Lint buildup in a dryer vent is a leading cause of house fires, and a clogged vent also makes the dryer work harder and run longer. Cleaning it is a quick job with a big safety payoff.
Warning signs
Clothes taking longer than one cycle to dry, the dryer or laundry room feeling unusually hot, a burning smell, or the lint trap filling fast all point to a restricted vent that needs cleaning.
Clean the whole run
Unplug the dryer (and for gas, take care with the gas line), disconnect the vent hose, and clean the lint trap, the hose, and the duct all the way to the exterior vent hood with a vent brush or vacuum. The exterior flap should move freely and not be blocked.
How often
Clean the vent at least once a year, more with heavy use or a long duct run. Clean the lint trap every load. Avoid long, kinked plastic vent hoses — rigid or semi-rigid metal duct is safer and traps less lint.