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Why Does Creosote Build Up?

It’s a known fact that burning wood in the fireplace results in a buildup of creosote in the chimney. But why is that? Do some chimneys accumulate creosote faster than others? And is there anything that can be done to reduce the buildup of dangerous creosote in your chimney?

Why does creosote build up in chimneys?

Creosote is a byproduct of incomplete wood combustion. When wood burns, creosote forms and is carried upward by smoke. As the smoke cools within the chimney, creosote-laden condensation forms on the walls of the chimney, where it hardens and can pose a fire hazard. Note, however, that creosote is a result of INCOMPLETE wood combustion. Creosote itself will actually burn up if the fire is burning hotly and efficiently.

Why do some chimneys accumulate creosote faster?

Because creosote does burn up in a hot, efficient fireplace, some chimneys do, in fact, accumulate creosote faster than others. Wood begins to break down chemically at 500 degrees Fahrenheit. Once the temperature of the fire reaches 1,100 degrees, the gases and creosote the result from wood combustion also burst into flame. EPA-rated fireplace inserts, air-tight fireplaces, and woodstoves often generate temperatures in excess of the 1,100 degrees Fahrenheit, meaning those types of appliances will send much less creosote up the chimney than open-hearth fireplaces or older, less efficient fireplace inserts or wood-burning stoves.

In any fireplace, however, the smoke cools as it travels up the chimney. Any smoke that cools below that 1,100 degrees before the creosote burns will leave condensation on the chimney walls. Because the smoke reaches those cooler temperatures before exiting the chimney, some chimney types will accumulate more creosote because of their bends and crooks. Those types include:

  • metal chimneys,
  • chimneys that are located on exterior walls,
  • chimneys that don’t draft efficiently,
  • chimneys that are too large for the fireplace and chimney

What you can do to lessen creosote buildup in your chimney:

Once you know the science behind creosote formation, and that cooler fire temperatures lead to more rapid creosote formation, there are steps you can take to slow the buildup of creosote in your chimney. There are two factors to take into consideration when aiming to reduce creosote formation: You need to make sure that your fires are burning hot and that smoke is exiting your chimney quickly and efficiently. Some things you can do to slow creosote buildup include:

  • Burning dry firewood that has been properly seasoned,
  • Keeping the damper fully opened every time you burn a fire,
  • Maintaining a hot, vigorously burning fire,
  • Monitoring the temperature of your fireplace or chimney to ensure its burning hot enough to ensure creosote combustion,
  • Making sure your chimney flue is properly sized for your fireplace, and
  • Replacing inefficient open-hearth or outdated fireplace inserts with newer efficient EPA-certified models.

Of course, stemming the dangers of creosote buildup in your chimney begins with annual chimney sweepings and inspections. If you’re due to have your chimney swept and inspected, call A to Z Chimney Services to schedule your appointment today!

Have your chimney swept now!

Chimney Sweep Schedule Now Image - Sacramento CA - A to Z ChimneyNovember ushers in the start of the holiday season. That means hectic schedules filled with shopping, family gathering and parties. It also means chillier nights spent gathered around the warm glow of your hearth. If you haven’t had your annual chimney sweeping and inspection yet, your busy holiday schedule could prevent you from enjoying your fireplace. Have your chimney swept now, before your schedule gets in the way, so your fireplace is ready for your holiday gatherings and chilly nights spent at home!

Don’t risk lighting a fire before your chimney has been cleaned and inspected.

Home fires caused by chimneys and fireplaces cause an average of 22,300 home fires each year, resulting in $97 million in damage and 20 deaths, according to statistics from the U.S. Consumer Product Safety Commission. In most cases, chimney fires could have been prevented with a chimney sweeping and inspection.

The sweeping itself removes hazardous materials, such as creosote, animal nests or debris, that can ignite when the fireplace is in use. The inspection can locate weaknesses in the chimney structure or fireplace that could lead to a home fire. That’s why the National Fire Protection Association recommends that chimneys should be swept and inspected annual to lower the risk of a home fire. Ideally, you should have your chimney swept and inspected before you light your first fire of the season.

In addition to dramatically reducing your risk of a chimney or house fire, your annual chimney sweeping and inspection can help protect your family from dangerous carbon monoxide. Blockages within the chimney or malfunctions in your fireplace can cause carbon monoxide to build up within your home, putting your family and your pets at risk for carbon monoxide poisoning. Your chimney sweeping will make sure your chimney is free from obstructions, and during your inspection, your chimney sweep will check to make sure your fireplace or heating stove is functioning properly.

Schedule your chimney sweeping with A to Z Chimney Services today!

Get your chimney ready for the holiday season by scheduling your annual sweeping and inspection with A to Z Chimney Services. When you hire our CSIA-certified chimney sweeps to service your chimney and fireplace, you can trust that you are getting well-trained professionals who will properly care for your chimney and your home.

Every one of our chimney sweepings ends with a ChimScan video chimney inspection, so you can be confident that your chimney is free from debris and free from any structural weaknesses that could put your home at risk. If there is a problem with your chimney, you will be able to see it clearly on the inspection video, and our sweeps will be able to help you find the right strategy for addressing any problems with your fireplace or chimney. And our no-mess guarantee means that you won’t have to worry about cleaning up after our sweeps.

Enjoy your fireplace without worry this holiday season. Call A to Z Chimney Services to schedule your chimney sweeping and inspection today!

Tell Me About Creosote

Don't let creosote build up. Schedule your chimney for an inspection and cleaning.

Don’t let creosote build up. Schedule your chimney for an inspection and cleaning.

If you have a wood-burning fireplace, creosote build-up is something you must always think about as it can be a major cause of chimney fires. With proper chimney maintenance like an annual chimney sweeping and an inspection from A to Z Chimneys, the levels of creosote in your chimney should stay on a manageable level. However, if this important task is ignored, you are risking a chimney fire as creosote is a highly flammable material. We at A to Z Chimneys want to inform you about creosote and its dangers.

What exactly is creosote and how is it formed?

According to the Chimney Safety Institute of America, chimneys that serve wood-burning fireplaces and stoves have the task of expelling all the by-products of combustion, substances produced when wood burns like smoke, gases, water vapor, tar fog, unburned wood particles, and assorted minerals. As these substances exit your fireplace and move through your cooler chimney, condensation happens, and the resulting residue that sticks to the inner walls to your chimney is called creosote.

What does creosote look like?

Varying greatly in appearance, creosote can either be brown or black in color. It can also be flaky and crusty, or drippy, sticky, and tar-like, or shiny and hardened. You can even have every different type of creosote possible in your chimney. No matter what creosote looks like, every type has one thing is common: it is highly-flammable and very dangerous when you have a lot of creosote in your chimney. Highly combustible, it doesn’t take much for a build-up of creosote to cause a chimney fire.

What encourages the buildup in creosote in your chimney?

Certain factors speed up the accumulation of creosote on the flue walls of your chimney: burning unseasoned wood and restricted air supply — both of these cause temperatures in your chimney that are cooler than normal. When you burn unseasoned wood, a lot of energy is used to burn off the water trapped inside of the cells of the wood, and this keeps the smoke temperature cooler than usual. Restricting the air supply by closing the glass doors to your fireplace or not opening the damper wide enough increases the smoke’s “residence time” in your chimney’s flue, making it more likely for creosote to form. Similarly, a wood stove’s air supply can also be limited by closing the damper too soon or too often, which leads to creosote buildup. Another cause of creosote buildup in wood stoves is overloading the firebox with wood.

Do I need to worry about creosote buildup with my gas fireplace?

No, creosote only forms from wood burning, so if you have a gas fireplace, you don’t have to worry about this chimney problem.

How do I prevent an excessive creosote buildup?

According to the Chimney Safety Institute of America, there are certain things you can do to prevent creosote from building up in your chimney: burn only treated firewood, avoid burning fires that are slow and smoldering, be sure your airways in your chimney are not restricted (damper is open and glass doors are also open), and, most importantly, schedule your annual chimney sweep and inspection.

At A to Z Chimney Sweep, we provide chimney sweeps and inspections to find and remove excessive creosote buildups in your chimney to keep you safe from dangerous chimney fires. Contact us today to schedule an appointment for your annual chimney sweeping and inspection.