When you dry clothes, the moisture doesn’t all evaporate in the dryer drum; it needs to escape. That’s why there’s a vent in the back (or sometimes side) of the dryer connected to a duct that leads to a vent on an outside wall or on the roof. In a gas dryer, this also vents the combustion gases (carbon monoxide and other yucky stuff). But along with the moisture, lint from your clothes also ends up in there. The lint filter catches most of it, but some escapes and ends up in the space around the dryer drum or eventually in the duct. Because people often forget about cleaning this duct (or the type or configuration encourages lint buildup), lint collects there and can become a fire hazard.
To start a fire, you need three things: 1) something flammable (dryer lint is very flammable), 2) heat (dryers can generate enough heat to raise the temperature of dryer lint to its ignition point), and 3) oxygen (dryers use air). If you don’t clean out the dryer vent or regularly clean the lint filter, you could create the perfect storm that ignites a fire in your dryer or exhaust duct.
Note: There are some types of dryers that are ventless (condensing or heat pump dryers), but they’re not very common in the US due to their higher price, smaller capacity, and longer drying times. However, in some situations (e.g., if there is no access to a vent to the outside), it makes sense. If your dryer doesn’t have a vent, check the owner’s manual for instructions and maintenance.
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How to Prevent a Dryer Fire:
1. Clean the Lint Filter
Make sure you clean the lint filter after every load of clothes. This will not only help prevent the duct from filling up with lint but will also help your clothes dry faster.
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2. Replace Unsafe Ducts
Most dryers have a 4-inch vent on the back or side of the dryer. This connects to an exterior wall or roof vent via a duct. Check behind your dryer for the duct and note the material and type. If your duct is a plastic or foil accordion style, it should be replaced with a rigid metal duct. Accordion-style ducts are not recommended because they can sag, leading to lint buildup at low points and trapping lint in their ridges. A rigid metal duct is the safer option.
Make sure you clean the lint filter after every load of clothes. This will not only help prevent the duct from filling up with lint but will also help your clothes dry faster.
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2. Replace Unsafe Ducts
Most dryers have a 4-inch vent on the back or side of the dryer. This connects to an exterior wall or roof vent via a duct. Check behind your dryer for the duct and note the material and type. If your duct is a plastic or foil accordion style, it should be replaced with a rigid metal duct. Accordion-style ducts are not recommended because they can sag, leading to lint buildup at low points and trapping lint in their ridges. A rigid metal duct is the safer option.
Also, the distance from the dryer to the outside vent shouldn’t exceed 35 feet, with reductions in that maximum distance for each bend in the duct—2.5 feet for a 45-degree angle and 5 feet for a 90-degree angle.
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3. Clean the Dryer Duct Annually
Cleaning the duct can be done from the inside or outside. It’s often easiest to do from the outside, but if the vent terminates on the roof, inside might be better. However, you do want to make sure the exterior vent is clear (i.e., no bird nests). There are brush kits available to clean the length of the duct, or some use a vacuum along with a brush. Many exterior vents have flaps that open when the dryer is pushing air through, but close when the dryer is off to prevent birds and other critters from entering. If the duct hasn’t been cleaned for a while, you might find some surprising stuff will come out. When you’re done, make sure to check that all ductwork is still well-connected.
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Cleaning the duct can be done from the inside or outside. It’s often easiest to do from the outside, but if the vent terminates on the roof, inside might be better. However, you do want to make sure the exterior vent is clear (i.e., no bird nests). There are brush kits available to clean the length of the duct, or some use a vacuum along with a brush. Many exterior vents have flaps that open when the dryer is pushing air through, but close when the dryer is off to prevent birds and other critters from entering. If the duct hasn’t been cleaned for a while, you might find some surprising stuff will come out. When you’re done, make sure to check that all ductwork is still well-connected.
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4. Handle Chemical Stains with Care
Clothes stained with gas, cooking oil, cleaning agents, or other flammable chemicals or substances need special care. It’s recommended to wash stained clothing more than once to minimize volatile chemicals, then hang to dry. If you must use a dryer, use the lowest heat setting and a drying cycle that concludes with a cool-down period.
Clothes stained with gas, cooking oil, cleaning agents, or other flammable chemicals or substances need special care. It’s recommended to wash stained clothing more than once to minimize volatile chemicals, then hang to dry. If you must use a dryer, use the lowest heat setting and a drying cycle that concludes with a cool-down period.
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In the event that a fire does start, call 911. Try to turn off the dryer and keep the dryer door closed to limit its oxygen supply.