Where Dryer Vents Break Down
| Problem | What it causes | Repair |
|---|---|---|
| Hose crushed behind the dryer | Restricted airflow, long drying times | Replace with a listed transition duct; pull the dryer out a little |
| Joint separated inside a wall or ceiling | Lint and moist air inside the building | Open access, reconnect with metal duct, seal with metal tape |
| Outdoor flap stuck or broken | Air can't leave; pests can enter | Replace the hood with a working backdraft damper |
| Screen over the outdoor opening | Lint clogs the mesh | Replace with a hood that has no screen |
| Nest in the vent | Blocked exhaust | See bird nest and lint removal |
The Hose Behind the Dryer Has Rules Too
Virginia's residential code calls the connector between the dryer and the wall a transition duct. It has to be listed and labeled to UL 2158A, run no longer than 8 feet, and never pass through or hide inside a wall, floor or ceiling. Check the label on yours. An unlabeled plastic or vinyl hose doesn't meet the rule.
Replacing a Crushed Dryer Vent Hose
Unplug the Dryer
For a gas dryer, also turn off its gas valve before moving it, and don't strain the gas connector.
Pull the Dryer Out
Give yourself room to reach both connections.
Remove the Old Hose
Loosen the clamps and vacuum lint from the dryer outlet and the wall duct.
Fit a Listed Transition Duct
Use the shortest length that reaches, clamped at both ends.
Push Back Without Crushing
Leave space behind the dryer, then run a cycle and feel for strong airflow at the outdoor hood.
Airflow still weak? The problem sits deeper in the line; book a dryer vent inspection.
Do Plumbers Replace Dryer Vents?
Some do, usually as part of moving a laundry room. Dryer vent work more often goes to dryer vent specialists, HVAC contractors or appliance installers, who carry the brushes, cameras and airflow meters to test the result. Whoever does it, ask for the finished vent to meet Section M1502 of the Virginia Residential Code.
Long Runs and Booster Fans
The code caps the exhaust duct at 35 feet, minus an allowance for every elbow. Longer runs, common in townhomes that vent through the roof, can't be fixed by adding an ordinary booster fan; the code prohibits them in dryer exhaust ducts. A dryer exhaust duct power ventilator listed to UL 705 is the approved option. Clean the run first, as described on the dryer vent cleaning page.