Your dryer manufacturer will have specifications for maximum vent line length, including max distances depending on type and size of vent and how many turns.
It is very important that you:
- use rigid rather than flexible line whenever possible
- minimize elbows and turns
- make it as short of a run as you can (never exceed manufacturer's max)
It is not unusual to have a 30' length, but it should be rigid pipe. Check out this chart.
So here I go Answering my own question. I was really hoping to get some objective feedback.
I chose to go out the gable end. Ultimately, of all of the choices, I went with what would be the straightest possible run, even though it added some length.
Basically, here's the thing, for any of us doing a dryer vent run, and we are NOT exceeding the manufacturers length for run, we aren't breaking any code, and while time will tell whether the efficiency is better or worse, I truly suspect the added bend (even just the one if I went soffit) would have been "5 extra feet" and physically forces the air to move directions.
The Gable run basically was 4x5' in the ceiling of the attic and a downward slope with taped joints, so there is one 90 off the highest end which goes DIRECTLY down.
I moved the pipe so it dropped directly into the mud room and didn't touch the garage space at all, thus, the only other 90 is the one that comes off the back of the dryer.
I suspect this will be the easiest run to clean. It only penetrates the ceiling. Other than moving the first column of air (straight up 12') to the 90, it then slants downward at a little more than 1/4" per foot, right to the gable. I used aluminum hobby wire and hung it from the rafters (existing 2x4's) across them gave me a nice spot to work with. I just need to insulate it next.
Indeed the previous flex tubing was clogged, a fire waiting to happen. Makes me wonder where the moisture was going. No water in it, but it sure was full of lint.
Now when it snows I'm confident snow will not block the duct exit on the gable, any condensate that becomes water will still make it outside thank you gravity, and it will be easy to clean out.
next I'll probably buy on of those sensors just to be a perfect reminder of when to clean it out. (time to do some research).
Best Answer
If the dryer is venting in to the attic space, then absolutely this could cause moisture buildup in the attic. You need to get your condo board to address this right now before the problem becomes even more expensive.