Are Chimney Dampers and Flues the Same Things?

Chimney dampers and flues are different components of the chimney, but they are strongly associated. The damper is a moving part that either allows or prevents an exchange of air and combustion gases into the chimney flue or from the chimney into the home. Anyone who has a masonry chimney really needs to know about dampers and flues, and details follow.

What is a Flue?

A chimney flue is the lining of a masonry chimney. The flue provides the path for combustion gases to travel from the fireplace to the out-of-doors. When it comes to safety, the flue is arguably the most important part of the chimney. Flues provide protection against two kinds of potentially life-threatening conditions, those being pyrolysis and toxic gases.

The Threat of Pyrolysis

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The chimney flue is a wall of protection that prevents combustible materials from being exposed to high temperatures. If even the smallest crack develops in a flue liner, heat can get through to combustible materials such as interior lumber. If the damage in the flue liner goes undetected, combustibles will continue to be exposed to heat. A process of pyrolysis slowly changes the make-up of the combustible materials.

Ultimately, what happens is that the temperature at which the combustible materials will suddenly ignite is greatly lowered. With no warning, a blazing fire can ignite and quickly spread throughout the home as a result of the damaged flue.

Exposure to Toxic Fumes

The combustion gases created by fires contain deadly carbon monoxide. If there is damage to the flue, gases from the fires can leak into the home. The threat of carbon monoxide is particularly frightening because the gas is deadly and it is also:

  • Invisible,
  • Tasteless,
  • Odorless, and
  • Symptomless until it may be too late to escape to safety.

Working carbon monoxide detectors provide the best chance to survive a leak of toxic gases through a damaged chimney flue. Without an alarm to provide a warning, the chances of surviving an unknown carbon monoxide leak can be minimal.

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What is a Damper?

The damper is a metal seal at the bottom of the chimney that is opened and closed in the firebox area of a hearth. The first thing to do when preparing to light a fire is to open the damper. This allows the combustion fumes to go up the chimney instead of in your home. In a masonry chimney, the damper should be fully opened when the fires are burning.

Sometimes a chimney flue is filled with a column of cold air. Opening the damper is not enough to allow air to go up the chimney because the cold air is blocking it. In order to get heat to properly rise up the chimney, light a newspaper torch. The torch is lit and held up to the open damper. After one or maybe two tries, the issue is resolved and the chimney draft will operate the way it is supposed to.

After a fire has gone completely cold, the damper should be closed. If the damper does not seal completely, it cannot fulfill its purpose at this point. A leaky damper is like an open window that pulls your heated air from your home and causes your utility bill to skyrocket. If your damper does not create a good seal, a damper repair or replacement may be needed, and a chimney professional can help.

If you live in or around Alpharetta, GA, Chimney Solutions is the best place to call for chimney services. The condition of chimney flues is usually discovered during chimney inspections. Fire safety experts recommend scheduling annual chimney inspections, and ensuring that the flue is intact is a major reason to follow their advice. Call the CSIA-certified experts at Chimney Solutions at (770) 255-1300 today.

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