Metal Chimneys
Consumer Product Safety Commission
Metal Chimneys:
Safety Alert
CPSC Document #5047
The Consumer Product Safety Commission is again issuing a special safety alert concerning chimneys used with woodburning stoves and fireplaces. This alert is particularly aimed at consumers who have metal factory-built chimneys, although the Commission is aware of house fires associated with both masonry and metal factory-built chimneys.
Thousands of house fires each year are associated with metal factory-built chimneys connected to wood and coal burning stoves. The CSPC urgently warns consumers to be aware of the potential fire hazard associated with these chimneys.
Now that the nation has entered the 1983/1984 heating season, the Commission strongly urges you, if you have a stove or fireplace connected to a metal chimney, to check for any damage that may have occurred in the past heating season. Look for signs of structural failure, such as deformation, cracks, or holes. If it is difficult to examine the chimney, a local chimney repairman, chimney "sweep", or dealer can help. Have any damage repaired NOW.
Most fires in metal factory- built chimneys occur because of improper installation, use or maintenance. The Commission staff has identified the following common causes:
- Improper chimney installation causing ignition of nearby wood framing.
- Structural damage to the chimney caused by burning creosote (a black tar-like substance which builds up inside the chimney).
- Chimney corrosion resulting in wood framing being exposed to excessive temperatures.
- Buckling and collapsing of the inner liner of the chimney. (This can result from too hot a fire, especially in high-efficiency stoves and in fireplace inserts, or from a creosote fire.)
Many serious fires also occur in masonry chimneys, usually from improper installation or when the tile inner liner and the surrounding brick or block structure crack and separate. Such cracks may be caused by the ignition of creosote. Smoke and heat can then escape and ignite material near the chimney.
Even when the heating appliance is properly installed, people with both metal and masonry chimney systems should frequently check the chimney for creosote deposits, soot build-up or physical damage. This involves only a simple visual examination, but it should be done as often as twice a month during heavy use. If you see heavy creosote build-up, suspect a problem, or have had a chimney fire, a qualified chimney repairman or chimney "sweep" should perform a complete safety inspection. They can arrange for any necessary repairs or creosote removal, which must be done before the heating appliance is used again.
The Commission advises owners of these chimneys to:
- Be sure that the chimney and stove pipe were installed correctly in accordance with the manufacturers' recommendations and local building codes. If there is any doubt, a building inspector or fireman can determine whether the system is properly installed.
- Have the chimney checked routinely by a chimney "sweep" at least once a year, and more frequently if a stove is heavily used (for example, if it's used as a primary heat source for the home).
- Always operate your appliance within the manufacturers' recommended temperature limits. Too low a temperature increases creosote build-up and too high a temperature may lead to a fire. Chimney temperature monitors are available and should be used.
If you have had a fire or other safety problem with your chimney, please provide this information to the Commission by calling the Commission's toll-free Hotline 800-638-CPSC.
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