Quick answer
A dryer that takes 2+ hours per load has a clogged vent line — 90% of the time. Lint accumulates in the vent hose and duct, blocking airflow. Clothes stay wet because moisture can't escape. This is a serious fire hazard — clogged dryer vents cause thousands of home fires yearly. Clean the vent from both ends: lint trap first, then the full duct with a vent brush kit ($15).
Key facts
| Common causes | Clogged vent duct; Lint trap clogged or restricted; Exterior vent hood blocked; Failed heating element |
|---|---|
| DIY difficulty | Easy |
| Time to fix | 45 min |
| Parts cost | $0–$30 parts |
| Tools needed | Vent brush kit, screwdriver |
| When to call a pro | Long vent runs · rooftop terminations · heating element replacement |
What's happening
Dryers work by heating air and blowing it through tumbling clothes, then venting the moisture-laden air outside. Lint builds up throughout: the lint trap (obvious), the duct behind the dryer (accumulates over months), and the exterior vent hood (birds nest there). When airflow is restricted, drying time doubles or triples, the dryer runs hot, and lint accumulation itself can ignite. Long dryer times are the #1 sign of impending fire risk.
Common causes (ranked by frequency)
- Clogged vent duct 70% of cases
Lint accumulates over 6–12 months. Duct becomes narrowed to a straw. Airflow drops dramatically. Clean once per year minimum.
- Lint trap clogged or restricted 15%
Obvious lint trap loading = clean after every load. But lint also builds up inside the trap housing itself over months — use a vacuum crevice tool.
- Exterior vent hood blocked 10%
Bird nests, leaves, or a failed flap prevent exhaust. Check outside — is air flowing when dryer runs?
- Failed heating element 3%
Electric dryers only. Element burned out, so air doesn't heat. Clothes tumble in room-temp air for hours. $30–$80 part but requires disassembly.
- Failed thermostat or thermal fuse 2%
Cycle thermostat or high-limit thermal fuse failed. Element gets no power. Diagnostic requires multimeter testing.
How to diagnose
- Check if the dryer produces heat. Run empty for 10 minutes; feel the interior with the door open (careful — hot). No heat = element or thermostat failure.
- Check exterior vent hood while dryer runs. Strong airflow = duct is clear. Weak or no airflow = duct is clogged.
- Check lint trap and its housing. Pull out lint after every load; vacuum the trap housing quarterly.
- If exterior airflow is weak, proceed to vent cleaning.
The fixes
Fix #1 — Clean the dryer vent Do this annually
The single most impactful and safety-relevant dryer maintenance task. A $15 brush kit does 20 feet of vent.
Tools
- Dryer vent brush kit ($15) — flexible rods + brush head
- Cordless drill (some kits connect to drill for spinning action)
- Vacuum with hose
Materials
- Unplug dryer (electric) or turn off gas + power (gas dryer).
- Pull dryer away from wall enough to access the vent connection.
- Disconnect the flexible transition hose from the back of the dryer and from the wall duct. Clean this hose thoroughly (usually the worst clog).
- Assemble the vent brush kit. Insert into the wall duct.
- Push the brush all the way through the duct to the exterior. Push and pull to loosen lint.
- Go outside and clear lint from the exterior vent hood. Also check for bird nests or debris.
- Vacuum thoroughly at both ends of the duct.
- Reconnect transition hose. Push dryer back. Restore power.
Fix #2 — Clean lint trap housing
Even with good habits, lint builds up inside the trap housing over months.
Tools
- Vacuum with crevice tool
- Small flashlight
Materials
- Pull lint trap out. Clean off any lint on the mesh.
- Wash the trap in warm soapy water occasionally to remove fabric softener residue that blocks airflow.
- Use a vacuum crevice tool to reach deep into the trap housing. A flashlight helps locate compacted lint.
- Reinsert the clean trap.
Prevention
Clean the lint trap after every load. Clean the vent duct annually (or more often for heavy-use households). Never use a plastic or vinyl transition hose (fire risk) — use rigid metal or semi-rigid aluminum. Keep the dryer at least a foot from the wall to prevent transition hose crushing. Look up your exterior vent hood location and check it monthly for bird nests.
When to call a pro
When to stop and call a pro
- Vent cleaning didn't shorten dry times — could be heating element or thermostat.
- Long duct run (25+ feet) or rooftop termination — professional cleaning is more thorough.
- You suspect element failure and are uncomfortable disassembling the dryer — pro repair.
- Gas dryer with any issue — never work on gas connections yourself.
Professional dryer vent cleaning: $100–$200 for standard runs. Heating element replacement: $150–$300. New dryer: $400–$1,200.
Cost estimate
Cost estimate
Frequently asked questions
Very. The US Fire Administration reports thousands of dryer fires annually. Long dry times are the leading warning sign. Annual vent cleaning is the single most effective prevention.
Yes — commonly used approach. Blast air from the exterior vent hood back through the duct. Lint blows out the interior end. Follow with the brush kit for thorough cleaning.
No — plastic and vinyl vent hoses are fire hazards and violate code in most jurisdictions. Replace with rigid metal or semi-rigid aluminum immediately.
Different fix. No heat at all = heating element or thermostat failure. See circuit issues also — electric dryers use two circuits (240V) and if one leg is dead, the element won't heat but the motor still runs.