Just how long can I run flexible dryer vent exhaust duct/hose?

Great question! The professional recommendation: 35 ft. or less. For each 45 degree bend in the duct/vent exhaust hose, you should subtract 2.5 ft from the max allowed length. For each 90 degree bend, you should subtract 5 ft. from the max allowed length. A longer exhaust hose leads to more lint buildup, less effective drying, more wear and tear on your dryer, and more chances for kinking or obstruction of the exhaust. The U.S. Fire Administration (USFA) and National Fire Protection Association (NFPA) estimates that 1500 house fires are initiated each year by clogged or kinked dryer exhaust systems. So, keep them short and clean my friends (kind of like your fingernails)!