What a dryer vent does and why it matters
A dryer works by heating air, passing it through the drum, and pushing the warm, damp air out of the house through a vent duct. If that path is partly blocked, moist air and heat stay in the machine. Clothes dry slowly, the dryer runs hotter than it should, and lint can collect in places where it does not belong.
Lint is flammable, and a restricted vent is widely recognized as a contributor to dryer fires. For that reason, vent problems are worth taking seriously even when the only symptom you notice is slow drying.
Symptoms of a clogged or restricted vent
Any one of these can point to a vent problem. Several together make it more likely.
- Clothes take longer than usual to dry. Needing a second cycle for ordinary loads is the most common early sign.
- The dryer or the laundry room feels unusually hot or humid during a cycle.
- Clothes are hot but still damp at the end of a cycle.
- A burning or musty smell while the dryer runs. If you notice a burning smell, see what to do about a dryer burning smell.
- Lint around or behind the dryer, or lint pushing out around the duct connection.
- Weak airflow at the outside vent hood, or a hood flap that barely opens.
- The dryer shutting off mid-cycle because a safety thermostat tripped. This is covered in more detail in our article on dryer overheating.
- A vent or error light on some models (see below).
Common vent problems and causes
- Lint buildup. Some lint always gets past the filter and settles in the duct, especially at bends and long runs.
- A crushed or kinked transition duct. The short flexible duct behind the dryer is easy to flatten when the dryer is pushed against the wall.
- Unsuitable duct material. Thin plastic or vinyl ducting and ribbed foil ducting can sag, trap lint and are not recommended by most dryer manufacturers. Rigid or semi-rigid metal duct is generally preferred. Check your dryer manual and local building code.
- A blocked exterior hood. Bird nests, other debris, or a damper that sticks closed can stop air from leaving.
- A disconnected or damaged duct. Joints can come apart, sending warm, lint-laden air into a wall, attic or crawlspace. This is a hidden problem that needs prompt attention.
- A long run with many bends. Longer and more twisted ducts restrict airflow more. Your manual gives the maximum length for your model.
- A clogged lint filter or filter residue. The filter is not part of the duct, but a coated or blocked filter reduces airflow in the same way. See how to improve dryer performance for how to clean it properly.
What the “Check Vent” light means
Some dryers have a light or message that warns of restricted airflow. On a GE dryer, a “Check Vent” light generally means the dryer has detected poor airflow and wants you to inspect the filter and vent. Other brands use different wording or codes. Check the manual for your specific model.
If the light comes on, a reasonable first response is to:
- Stop the dryer and let it cool.
- Clean the lint filter, and wash it if it has a film.
- Check the transition duct for kinks and the outside hood for blockage.
- Run a short test cycle.
If the light keeps returning, the duct itself likely needs cleaning or repair. For brand-specific codes, see our Kenmore dryer codes article for an example of how codes vary between makers.
How to check your vent airflow
Before you start, switch the dryer off. If you will move the dryer, be careful with the cord and, on a gas dryer, do not strain or pull on the gas line.
- Check the hood outside. Run the dryer on an air-only or low-heat setting. Warm air should push the hood flap open firmly. Weak or no airflow suggests a blockage somewhere along the duct.
- Look at the transition duct. Pull the dryer out a little, if you can do so safely, and check for crushing, kinks or disconnected joints.
- Inspect the hood for obstructions such as nests or leaves, and remove what you can reach safely.
- Check the lint filter slot. A flashlight and a vacuum crevice tool let you see and remove lint that has fallen below the filter.
How to clean the vent safely
Homeowners can reasonably handle short, accessible, straight runs. A typical approach:
- Turn off the dryer and unplug it. For a gas dryer, do not disconnect the gas line yourself. If the dryer has to be moved far enough to strain the gas connection, stop and get a professional.
- Detach the duct from the back of the dryer by loosening the clamp.
- Vacuum lint from the duct and the dryer outlet with a hose attachment.
- Use a dryer vent brush kit designed for the purpose, working from the inside or outside as the instructions describe, and keep the brush moving in the correct direction.
- Clean the exterior hood and make sure the flap opens and closes freely.
- Reconnect with secure clamps. Avoid using screws that stick into the duct, as they can catch lint. Use foil tape or clamps as your manual or local code suggests.
- Push the dryer back carefully without crushing the duct, then run an air-only cycle and check airflow at the hood again.
When to call a professional
Cleaning a vent is not the right DIY job in every home. Call a qualified dryer vent or appliance technician if:
- The duct is long, runs through walls, ceilings, crawlspaces or the roof, or you cannot see or reach the whole run.
- You smell burning, see scorch marks, or the dryer has shut off repeatedly because of heat. Stop using the dryer until it has been inspected.
- You have a gas dryer and anything about the gas connection, the burner, or a gas smell concerns you. If you smell gas, leave the home and contact your gas utility or emergency number from outside. Do not operate switches or the dryer.
- The vent has damage, a disconnected joint, or unsuitable material that needs replacing.
- You still have poor drying after cleaning the filter, hose and hood.
A restricted vent can also contribute to exhaust gases entering a home from a gas dryer, so a blocked vent on a gas dryer is not something to put off. Our gas vs electric dryer article explains why venting matters even more for gas models.
How often to clean the vent
Many manufacturers and fire-safety sources suggest having the full duct cleaned at least once a year. Households that dry large loads often, have pets, or have a long duct run may need it more often. Clean the lint filter after every load, and look at the transition duct and the exterior hood a few times a year.
Preventing vent problems
- Empty the lint filter before or after every load.
- Wash the filter occasionally if water does not drain through the mesh or you see a film.
- Use metal duct rather than plastic or foil accordion duct, as your manual allows.
- Keep the duct as short and straight as practical.
- Leave a little space between the dryer and the wall so the duct is not crushed.
- Keep the exterior hood clear of plants, snow and debris.
- Do not overload the dryer.
FAQ
Why isn’t my dryer drying my clothes?
A restricted vent is one of the most common causes, but not the only one. Other causes include a clogged filter, an overloaded drum, or a failed heating part. If the dryer is running but not producing much heat, that points to a component issue; if it is hot but clothes stay damp, think airflow first. See how to improve dryer performance for the quick checks.
How often should you have your dryer vent blown out?
At least once a year is a common recommendation. Heavy use, a long run or pets in the household may call for more frequent cleaning.
Can a clogged vent make a dryer overheat?
Yes. Trapped heat can trip safety thermostats and stress parts. See our dryer overheating article for causes and next steps.