- Venting a dryer through the roof requires that the appliance's exhaust fan fight the downward force of gravity while carrying air filled with lint and moisture through a long run of tubing. Current industry standards recommend the use of rigid aluminum or galvanized steel ducts no longer than 25 feet in length. Each 45-degree bend decreases the recommended length by 2.5 feet and each 90-degree bend warrants a 5-foot reduction in length.
- If improper venting material is used, lint becomes trapped in the ducts, making the long runs heavier to support. Dryer vents installed through the roof must be properly supported with metal clamps at each bend and seam or an annoying banging of moisture- and lint-laden pipes against the roof framing structure and roofing material may occur. Not only is the banging a nuisance, but it may also signal that your vents have clogged up and require cleaning to avoid a house fire.
- Never use PVC pipe, plastic or foil spiral flexible ducts to vent your dryer. Doing so may void your dryer warranty should maintenance issues occur. Examine your roof vent to ensure that the exhaust is being vented through a screenless opening that measures a full 4 inches in diameter and that the damper on the end of the pipe opens fully. You should correct sharp turns, humps and sagging vents to eliminate the turbulence that can result in banging noises in your attic.
- Pay attention not only to banging noises but to other warning signs as well. If your dryer is taking an inordinately long time to dry an average load of clothes, or your clothes are excessively hot at the end of a drying cycle, a clogged vent or damper may be the problem. Professional duct cleaning services may be required to reach long runs of roof-vented ductwork and clear obstructions that may otherwise lead to a dangerous dryer fire.
Recommended Standards
Venting Issues
Corrective Measures
Warning Signs
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