs intermittently. When a chimney gives off a constant stream of smoke into the room this can be due to a number of causes:~
Quality of Wood – If you are using the wrong type of wood or the wood has not been seasoned, this can make the wood smoke excessively whilst burning. Generally, the types of wood most suitable for wood burning stoves are ash and beech whereas pine and spruce are the least suitable.
Chimney Blockage – It is important to have the chimney swept twice a year to prevent a build up of soot and tar. You can spot these by examining inside the chimney once it has cooled, using a torch. You may find that there is something else blocking the chimney such as a bird’s nest. Once you have moved any obstructions you should find that your fire continues to function normally.
Poor Ventilation – A stove needs ventilation so that the air movement can carry smoke through the chimney. If your room is not well ventilated it is best to have a stove ventilator fitted close to your wood burning stove. Poor ventilation in a room with a wood burning stove can be dangerous.
Presence of another Chimney – This can affect the performance of your wood burning stove as the other chimney will also pull in air, meaning less air movement for your wood burner. For this reason you should block off any chimneys that aren’t in use. If you are using stoves with both chimneys then try shutting the air vents and door to the other stove, or in the case of an open fire, shut the back baffle. Extractor fans in the home can affect the stove in the same way so switch them off if they are causing a problem.
Poorly Insulated Chimney – It is important to have your chimney insulated as this will retain the heat. Because heat rises it will improve the draw allowing any gases and smoke to escape through the chimney.
Faulty Chimney Cap – The chimney cap or cowl is fitted on the top of the chimney with mesh at the sides for the smoke to escape. If the cap is damaged then it won’t do its job of keeping out rain and debris, which will cause the chimney to smoke. Even if the chimney is not being used, a cap should be fitted to prevent damp getting inside.
Large Fireplace Opening – If your fireplace opening is too large this can cause problems with smoking. In this case you should block off part of the opening using a non-combustible material such as a metal plate.
Chimney Size – If your chimney is not tall enough then you won’t get sufficient draw to allow the smoke to escape. You can either have it built so that it is higher or replace the chimney pot with a taller one. In some cases it is the width of the chimney pot or the cowl that is too small. It is best to have your chimney checked by a qualified installer to make sure that it is of a sufficient size for use with a wood burning stove.
Strong Winds – Strong winds can affect the air pressure outside the chimney causing air to be sucked down the chimney and released in an area where the pressure is lower. Although there is no real solution to this problem, it is a rare occurrence.
Downdraught
If your chimney lets out intermittent puffs of smoke into the room, this is known as downdraught. A downdraught is caused either when the chimney isn’t high enough, or it is surrounded by high buildings or trees, as these affect wind currents. This can be solved by making the chimney higher or fixing an anti-downdraught cowl.
Chimney Fires
Chimney fires are dangerous and are usually caused by a build-up of tar inside the chimney. This is another important reason to have the chimney swept regularly and have it insulated. A damaged chimney will also encourage tar to collect in the crevices so check that the mortar between the bricks isn’t broken.
The Flue
The flue extends out of the stove pipe and into the chimney so a faulty flue can cause similar problems to a faulty chimney. If smoke is leaking from the flue itself, then this could indicate that there is a break in the flue or one of the seals is leaking. Heat resistant cement can be used to reseal the joins between the sections of flue pipe. However, if the pipe itself it damaged then it would be best to replace that section.
It is essential that you carry out regular maintenance checks on your wood burning stove, the chimney and the flue. Not only will this help the stove to run smoothly but it will ensure that it remains safe to use.