Dryer Vent Fire Safety Checklist: Ten Checks in Order

A clothes dryer pushes hot, lint-laden air through a duct for an hour at a time, often several times a week. When that duct narrows with lint, the dryer runs hotter, takes longer, and the lint itself becomes fuel. The U.S. Fire Administration lists failure to clean dryers as the leading cause of home clothes dryer fires. Most of what prevents them is free and takes a few minutes.

The checks below are in the order you'd naturally do them, starting inside the drum and working outward to the vent hood on the outside wall.

Ten checks, inside to outside

1. Clean the lint screen every load. Before or after each load, not once in a while. If you can't see through the mesh even after removing the lint, dryer sheets may have left a film; wash it with warm soapy water, rinse and let it dry fully.
2. Vacuum the lint screen housing. With the screen out, use a narrow crevice tool down the slot. Lint that gets past the screen settles here.
3. Read the label on what you're drying. Items stained with cooking oil, gasoline, paint thinner or similar should not go in a dryer. Oil-soaked rags and towels can heat and ignite even after washing.
4. Look at the duct behind the dryer. It should be rigid or semi-rigid metal. Plastic or foil accordion duct crushes easily and holds lint in every ridge; replace it.
5. Check the duct route. Shorter and straighter is better. Each bend adds resistance. Make sure the dryer isn't pushed back so far that the duct is crushed against the wall.
6. Disconnect and clean the duct at least once a year, more often if you dry a lot of towels or bedding. A dryer vent brush kit reaches most runs; long runs through an attic or across a garage ceiling may need a professional cleaning.
7. Feel the airflow outside. With the dryer on high heat, go to the exterior vent. You should feel strong, warm airflow.
8. Watch the vent hood flap. It should open when the dryer runs and close when it stops. The USFA advises checking that the outdoor vent covering opens when the dryer is operating. Wasp nests, bird nests and sticky salt-crusted hinges near the coast all keep flaps shut.
9. Remove any screen on the hood. Screens on dryer exhaust hoods catch lint and clog. Use a hood with a flap or louvers instead.
10. Clear the floor around the dryer. Lint, boxes and stored items around the base of the dryer can catch a spark or block airflow to the motor.

Signs it's time to stop and look closer

A dryer usually tells you when the vent is in trouble. Watch for these:

• A normal load now needs two cycles.
• The top of the dryer or the clothes come out unusually hot.
• The laundry area feels humid or smells musty while the dryer runs.
• You smell something hot or burning.
• Lint is collecting around the outside vent hood.

Any burning smell means stop the dryer, unplug it or switch off the breaker, and don't use it until the cause is found. If you see smoke or flames, get out and call 911.

Gas dryers need one more look

A gas dryer exhausts combustion gases along with lint, so a blocked vent can push carbon monoxide back into the room or garage. Make sure there's a working CO alarm nearby, and never let a gas dryer vent into the garage or attic. Our gas appliance CO checklist covers alarms and warning signs. If you smell gas, leave and call SDG&E or 911 from outside.

Habits that reduce risk

• Don't run the dryer when you leave the house or go to bed. The NFPA's safety tips advise not leaving a dryer running if you leave home. Time-of-use savings at midnight aren't worth an unattended dryer.
• Don't overload the drum. Clothes need room to tumble and air needs room to move.
• Use the moisture-sensing or auto-dry setting if your dryer has one, so it shuts off when the load is dry instead of running a fixed time.

When the vent is clean but the problem isn't

If you've cleaned the full vent run and drying times are still long, the cause is likely in the dryer: a failing heating element or gas valve coil, a cycling thermostat, a worn blower wheel, or a thermal fuse that has blown. A blown thermal fuse is often a symptom of a past vent restriction, so replacing it without fixing the airflow just sets up the next failure. Our dryer technicians test airflow and the heating circuit together. For common dryer brands such as Whirlpool, most heating parts are readily available.

Sources

• U.S. Fire Administration: Clothes Dryer Fire Safety (PDF)
• NFPA: Clothes Dryer and Washing Machine Safety (PDF)

Put a reminder in your calendar for the yearly duct cleaning. Pair it with a date you won't forget, like the first week of the school year.