Clothes dryers should have their vents and vent pipes inspected and cleaned at least annually. Heavily used dryers may require more frequent cleaning.
The accompanying image shows a two-year accumulation of lint removed from a smooth-walled vent pipe connected to a gas dryer in one of our units. The amount of lint removed from this 10-foot length of pipe is substantial.
Ribbed accordion-style flex hoses are even less forgiving, since the ribbed walls catch and accumulate lint deposits even faster than smooth-walled pipe. Common complaints of lint buildup include reduced dryer efficiency (more time needed to dry the clothes). Heat backup in the dryer due to poor venting can also burn out thermal overload fuses in dryers, shutting them down completely.
In some cases, lint accumulations result in house fires.
Whether you do the work yourself, or hire a contractor to clean them for you, dryer vents demand periodic attention to ensure safe, efficient dryer operation.