Laundry dryer maintenance is often overlooked by home owners and property managers. The lint generated by drying clothes passes through the lint screen and into the exhaust system. Even if the lint screen is cleaned before every use, it only traps approximately 75%. Eventually the dryer exhaust system fills with lint (including house dust and organic particles). The lint compacts over time greatly reducing air flow, increasing energy and cost to run the machine, decreasing the overall life of the machine, and raising the risk of over heating and fire. Dryer exhaust fires now surpass creosote (chimney) fires in frequency on a national level.
We recommend installing a lint alarm on your dryer vent to let you know when it is time for a cleaning. Every machine is different and collect buildup differently. For gas heated dryers, this is especially recommended. In 1998, the most recent study available, the U.S. Consumer Product Safety Commission reported in 1996, dryer-related fires resulted in 20 deaths, 320 injuries and over $84 million in property damage. In 1997, there were 16,700 fires, 30 deaths and 430 injuries associated with laundry dryers. By 2001 they estimated there would be over 24,000 laundry dryer fires each year, amounting to $96,000,000.00 in estimated property damage.
According to the CPSC, in most of the cases, the culprit was lint in the machine's heating element, sparking and fueling a fire. Lack of maintenance is the leading cause of these fires. Lint is the leading ignition material. Not surprisingly some fire departments and insurance companies now require dryer vents be inspected and cleaned regularly.
Improper installation of the exhaust system may also create a hazard. This can cause lint buildup inside the dryer itself, seriously compromising the motor and heating unit, greatly increasing the possibility of a fire. Improper air flow is often caused by the improper use of venting material. Underwriters Laboratories standards 560 and 2158 for clothes dryers specifies all dryers require metal dryer venting. This means no vinyl or plastic dryer vent hoses. Also pay special attention to foil dryer venting hoses which can become kinked if installed improperly or collapse over time. As your dryer motor overheats trying to compensate for reduced air flow or lint clogging the motor itself, the high temperature limit safety switch of the dryer has to cycle on and off to control the heater. Most high temperature limit switches were not designed to cycle on and off continuously, which can cause them to fail.
Increasing heat made by the dryer during cycles due to high temperature limit switch failure can cause damage to clothes as well as greatly limit the life of the dryer itself. With gas dryers there is also the concern of carbon monoxide (CO) poisoning. Since lint and flue gases use the same exhaust system, a blocked exhaust system can cause CO fumes (colorless and odorless) to back up into the home. Low-level CO poisoning mimics flu symptoms (without the fever) including headache, weakness, nausea, disorientation and deep fatigue. At higher levels occupants fall asleep, lapse into a coma and die.
A properly installed and maintained all metal dryer exhaust system will ensure airflow resulting in minimal chance of overheating and fire, lower energy use, lower operating costs, and greatly expanding the life and efficiency of the dryer. In addition, when clothes are given the proper amount of air, they dry quicker and are subject to less tumbling. This means less wear on your clothes as well. It is recommended that dryer vents (exhaust systems) be cleaned at least once a year. Dryer vent cleaning is a cost-effective service that should be a part of every home owner's and property management's maintenance program.