Preventing Fires
I've experienced a house fire in the past, so I have a passion for keeping people from going through such an experience.
One major cause of house fires is the simple dryer vent. According to a 2009 report released by the National Fire Protection Agency:
- 17,700 reported U.S. non-confined or confined home structure fires involving clothes dryers or washing machines resulted in 15 civilian deaths, 360 civilian injuries and $194 million in direct property damage in 2006.
- Clothes dryers accounted for 92% of the fires; washing machines 4%, and washer and dryer combinations accounted for 3%.
- The leading cause of home clothes dryer and washer fires was failure to clean (29%), followed by unclassified mechanical failure or malfunction (24%). Thirteen percent were caused by some type of electrical failure or short circuit.
That's a lot of death, property damage and money, especially since these fires are easy to prevent.
How Dryers Work... And Fail
As clothing tumbles dry, water vapors get forced out of the house through dryer vent. Most clothing dryers have a gas burner or are operated by electricity. Both types of dryers push warm air against the tumbling clothes. This tumbling and hot air circulation evaporates the water that is left in the load of laundry.
Lint is one of the byproducts of the tumble drying process, and it happens to be highly flammable.
As the dryer duct pipe becomes obstructed and filled with lint, drying time increases and causes the dryer to overheat and waste energy because the dryer can't eliminate the heated water vapor effectively.
The heat energy is then stuck in the machine, where it accumulates. If the dryer overheats, a mechanical failure can trigger sparks... which can cause lint trapped in the dryer vent to burst into flames. Fires generally originate within the dryer but spread by escaping through the ventilation duct, incinerating trapped lint, and following its path into the building wall.
Lint isn't the only culprit when it comes to obstruction. Bird or rodent nests in the termination and crushed or kinked flex hose are other notorious problems.
Unfortunately, the dryer vents in many older houses terminate in crawlspaces or attics. This will deposit moisture in these areas, which will encourage the growth of mold, wood decay, or other building material problems.
Some quick tips to avoid dryer fires:
- Use ridged dryer ventilation pipe and stay away from the flexible dryer venting pipes
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Vents should be as straight as possible and cannot be longer than 25 feet - according to the International Residential Code
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Any 90-degree turns in the vent reduce this 25-foot number by 5 feet (due to restricted airflow) - according to the International Residential Code
- Limit the number of elbow connections to not more then two (in 20 foot run)
- Vent the dryer to the exterior and not under a deck, porch, window well or interior space
- Do not install a screen at the dryer vent exhaust end... it just traps lint
As A Side Note:
Dryer lint is great for helping campfire-challenged parents light a campfire. I like making a "candle" of dryer lint by mixing it with wax in an old egg container. Put the material in, let it harden, and in a few minutes you'll have a week's worth of campfire starters.
You can find out more about dryer vent safety at www.HouseSleuth.com.
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