This time of year is when you should clean your chimney — not for Santa Claus’ sake, but to prevent a flue fire.

The flue, or the chamber in a fireplace’s chimney stack or the vent connected to a wood stove, can catch fire if creosote builds up in the interior.

“Inside a chimney, it’s pretty violent,” said Dave Howe, a Bend Fire Department battalion chief.

Creosote, or a gooey, crusty resin, is made up of burnt wood particles that float up from a fire and condense on the flue and chimney walls, Howe said. When wood burns at too cool a temperature or smoke rises too slowly a speed, a dangerous accumulation of creosote can occur. The flues of people who rely on wood-burning stoves or fireplaces to heat their homes through the night are particularly prone to rapid buildup.

“If you’ve had a lot of fires in the past two or three years and you haven’t cleaned your flue in that time, you’re due for a flue fire,” Howe said. “Cleaning your flue will make your house a lot safer.”

The Bend Fire Department responds to about 15 flue fires each winter, Howe said. The La Pine Rural Fire Protection District, which covers a more rural, forested jurisdiction, responds to almost daily flue fires during the beginning and end of winter because that’s when chimneys tend to be dirtiest, said Chief Mike Supkis.

If some smoke already leaks into your home after you light a fire in the fireplace, you may have a partially obstructed flue.

As tempting as it might be to try to clean it by poking around with a broom, leave the job to professionals, fire officials said. A certified cleaner will not only scrub the vent or chimney but also inspect it for any signs of decay that can expose housing materials to extreme temperatures. Around a dozen chimney cleaners serve Central Oregon.

Even if your fireplace or stove pulls a draft, flue cleaning should happen at least once a year, preferably in October or November before the burning season, Howe said. An older fireplace or stove, especially one used as a home’s primary heating source, should be cleaned quarterly or even monthly, Supkis added.

An ounce of prevention

There are several additional ways to prevent a flue fire. Begin with resisting the urge to burn this year’s Christmas tree and instead burn last year’s. Chopped wood takes about a year to season, or thoroughly dry out, Howe said. Don’t put wet logs on a fire hoping they will dry out. That moist smoke causes a quicker buildup of gooey creosote.

Discarded gift wrapping paper may seem like ideal fireplace fodder, but resist the urge to set a large wad on fire. The high heat can send burning paper scraps up the chimney, where it can ignite the built-up creosote, Howe said. A dangerously outdated way of thinking about a flue fire is that it’s an effective way to clean out a chimney, he added.

“The problem is that a flue fire can get as hot as 2,500 degrees,” Howe said, explaining how such a temperature can damage a metal flue and, over time, a brick chimney, depending on how and when it was built. A failing chimney may leak extreme heat into an attic, which can spark materials like insulation, turning a flue fire into a house fire.

A raging inferno

What does a flue fire look like? Sometimes you can hear a roaring sound or feel a vibration in the flue, but it’s just as possible that you could be enjoying your fire and not know what’s raging overhead and out of sight. But your neighbors might notice, Howe said.

“You’ll have fire and a lot of smoke coming out of your chimney,” Howe said. “It’s not getting smoky in the house because the flue fire is pulling air and heat at a great rate.”

A flue fire may be shockingly apparent if your home has a stove with an exposed metal flue.

“I’ve seen metal flues get so hot they turn red,” Howe said. “It’s really hot when it does that. It’s really scary.”

If your flue catches fire, call 911, Howe said. If you have a fireplace, don’t close the damper because the burning logs still need a place to go. Close the glass doors of your fireplace — if it has them — which will restrict air flow to the fire. The same goes for a stove — choke out the air that is feeding the fire in the first place.

Don’t lob water up into the flue. The drastic temperature difference can crack its walls. Also, water that ends up on the roof can make an icy hazard for responding firefighters, Howe said. However, spritzing — not dousing — the burning logs with a spray bottle will create steam that can help extinguish the fire.

Or you can just leave it to the professionals.

“The fire department will get there in 5 minutes and we’ll take care of it,” Howe said. “We won’t make a big mess. It’s not a big emergency to us, even though it looks dramatic. If a homeowner tries to take care of a fire, they’ll either make a big mess or they’ll damage their flue — that will cause a big emergency once they have another fire.”

Supkis agrees that remaining cool is key.

“The first thing to do is to not to panic,” he said. “So long as the fire is still inside the flue.

What we don’t want are recurring flue fires, whose recurring heat may damage the flue, which will create greater problems.”

Another important safety tip, especially for residents in wooded areas, is to make sure flue caps, which are affixed to the top of chimneys, don’t get clogged with creosote.

That’s like leaving a banana in a car’s tailpipe.

“When that happens, the smoke has nowhere else to go but down and back into your house,” Howe said. “And that makes a huge mess.”

You can inspect a flue cap yourself by climbing onto the roof. You can also hire a professional.

Flue caps, which are screen filters that prevent burning debris from floating out, are required in Deschutes County. Caps are especially crucial for residents who live in wooded areas.

Without a flue cap, embers can float out and land on pine needles clogged in gutters, a nearby firewood stack or landscaping materials.

Keeping a 30-foot perimeter around your home that’s free of burnable material is a smart way to prevent a fire due to a chimney spark.

It can also keep your home safe in the event of a wildfire, when “snowstorms” of embers might blow onto your property, Supkis said.

That’s called keeping your home “fire wise,” he added, “or (creating) smart landscaping for living in a fire habitat.”

— Reporter: 541-617-7816, pmadsen@bendbulletin.com