As your wood fire burns, chemical breakdown occurs, resulting in byproducts being released. What most people notice is the smoke, but it’s what’s hidden in the smoke that can cause a problem. When the fire burns the chimney helps to vent harmful gases such as carbon monoxide, particulate pollution, soot, and creosote. Carbon monoxide is a dangerous gas that can cause severe injury and death, and soot and creosote can cause chimney malfunction when they are not cleaned away.
What is Creosote?
Creosote is different than soot. It is made up mostly of tar and sticks to the sides of the chimney flue as it rises. Creosote is released every time wood is burned, but wood that is properly seasoned and burns completely will create less creosote. Similarly, a chimney that is maintained properly, and functioning correctly will result in less creosote left in the flue.
When creosote is not cleaned away, or when an excessive amount is released because of bad burning practices or maintenance, it builds up in the flue. When creosote buildup becomes extreme it’s called a level three buildup or “glazed creosote” because it has a glossy appearance and is hardened. This level of creosote is more difficult to remove and is extremely dangerous.
Glazed Creosote and Flue Fires
Glazed creosote is highly flammable because it is a concentrated fuel. It reaches this state through a distinct and preventable process:
1. Creosote builds up in the flue
2. Creosote is heated by the fire
3. Moisture evaporates, leaving behind concentrated fuel (tar)
4. Creosote hardens, obstructing airflow
5. As airflow slows, heated air and sparks stall in the flue, fuel can ignite
6. Resulting “creosote fire” is quick and devastating
The biggest risk to your chimney when it comes to creosote is fire. Many chimney fires go undetected, but a creosote fire has the potential to be devastating. To ignite, it must reach temperatures in excess of 1000 degrees, which is possible when airflow is compromised. Fire is the most devastating risk of creosote in the chimney, but a drop in efficiency can affect your home as well. Smoke unable to move out the chimney will move into your house. An inefficient chimney will also result in wasted wood, make it difficult to light and maintain a fire, and will need routine services more frequently.
Avoid these problems and make sure you schedule a chimney inspection and sweep to keep your chimney working for you. At Mr. Smokestack Chimney Service we offer chimney sweeps and inspections year-round so that our customers in Raleigh and surrounding areas can take care of their chimney maintenance when convenient for them. It’s our goal that every home with a chimney is safe and warm this winter, so call us for your chimney needs now.
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