How to Vent a Clothes Dryer
Question: We recently purchased our first home, and I’m having trouble with my dryer. It worked fine before the move, but now I have to run it two to three times to get the clothes dry. I asked the movers if something had been damaged in the move, but they told me to call a repairman. I read your article on electrical appliances being damaged by the wiring in the home. Could that be the problem?
Answer: During the drying process, the moisture from the clothes dryer is carried through a vent pipe to the outside of the home. The shorter the vent pipe, the more efficient the drying process.
Most manufacturers recommend a maximum length of vent pipe of 25 feet, not including the elbows found in most installations. When the vent pipe has to make a 90-degree turn to pass through the floor, wall or ceiling, that turn is equal in restriction to a 5-foot section of vent pipe, so the overall length should be shortened to 20 feet.
Here are other things to check for:
- The lint trap should be clean, and there should be no lint buildup inside the vent pipe. If there’s no buildup and the dryer has to be run more than once to get clothes dry, the problem is usually a vent pipe that is too long or one that has too many turns and bends before exiting the home.
- Vent pipes should be free of kinks, loose or damaged pipes, pipes that are separated at connecting joints (which dumps all the moisture to the home's interior), lint buildup that’s a fire hazard, and other blockages, such as a bird’s nest in the outside vent opening.
- There should be a movable or protected cover on the outside of the home that is not blocked by vegetation or stored items. If the cover is damaged, it should be replaced. If screws have been used to connect sections of vent pipe, the screws need to be removed to keep the interior of the vent pipe smooth and lint-free.
- Sections of vent pipe should be connected with pipe clamps and metallic tape. If your home has a flexible foil or plastic vent pipe, replace it with an approved metal vent pipe. Plastic and most foil-type vent hoses are not approved for the heat generated by a clothes dryer.
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.)