What is the maximum duct length for venting the dryer?

The maximum duct length depends on the type of vent hood and the number of elbows used. For example, with a standard vent hood and no elbows, the maximum length is 55 feet of 4-inch diameter rigid metal duct. The chart on page 14 shows specific maximum lengths, and you should deduct 6 feet for each additional elbow. Do not exceed the maximum length for your installation. (Page 14)