How often should you clean your dryer vent?

Short answer

Clean the dryer vent once a year. A large household, or a dryer with a long duct run to the outside, needs it every 6 months. The vent is the duct that runs from the back of the dryer to the flap on the outside wall, and the lint that gets past the dryer's lint screen collects along its whole length. A brush kit on a drill clears it in 30 to 60 minutes, and the kit costs $15 to $40.

Why it matters

Lint is dry, fluffy and made of fibers, which is to say it's tinder. The lint screen catches most of it, but some rides the hot, damp air out through the duct, where it cools, sticks to the walls and dries. Year by year the layer thickens, especially at every bend and at the flap outside. Then one day the dryer's heating element runs hotter than usual, or a spark jumps, and there's fuel along the whole length of the duct. Dryer fires are among the most common home fires, and lint is the usual cause.

Short of a fire, a clogged vent makes the dryer work harder. Damp air can't get out, so clothes take longer to dry, the dryer runs longer, and the bill goes up. The heat that should have left through the duct builds up inside the machine, which wears out the heating element and the motor. A clean vent is cheaper on every count.

When to do it more often

A large household running several loads a day: every 6 months. Lint builds in proportion to loads.
A long duct run, or one with several bends: every 6 months. Each bend is a place lint collects, and a long run gives it more wall to stick to.
A dryer that vents up through the roof rather than out a wall: lean toward every 6 months, since lint has to climb and tends to fall back.
Any time the signs below show up, whatever the calendar says.

What you need

A dryer vent brush kit, with flexible rods that screw together and a round brush on the end
A vacuum with a hose
A screwdriver, for the clamps on the duct
A drill, to spin the brush rods through the duct
Foil tape, to reseal any joints the cleaning loosens

Steps at a glance

Unplug the dryer, or turn off the gas and unplug it if it's a gas dryer, and pull it away from the wall.
Loosen the clamp and pull the duct off the back of the dryer, then vacuum lint out of the dryer's exhaust port.
Go outside, open the vent flap, and pull out the lint packed behind it.
Feed the brush into the duct from the outside, adding rods as it goes, and spin it with the drill while pushing in and pulling back.
Run the brush from the inside end too, and vacuum up everything the brush pushes out.
Reattach the duct to the dryer, seal any loose joints with foil tape, push the dryer back, and plug it in.
Run the dryer empty on air and check that the outside flap opens and air blows out strongly.

You're done when the flap outside swings open on its own while the dryer runs and the air coming out is strong and warm.

Signs it's overdue

Clothes take more than one cycle to dry.
The top of the dryer is hot to the touch while it runs.
A burning smell in the laundry room.
Lint around the outside vent, or a flap that doesn't open when the dryer runs.

DIY or pro

This is a moderate job. The brush kit does the work, and the drill makes it fast. The parts that need some care are disconnecting the duct without crushing it, and dealing with a long or hidden run that the brush can't get all the way through. A flexible foil duct that's crushed or kinked behind the dryer is worth replacing with rigid metal while you're there, since it traps far more lint.

A vent cleaning service charges $100 to $200 and brings stronger tools, including a vacuum that pulls from the outside while brushing from the inside. That's the right choice for a vent that runs up through the roof, a run the brush can't reach the end of, or a vent that's badly packed. If the dryer is gas and you'd rather not handle the gas connection, that's another reason.

Safety

Electricity: unplug the dryer before you pull it out or disconnect the duct. For a gas dryer, also shut the gas valve behind the machine, and don't strain the gas line when you move the dryer. If you smell gas when you reconnect it, shut the valve and call the gas company.

FAQ

How do you know if your dryer vent is clogged?

Clothes take more than one cycle, the dryer gets hot on top, or there's lint around the outside flap. A flap that stays shut while the dryer runs is a clogged vent.

Can I clean a dryer vent myself?

Yes, with a brush kit and a drill. A straight run of duct to the outside is a short job. A long or roof-mounted run is harder, and a service has better tools for it.

How often do dryer fires happen?

Often enough that lint in the vent is one of the leading causes of home fires. A yearly cleaning is the main defense.

Is a foil dryer duct safe?

Flexible foil kinks and catches lint, and a crushed section behind the dryer is a common cause of poor airflow. Rigid or semi-rigid metal duct is the better choice.