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Asbestos in Chimneys, Furnaces, and Wood Stoves

Asbestos is found in a lot of places in homes and other buildings that were constructed before about 1980. Before this time, asbestos was used in numerous home construction materials because it is a cheap and readily available mineral that resists heat and fire and that adds strength. If you live in an older home, be aware of the risks of being exposed to asbestos, which include being put at risk for developing mesothelioma.

Because of its fireproofing and eat resistant properties, asbestos was heavily used in home heating. Chimney flues, furnaces, and wood-burning stoves were all made with asbestos. Originally used to make homes safer, the materials in your home heating equipment could actually pose a risk. If disturbed, fibers of asbestos may get into the air where they can be inhaled. If you think you may have asbestos, a certified professional can inspect and abate it.

wood stove

Transite Asbestos in Chimneys

Many chimney flues, the pipes that exhaust gases from fireplaces, were lined with a material called transite. This was a brand of asbestos-containing cement material created by Johns Manville. Transite was originally a brand name, but the word became a common term for any similar material. Originally, transite was made with cement mixed with anywhere from 10 to 50 percent asbestos. Asbestos adds strength to materials as well as fire and heat resistance. Asbestos in transite was phased out by 1980.

Homes built before 1980 are likely to contain transite with asbestos, most often in chimney flues. The material was used to line most flues in chimneys in both commercial buildings and residential homes. The purpose of the flue lining is to resist fire and keep heat from escaping. Chimney flues were not the only flues that used transite with asbestos for this protective lining. Any venting flue, connected to water heaters, furnaces, and other appliances, may contain asbestos in older homes.

Asbestos is no longer used in chimney and other venting flues, but it may still exist in those found in older homes. This is dangerous because any renovation or construction work done on the chimney and flue can expose and send asbestos fibers into the air. Even when there is no renovation work going on, the asbestos in older flues can harm residents of a home. The lining material of the flue may deteriorate over time, causing blockages that in turn cause exhaust gases along with asbestos fibers to vent back into the home.

Furnaces and Asbestos Materials

Furnaces are another potential source of asbestos in older home heating systems, and it is not just the venting flue that may contain this material. A variety of types of material containing asbestos were used to insulate furnaces and protect the surrounding walls from heat and the dangers of a fire. These materials include millboard, cement sheet, transite materials, asbestos paper, and asbestos tape.

Gaskets used in furnaces also contained asbestos prior to 1980. Gaskets are rings that connect and join two materials to prevent leaks. Furnace gaskets used asbestos to keep heat from leaking. The doors of furnaces were often also lined with asbestos materials to keep heat in. Vents and ducts leading to and from furnaces may also have been insulated with asbestos.

Asbestos materials in furnaces can be dangerous today because, over time, the heat from the furnace can cause asbestos to become friable. To be friable means that it can be easily crumbled, which can cause fibers to become airborne. Friable asbestos is very dangerous. Older furnaces and duct elements that contain asbestos should be removed by a trained asbestos abatement professional.

Wood-Burning Stoves

Another source of asbestos in the heating systems of older homes is in a wood-burning stove. In addition to the ducts connected to it and the flue used to vent gases, asbestos may be found in components of the stove itself, as well as in insulating material around it. As with a furnace, a stove may have millboard, cement sheet, or asbestos paper and tape around it for insulating and fireproofing.

Older stoves may also have asbestos in the door gaskets. Wood-burning stoves that have cooktop surfaces may contain asbestos in the pads and trivets that sit on top. As with furnaces, asbestos-containing wood stoves should be inspected and abated by a trained asbestos professional. The heat of the stove can cause insulating asbestos to become friable.

Identifying Asbestos in Heating Systems

Determining whether or not you have asbestos materials, like transite, in your chimney flue, furnace, or wood stove, is a task best left to trained professionals. Every state has licensing and training requirements for asbestos professionals who know how to identify and abate this dangerous mineral. For the lay person, identifying asbestos is not easy. It is also very dangerous to try to poke around in materials that may contain asbestos without knowing how to properly protect yourself.

Abating Asbestos

Finding asbestos in your heating systems does not necessarily mean that your family has been put in danger. Asbestos that is well contained and that has not become friable poses no risk to people in the home. However, if you have a professional inspect your home and he finds friable asbestos, you will need to take steps to have it abated.

This could mean having it removed, but not necessarily. Whether or not it makes the most sense to remove the asbestos will depend on the type of asbestos and the condition it is in. Your professional can tell you if removing is the best option. The alternative is to contain the asbestos to keep it from becoming friable. If this is the option you choose, make sure that you have it inspected regularly to ensure that the asbestos material is still in good shape and is not damaged, deteriorating, or friable.

It can be worrying to think that your home may contain asbestos, especially in and around the elements that heat your home and vent gases. With the right professionals inspecting and abating these asbestos materials you should not have to worry about being exposed. If you aren’t sure if your home heating components contain asbestos, have it checked out by a licensed professional, especially if you are planning any renovations or repairs. Having the inspection done first is crucial and could mean preventing you and your family from being exposed to harmful asbestos fibers.

Page edited by Dave Foster

Dave has been a mesothelioma Patient Advocate for over 10 years. He consistently attends all major national and international mesothelioma meetings. In doing so, he is able to stay on top of the latest treatments, clinical trials, and research results. He also personally meets with mesothelioma patients and their families and connects them with the best medical specialists and legal representatives available.

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