Re: dryer duct wrong?
IMHO you should limit vertical runs in dryer vents to as short as possible and take the most direct rout to the outside. The air flow from a dryer is not high pressure and has problems expelling lint. In a tall vertical run the lint flutters around in the air flow and then drops when the dryer is turned off eventually causing a clog at the bottom of the run this then restricts air flow and drying. And as MLBFS said you should not install a booster blower in the line for the reasons mentioned.
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