I am currently installing a stacked washer/dryer in my 2nd story bathroom. The only option for me to vent the dryer is up into the ceiling and down through the soffet. Is there a problem with the dryer vent being vertical until it reaches the ceiling? Since it is a stacked dryer, the vertical distance should only be 2' max (I am not sure whether the duct opening is on the top or bottom of the dryer). Any help on this would be much appreciated. Thank you.

I am currently installing a stacked washer/dryer in my 2nd story bathroom. The only option for me to vent the dryer is up into the ceiling and down through the soffet. Is there a problem with the dryer vent being vertical until it reaches the ceiling? Since it is a stacked dryer, the vertical distance should only be 2' max (I am not sure wether the duct opening is on the top or bottom of the dryer). Any help on this would be much appreciated. Thank you.
I see no problem with the short (2') vertical run but... make sure you do not exceed the total allowable vent length (dyer specific)

Off the top of my head you are generally allowed something like 20 to 25' with a few 90 degree bends.

Keep the vent length as short as possible, minimize the 90's & do not use screws to assemble the vent tube... use aluminum tape (not duct tape)

I have some installs where the aluminum tape is over 20 years old & still fine. If the vent tube is new there might be a light coat of oil on it... remove oil & let dry before taping.


If you have to have a long vent run there are booster fans but they're expensive.


I have an install where the run is ~20' with two 90's... the dryer was taking about two hours to do a load of towels. I fished a nylon rope through the vent & secured a rag ball to it. Cleaned out about the equivalent of two wash cloths worth of lint... no the towels dry in less than an hours.

A clean & properly working vent is essential to good dryer performance.

Cheers
Bob

Bob is absolutely correct on all accounts. Back in the 70's we used 30 feet as the absolute max on dryer venting and subtracting 5 feet for every 90 degree elbow that was used. It's probably still about the same, and the dryer exaust comes out the bottom of the dryer.
And what ever you do, try to use only 4" solid aluminum piping and NOT the flexible tubing if at all possible.