How to clean a dryer vent

Clean the lint filter before and after every load, check the venting behind the dryer a few times a year, and clean the full vent run from the dryer to the outside at least once a year. The U.S. Fire Administration lists failure to clean as the leading factor in dryer fires, and the vent duct is where the lint the filter misses ends up. A dryer that has started taking two cycles to dry towels is usually telling you the vent is half closed.

Lint leaves the drum with the moist exhaust air. The filter catches most of it; the rest travels down the duct, sticks to any bend, ridge, or sag, and builds up. Restricted airflow makes the dryer run longer and hotter; in the worst case the lint in the duct or behind the dryer ignites.

How to tell it is time

Other signs: a burning smell during a cycle, the laundry room getting warm and humid, lint around the outside vent hood, or the flap on the hood not opening when the dryer runs.

What you need

• A dryer vent cleaning kit: flexible rods that screw together with a round brush on the end, made to chuck into a drill or turn by hand
• A vacuum with a hose and crevice tool
• A screwdriver or nut driver for the duct clamps
• Foil tape (not duct tape, which dries out and lets go) for reassembly
• A flashlight, gloves, and a dust mask
• A helper for moving the dryer, especially a gas dryer

Steps

1. Unplug an electric dryer. For a gas dryer, turn the gas valve behind the dryer to off before moving it, and do not stretch or kink the gas connector; if the connector is short or stiff, stop and have the cleaning done by a pro.
2. Pull the dryer out far enough to reach the back. Done when: you can see the duct connection and the wall.
3. Disconnect the transition duct at both ends (the dryer and the wall). Look at it. If it is plastic or foil, put it in the trash and replace it with rigid or semi-rigid metal; this is the single change that most reduces the risk.
4. Vacuum the dryer's exhaust port and the lint that has collected behind and under the dryer. The USFA's flyer specifically says to clean the back of the dryer where lint builds up.
5. Clean the wall duct from inside. Attach the brush to one rod, insert it into the wall opening, and push in while turning (clockwise so the rods do not unscrew). Add rods as you go. Work the brush back and forth. Pull it out and vacuum what comes with it. Repeat until the brush comes out clean. Done when: no more lint.
6. Go outside and clean the vent hood. Remove the cover or lift the flap, pull out the lint, nests, and debris, and brush from this end toward the house as far as the rods reach. Make sure the flap moves freely. Do not add a screen; the USFA says screens collect lint and clog the vent.
7. Reconnect the transition duct with clamps and foil tape, with as few bends as the space allows and no sags. A duct that bends four times between the dryer and the wall collects lint at every bend; a straighter route is worth rearranging for.
8. Push the dryer back, keeping the duct from being crushed. Plug it in or turn the gas back on. Run it empty on air fluff for a few minutes and check outside that the flap opens and air is moving strongly. Done when: you can feel a solid stream of air at the hood.

When to stop and call a pro

Call a dryer vent cleaning service or an HVAC company if the duct run is long, goes up through a roof, or has bends you cannot reach; if your brush hits something solid; if the duct is crushed inside the wall; if you find the vent terminates in an attic, a crawlspace, or a wall cavity instead of outdoors (a hazard that needs to be corrected, not cleaned); or if you are not comfortable disconnecting and reconnecting a gas dryer. Any smell of gas: leave, then call the gas utility from outside.

A new-construction home with a dryer far from an exterior wall (a second-floor laundry, a closet in the middle of the house) has a long vent by design and needs the yearly cleaning more than most; and a vent that was never connected to the outside, which does happen, is a builder item to report at once.

What to record

The date, what the transition duct was made of and whether you replaced it, how much lint came out, and how long the run is. If the dryer's cycle time drops noticeably after cleaning, note that too; it is the measure that tells you the interval is right. Set the full clean as a yearly recurring task and "check behind the dryer" as a quarterly one.

Common questions

How often should the dryer vent be cleaned?

The lint filter every load, the area behind the dryer and the first stretch of duct a few times a year, and the full run from dryer to outside at least once a year. A long vent with bends, a household that dries a lot, or a dryer that has started taking longer all call for more often.

Can I use a plastic or foil flex duct behind the dryer?

The U.S. Fire Administration says to replace coiled-wire foil or plastic venting with rigid, non-ribbed metal duct. Plastic is fuel; foil sags and collects lint. If the transition piece behind your dryer is plastic or foil, replacing it is the most useful thing in this guide.

The outside flap does not open when the dryer runs. What does that mean?

The vent is blocked, or the flap is stuck with lint or paint. Clear the hood first. If air still does not push the flap open with the dryer running, the duct is clogged somewhere between the dryer and the hood, and it needs to be cleaned before the dryer is used again.

What to do next

While the appliances are on your mind, the other two that quietly lose efficiency are the refrigerator and the dishwasher: cleaning the refrigerator coils and cleaning the dishwasher filter are each a twenty-minute job.