Why your dryer takes two cycles: clogged vents, fire risk and cost

A dryer that needs two cycles to dry a normal load almost always has a restricted exhaust. The heat and moisture the dryer produces have nowhere to go, so the clothes stay damp and the machine runs twice as long. The usual cause is lint packed into the vent run between the dryer and the outside wall, and the fix is a dryer vent cleaning, which Air Force Shield offers as a $90 add-on to a duct cleaning anywhere in Toronto and the GTA.

Why a blocked vent makes drying slow

A clothes dryer works by blowing heated air through the drum and pushing the moist air out through a duct to the exterior. The lint screen catches most of the fibres, but not all of them. What gets past the screen is carried into the exhaust duct along with the damp air, and some of it sticks to the duct walls, especially at elbows, at joints and anywhere the air slows down.

Over months and years that layer builds. As the duct narrows, less air moves through it, the air inside the drum stays humid, and the dryer's thermostat cycles the heating element on and off more often to keep the drum from overheating. The result is a load that comes out damp at the end of a 60-minute cycle and needs a second run. The dryer is working harder, costing more to run and wearing out its heating element and motor faster than it should.

The fire risk, in the NFPA's own numbers

Lint is dry, fibrous and burns easily. When enough of it collects near the heating element or in a duct that is already hot from restricted airflow, it can ignite. The US National Fire Protection Association publishes an analysis of home dryer fires, and its findings are worth quoting directly.

According to the NFPA's Home Dryer Fires report (June 2020), in 2014 to 2018 US fire departments responded to an estimated average of 13,820 home structure fires per year in which dryers were involved in the ignition. The report states that one-third (32 percent) of those dryer fires were caused by a failure to clean, and that this appears to be mainly lint build-up, since 27 percent of dryer fires started when dust, fibre or lint ignited.

Those are American figures, and we have not found an equivalent published breakdown from the Ontario Office of the Fire Marshal. The mechanism is the same on either side of the border. A dryer that cannot exhaust properly runs hot, and the material collecting inside it is fuel.

Five symptoms of a clogged dryer vent

• Long dry times. The clearest sign. Normal loads that used to dry in one cycle now need two, or you have started selecting a longer or hotter setting without thinking about why.
• A hot dryer top. The outside of the machine, and the laundry room itself, feel noticeably warm after a cycle. Heat that should be leaving through the duct is staying in the dryer.
• Lint around the outside hood. Look at the exterior vent cap. Lint stuck to the louvres, the flapper or the wall around it means the duct is pushing lint out under pressure, and more of it is staying inside.
• A burning or scorched smell. Lint lying against the heating element singes before it ignites. If you smell it during a cycle, stop the dryer and have the vent inspected.
• The flapper stuck closed or open. The exterior flap should lift when the dryer runs and fall closed when it stops. A flap that does not move while the dryer is on means almost no air is reaching it. A flap jammed open by lint lets cold air and pests in.

Any one of these on its own is reason enough to book a cleaning. Two or more together mean the duct is probably badly restricted.

Why basement dryers in older Toronto houses clog faster

Dryer exhaust works best when the run to the outside is short and mostly vertical or straight. In many Toronto houses the laundry is in the basement, often on an interior wall, and the duct has to travel a long horizontal distance under the joists before it reaches an exterior wall and turns up and out. Every metre of horizontal run and every elbow slows the air down, and slow air drops lint.

Older runs also tend to use flexible foil or plastic duct rather than rigid metal. Flexible duct has ridged walls that catch lint, and it sags between supports, creating low points where lint and moisture pool together. If your dryer run looks like that, a cleaning will restore airflow, and replacing the flexible section with smooth metal duct will keep it clearer for longer.

Houses where the dryer is on the second floor, and the duct runs down through a wall and across the basement ceiling, have the same issue with extra vertical distance added. These are the runs where we find the heaviest build-up.

How condo dryer vents are routed

Condo and apartment dryers are different again. In most Toronto high-rises the dryer does not vent straight through an exterior wall. The exhaust pipe behind the dryer runs through the suite to a trap box, a lint collection box built into the wall or ceiling, and from there to a duct that exits on the balcony or into a shared exhaust riser. Some suites have the exhaust hood on the balcony wall and it is accessible from outside. Others have no accessible exterior end at all.

Because the run is long and the trap box fills, condo dryers are a common source of the two-cycle complaint. Our condo duct cleaning includes the dryer vent in the flat fee: we clean the vent from the inside screen and the exhaust pipe behind the dryer leading to the trap box, and if the exterior vent is on your balcony and accessible, we clean that end as well.

What a dryer vent cleaning involves

A proper cleaning deals with the whole path, not just the lint screen. On a typical visit the technician will:

1. Pull the dryer out and disconnect the flexible transition pipe behind it.
2. Clean the dryer base and the lint trap housing, where fibres collect below the screen.
3. Clean the flexible transition pipe, or recommend replacing it if it is crushed, torn or made of plastic.
4. Run compressed-air tools or contact brushes through the exhaust duct from the dryer end toward the exterior, with a vacuum capturing what comes loose.
5. Clear the exterior hood, check that the flapper moves freely and clean lint from the louvres.
6. Reconnect the dryer and run it to confirm strong airflow at the outside.

In a house we do this on the same visit as the duct cleaning. The truck-mounted vacuum is already on site for the furnace ducts, and the dryer vent is one more run to clear. In a condo the same work is done with portable vacuum and compressor equipment brought up to the suite. Full details are on our dryer vent cleaning page.

What it costs

Dryer vent cleaning is a $90 add-on to any house or condo duct cleaning, before HST. Other $90 add-ons are the humidifier, the heat recovery ventilator and a set of three bathroom or laundry exhaust fans, and when you book two add-ons the third is free. For condos the dryer vent is already part of the $399 single-unit and $599 double-unit flat fee, so there is no extra charge. Full pricing for houses by square footage is on the duct cleaning cost page.

Pricing is by home size, not per vent, and the cleaning is covered by our "Love it or don't pay" guarantee.

How often to have it done

Clean the lint screen every load. For the duct itself, once a year is the interval most often given for a household that runs the dryer most days, and sooner if drying times have already stretched. We think that is a sensible rule. A single person doing two loads a week can go longer, and a family with young children, pets or a long basement run should not.

A simple test between cleanings: run the dryer on a normal cycle and go outside to the hood. If you can feel a strong, warm stream of air and the flap is fully open, the run is clear. If the air is weak or the flap barely moves, book a cleaning before the next load.

If your dryer has started taking two cycles, get a quote or call (416) 548-7833. We are open seven days a week, 6:00 AM to midnight, and serve Toronto, Peel, York, Halton, Durham and Simcoe.

Frequently Asked Questions

Can a clogged dryer vent really start a fire?

Yes. The NFPA's Home Dryer Fires report found that 32 percent of US home dryer fires in 2014 to 2018 were caused by a failure to clean, mainly lint build-up. Lint is dry, fibrous fuel sitting next to a heating element.

Is cleaning the lint screen enough?

No. The screen catches most of the lint, but what gets past it collects in the exhaust duct over time. Clean the screen every load and have the duct itself cleaned about once a year if the dryer is in regular use.

How much does dryer vent cleaning cost in Toronto?

At Air Force Shield it is a $90 add-on to a house duct cleaning, before HST. For condos the dryer vent is included in the $399 single-unit or $599 double-unit flat fee.

Do you clean dryer vents in condos?

Yes. We clean from the inside screen and the exhaust pipe behind the dryer to the trap box, and if the exterior vent is on your balcony and accessible, we clean that end too.

How long does a dryer vent cleaning take?

As an add-on it is done during the duct cleaning visit, which is about 1.5 hours for a house and about 45 minutes for a condo. The dryer vent itself is a small part of that time.

Should I replace my foil dryer duct?

If the flexible section behind the dryer is foil or plastic, crushed, or torn, replacing it with smooth metal duct will improve airflow and reduce how quickly lint collects. We will tell you what we find when we pull the dryer out.