Forgetting to Open the Flue Damper for a Fire in the Fireplace Causes Smoke to Backup into Houses on Hi-Lusi Ave in Mt Prospect and Downing Rd in Buffalo Grove

Probably a lot more people are using their fireplaces for a little extra heat today. That means a greater chance that a number of people might forget to open their fireplace flue damper. Firefighters in Mount Prospect were called to an address on Hi-Lusi Avenue and firefighters in Buffalo Grove were called to an address on Downing Road. Both homes filled with smoke, most likely caused by forgetting to fully open the flue damper. Firefighters at both locations help ventilate the home, but there was no fire in either home.

The damper should always be fully open before starting a fire in the fireplace and when the fireplace is in use. Close the damper only when the fireplace is not burning a fire.

Some people think they might keep more heat in the house if they close the damper flue partially, but blocking the passage of heat exhaust and smoke through the flue and chimney will result in smoke backing up into the home.

If the flue is entirely closed, a frightening amount of smoke and even flames can jump into the living space of the home, instead of rising up the chimney. That usually results in a call to the fire department for help.

A partially closed flue damper can also cause less than ideal heat conditions upward inside the chimney. A relatively cooler chimney can cause more creosote to build up inside the chimney. Over several fireplace uses, excessive creosote can eventually start on fire and extend heat into the frame of the house. If there is fair warning, a neighbor might see flames shooting out of the chimney, before the attic or roof starts on fire. However, if the ignition occurs inside the attic, a full-blown attic fire and roof fire could cause a very serious house fire.

The flue damper should be kept open until all embers are finished burning to prevent smoke from escaping into the home. When the fireplace is not in use, the damper should always be closed to prevent heat from escaping out of the house, and to prevent animals from entering the house. An open damper is like an open window, allowing large amounts of heat from the home to escape. A closed fireplace damper when there’s no fire in the fireplace will result in money saved on heating expense in cold weather and air conditioning expense in hot weather.

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The National Fire Protection Association Standard 211 says, “Chimneys, fireplaces, and vents shall be inspected at least once a year for soundness, freedom from deposits, and correct clearances. Cleaning, maintenance, and repairs shall be done if necessary.” This is the national safety standard and is the correct way to approach the problem. It takes into account the fact that even if you don’t use your chimney much, animals may build nests in the flue or there may be other types of deterioration that could make the chimney unsafe to use. The Chimney Safety Institute of America recommends that open masonry fireplaces should be swept at 1/8″ of sooty buildup, and sooner if there is any glaze present in the system. This is considered to be enough fuel buildup to cause a chimney fire capable of damaging the chimney or spreading to the home. Factory-built fireplaces should be swept when any appreciable buildup occurs. The logic is that the deposit is quite acidic and can shorten the life of the fireplace.

— Chimney Safety Institute of America

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Homeowners should always make sure there chimney is not obstructed. Sometimes forgetting to open the flue might not be the problem. There could animal nests or damage caused by animals that cause an obstruction or other problem with the chimney. Or the build up of creosote could obstruct the chimney. The National Fire Protection Association recommends that chimneys should be inspected once per year.


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