Fire district urges flue pipe, chimney checks

As temperatures threaten to drop below freezing later this week, many homes may rely on their chimneys or wood-burning stoves for warmth. Boone County Fire Protection District Battalion Chief Gale Blomenkamp urges people using those, though, to get professionals to check their system before winter use.

“They inspect that flue pipe to make sure that all the seams are together, because if you have a seam or a joint that comes apart, and you build a fire in your fireplace, that allows the heat to escape your flue pipe into your attic space,” Blomenkamp said.

Nearly every house utilizes a flue pipe, the metal or PVC structure that carries heat and smoke from a boiler, gas-powered appliance or chimney up and out of the home. Blomenkamp said pipes from water heaters often don’t experience temperature-specific damages, but items less used, like chimneys, run the risk of cracking the pipes with the changing temperatures. Blomenkamp likened a chimney sweep inspecting your system to “preventative maintenance,” such as work done to cars in the winter.

“You start your fireplace for the first time of the season, run a super-hot fire, it expands, then it shrinks back down,” Blomenkamp said. “And over time, those seams can come apart. So that’s why we strongly encourage people to have their flue pipes inspected on a yearly basis prior to using that fireplace or that wood-burning stove.”

Blomenkamp said that heat can begin smoldering wood joists nearby, or insulation that gathers near the pipe. Flue pipes can build up creosote from smoke, and that material can catch fire, causing flue fires. Blomenkamp said the district often can extinguish fires while in the pipe or chimney, but severly cracked pipes can ignite the wood around it.

“It almost turns into charcoal over time, if it’s a small leak or heat leak,” Blomenkamp said. “But if it’s a severe fracture or crack in that flue pipe, you can get significant heating that leaves that pipe, then catches your structure of your house on fire.”

Hard wood like ash and oak burns hotter than soft wood, like pine, Blomenkamp said. Hotter fires can reduce the likelihood of creosote build-up, while long-smoldering fires, such as those in wood-burning stoves overnight, cause the most creosote accumulation.