Common Causes

• The most common reported location for dryer fires is the venting system, and the second most common location is the lint trap. While your dryer's lint filter catches some of the lint output created by the dryer, the rest is pushed into the vent and duct work system attached to your dryer's exhaust. Lint accumulation reduces airflow, which in turn causes the dryer's working temperature to rise. Eventually, the higher temperature can cause a sort of mechanical failure, or ignite the lint, which is flammable.
  
  

Blockage Symptoms

• John Cranor, a home inspector and member of the American Society of Home Inspectors, cautions that there are several warning signs that indicate your dryer may be operating outside safe temperature ranges and could, therefore, be prone to a fire. If your clothes take longer to dry or are significantly hotter than usual at the end of a cycle, your dryer may have a blockage. Other signs include the outside of your dryer getting very hot or the flaps on the end of the dryer exhaust not opening when the dryer is in operation. If you find moisture stains near exhaust ducts, or the air in your laundry room feels excessively warm or humid or smells burnt, it's a sign that you need to perform some maintenance activities to eliminate a lint blockage in the ventilation system.
  
  

Maintenance and Prevention

• The simplest maintenance is also the most crucial: Clean your lint filter regularly. You should also check and clean out duct work and dryer cabinets on a regular basis. Cranor recommends eliminating conditions that lead to blockage. Make sure your dryer is far enough from the wall to prevent crushing or kinks in the connector between the dryer and the exhaust duct. Replace saggy plastic or vinyl ducts with metal ducts. Metal ducts are the current standard because they create optimal airflow and reduce potential lint buildup. Ducts should be as short and straight as possible, to eliminate airflow resistance and minimize back-pressure. If your duct work must turn, use shallower, multiple turns instead of single sharp ones. Use foil tape to join duct segments. Screws can catch lint and compromise airflow. Silver duct has a limited lifespan and is not durable.
  
  

Myths

• A woman's stocking is not an effective lint trap. Placing a stocking over the dryer exhaust is a fire hazard. Vent buckets filled with water are very ineffective at trapping lint, and the humidity created by them can have a negative impact on your home's air quality.