I Clean Houses For A Living. The Lint Trap Is Not The Dryer Vent.

You pull the lint screen out, peel off the gray fuzz, put it back, and feel like you did something.

You did. You did about a third of it.

I own a cleaning company in western new york, which means I have been in a lot of laundry rooms that belong to other people. And the thing I have learned is that almost everybody cleans the lint trap, almost nobody has ever cleaned the duct behind the dryer, and a surprising number of people have no idea there is a duct behind the dryer at all.

The lint you pull off the screen is the lint that got caught. The lint that matters is the lint that got past it.

where the rest of it goes

A lint screen is a coarse filter. It catches most of what comes off your clothes, not all of it. The rest goes where the air goes — into the duct, around the bend, down the run to the wall, and out through the flap on the outside of your house.

Except it does not all make it out. Lint is light and sticky, the air slows at every elbow, and the inside of that duct is warm and slightly damp. So it settles. A little each load, for years.

Then two things happen at once, and they feed each other.

Restricted airflow means the moisture has nowhere to go, so your clothes take two cycles instead of one. And a dryer that cannot exhaust properly runs hotter — it is designed to cycle its heat on a thermostat, and when the air stops moving the thermostat has a harder job. Meanwhile the thing packed into the duct is dry, fluffy, extremely flammable fabric fiber.

The NFPA has looked at this. In their reporting on home fires involving clothes dryers, the leading cause is failure to clean — roughly a third of them. Not a faulty machine. Not a wiring problem. Lint.

I am not trying to frighten anybody. It is an appliance, not a bomb. I am saying the maintenance job nobody does is the one the fire data keeps pointing at, which is an unusual combination and worth twenty minutes of your fall.

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the four signs, in the order you will notice them

• Everything takes two cycles. The single most common one, and the one everybody blames on the dryer getting old.
• The top of the dryer is hot at the end of a load, hotter than it used to be.
• The laundry room is humid, or smells faintly of warm laundry all the time. That moisture was supposed to leave the building.
• The flap outside barely moves. Go out while the dryer is running and look at it. It should be blowing open with warm air you can feel from a foot away. If it is fluttering, or shut, or you can see lint packed around the grille — that is your answer.

That last one is free and takes thirty seconds and I would do it before buying anything.

what actually cleans it

None of this is difficult. It is just awkward, because it happens behind an appliance in a badly lit room.

Unplug it first. If it is a gas dryer and you are not confident about the shutoff and the connection, this is the one place I would tell you to pay somebody. Gas is not a learn-as-you-go thing.

1. Do the slot the screen lives in. There is a felt-like layer of lint down inside that housing that the screen never touches. A long flexible lint brush gets down there and drags it up — I have not used this exact brush, but the category is about two dollars of bent wire and bristle and any 24-inch-plus one does the job. Vacuum after.
2. Pull the dryer out and disconnect the duct. Two feet is enough. Expect a shock at what falls out.
3. Brush the run out. A vent brush with a vacuum attachment handles the first few feet and the machine’s own outlet, which is where a lot of it sits. For a longer run through a wall or up through a ceiling you want the 30-foot flexible rod kit that screws onto a drill — feed it in from outside, run the drill forward only, and let the brush walk itself down. Both of these are what I would buy; I am recommending the design, not reporting on a decade of personal use.
4. Clean the outside flap and the grille around it. Birds nest in these. So do dryer lint and, in this part of the country, several years of leaves.
5. Look at the duct itself before you put it back. This is the part of the job that actually matters and I have put it fifth because nobody reads the fifth item, so: if what is behind your dryer is white vinyl or thin foil accordion hose, replace it.

the hose is the whole thing

Ribbed plastic and foil accordion duct is cheap, sold everywhere, and terrible. Every ridge is a shelf for lint. It crushes flat when you push the dryer back against the wall, which is exactly what everybody does. And the flexible plastic kind is not rated for this and will not stop a fire the way metal will.

What you want is semi-rigid aluminum transition duct — it holds its shape, it does not collapse, and the inside is smooth. It costs about the same as the bad one. This is the one I would buy: a plain 4-inch by 8-foot length, cut down to the shortest run that will reach, with as few bends as you can manage. A short straight duct beats a long clever one every time.

Two things people get wrong when they put it back together:

• Do not use screws inside the duct. Sheet metal screws poke into the airflow and catch lint like a comb. Clamps on the outside, always.
• Do not use duct tape. Genuinely — duct tape is not for ducts. The adhesive bakes out with heat and it lets go in a couple of years. Use foil tape rated UL 181, which is the thing the rating exists for. I have not used this specific roll and I do not need to have; the spec printed on it is the whole point, and any tape carrying UL 181A-P or 181B-FX is the right tape.

And while I am here: the indoor venting kits, the bucket of water you are supposed to vent into when you have no outside wall. I would skip them. They are not allowed for gas dryers at all, and for an electric one you are choosing to pump a gallon of water per load into the air of your own house. I spend my working life dealing with what that moisture does to bathrooms. Do not do it to your basement on purpose.

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while you are already back there

It is mid-September, the furnace is about to come on, and you are going to shut this house up for seven months. Two other things live in the same twenty minutes.

The washer next to it holds water in places you cannot see — the gasket, the dispenser drawer, the drain filter behind the little door at the bottom. That is where the towel smell comes from, and a washer cleaning tablet on an empty hot cycle deals with the drum part of it. And the furnace filter is the single cheapest thing you can change before heating season, because every bit of air in the house is about to go through it repeatedly. These two are category picks rather than lifelong favorites — check the filter size printed on the edge of your old one before you order, because 16x25x1 is only one of about fifteen sizes and the listing is per size.

Twice a year for the lint trap housing, once a year for the duct, more if you have a long run or a dog. That is the whole maintenance schedule.

The most boring possible way to spend a Saturday morning, and the payoff is that your clothes dry in one cycle and nothing catches fire. I have made my peace with boring.

Some of the product links in this post are affiliate links, which means I get a small commission if you buy through them, at no extra cost to you. I have flagged in the text where I am recommending a category rather than something I have personally worn out.