When wood is burned slowly to make a smoky fire, the smoke can condense on the cool inner surface of the chimney producing creosote deposits. Creosote is a highly flammable material. If it ignites at the base of the chimney, it can produce a raging fire that travels up the chimney causing extremely high temperatures as it spreads. The high temperatures can damage the clay liners in a masonry chimney or the metal liner in a factory-built chimney. Although 650°C chimneys can withstand chimney fire temperatures, the heat causes extreme stress in the chimney.
Chimney fires are the result of poor appliance firing techniques combined with a lack of proper chimney maintenance. When wood-burning appliances are operated properly, some creosote may still be deposited but it will be of a less combustible type. Instead of the black, tarry type of creosote that results from smouldering fires, the creosote that results from proper firing is soft, flaky and dark brown in colour. Chimney fires can be prevented. Chimneys should be checked for creosote deposits regularly until you know how quickly it builds up in your chimney. Conventional wood stoves can produce creosote quickly because they are unable to burn the wood as completely as the advanced designs. In severe cases, enough creosote to sustain a damaging chimney fire can be deposited in only a few days. The newer, low-emission wood stoves burn the wood so completely that, when they are operated properly, their chimneys normally need cleaning only once a year.
Never assume that the chimney is clean. Check it regularly to be certain, especially during the spring and fall seasons. Visit www.burnitsmart.org for more information.
THIS MESSAGE HAS BEEN BROUGHT TO YOU BY THE DISTRICT OF TUMBLER RIDGE PROTECTIVE SERVICES PROGRAM.