The glass on your wood-burning stove is turning black: here’s how to prevent it

"We chose a high-end wood-burning stove, with a large glass surface to enjoy the flames. It was installed by a professional. But we are very disappointed! After each fire, it’s a real chore to clean, the glass darkens rapidly. We end up hesitating to light a fire... Do you have a solution?"

Every situation is different, so it’s difficult to diagnose the problem remotely. There are 3 main reasons why the glass in a wood-burning or pellet stove might turn black. Once the cause or causes have been identified, the problem should be easy to resolve.

Reason 1: There isn’t enough air circulating near the glass panes

• Two tips:
• - Leave a gap between the wood and the glass.
• -  Check that the stove’s air inlets are correctly adjusted.
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Reason 2: There is too much smoke in the stove, the draught is insufficient

There are many factors that affect the quality of the draught, which is essential: the size of the flue, the cleanliness of the flue (make sure the sweeping is done properly!), the height of the chimney stack, a flue that is too short or has elbows. We recommend that you check this with your installer.

However, you could try this:

• - Get your fire going to warm up the room quickly. A lack of draught can be caused by very cold air in the flue. You can light the fire with the door ajar, keeping an eye on it. Once you have a good blaze going, leave the stove’s air intake control open for about 15 minutes. Then, close it progressively.
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• - Do not run your appliance on low heat: the glass gets less dirty when the flame is high. There may not be enough fresh air coming into the fireplace. If the wood burns better when a window is left slightly open near your stove, it is because it needs a certain amount of oxygen to function properly, which it cannot find in the room where it is installed (too small, too well-insulated). All you need to do is install an external air intake, cut through the wall and connected to the stove using a combustion air intake kit.
•  

Reason 3: The fuel is not of good quality

The biggest enemy = damp wood! Not only do your glass become blackened but you also get poor combustion and your appliance isn’t performing at its best. Did you know that wood cut more than 2 years ago isn’t necessarily dry if it’s been stored incorrectly?

- Try lighting a fire using certified firewood: this is made from logs and branches, then dried in drying chambers until its moisture content falls below 20%. The less moisture a log contains, the higher its calorific value.

- You could also try densified logs. Made by compressing sawdust and other by-products from sawmills, they are particularly efficient, as their moisture content is between 7% and 10%. They are ready to use, just like wood pellets, which have a similar calorific value.