soggy outlet pipe for dryer?

darsunt

I was cleaning out a 19 foot long length of duct for dryer that hasn't been cleaned out in years. A 9 feet section of duct that was lower than the outlet is absolutely soggy, the lint there was like a swamp.
Is this common, moisture collecting in the outlet duct of a dryer? I couldn't find any source of outside moisture besides the dryer, and I know a lot of moisture goes through that duct. Also what should I use to patch around the wall around the duct when I replace it? I don't think the duct gets too hot, would spackling be good enough?

gregzoll

19 feet is way too long for a dryer vent. Isn't there any way to make the run shorter? As for getting any moisture out, it needs to always slope towards the outside.

darsunt

This is one of those 'designer' townhouse apartments. It is a very beautiful place, but sometimes the looks take precedence over practicality. No there is no way to shorten the vent.
I assume you are saying my intuition is right, that the dryer air flows through too much pipe and the moisture gets precipitated out. I intend to slope the ducts so that everything is higher than the outlet. So at least the moisture will drip out and not collect in the middle of the pipes.
Again, will spackling paste be safe to seal the vent against the walls? I don't think the dryer vents gets that hot.

DexterII

Spackle should be fine, although, due to the temperature changes that it is subject to, I would use regular drywall mud, which you can buy premixed at most hardware stores and home centers, and which will allow for more expansion and contraction. As mentioned, way too long of a run, but you have already responded to that, so you'll have to make the best of it. I assume that you are using rigid metal vent, if not, change to that, use an absolute minimum of elbows, and use foil duct tape on all of your joints, to ensure that you create the best flow possible.

Gary in WA

Use a lightweight Spackle which won't crack or shrink like drywall mud (hence the 3 coats). Use caulking or even a rope caulk next to the pipe.
The run is still under the required 25’ maximum, depending on how many elbows involved. Some areas this changes to 35’ max., depending on which year code and which type of code. Most Codes refer to the manufacturer’s lengths for the brand dryer: http://www.appliance411.com/faq/dryer-vent-length.shtml
The duct termination hood is very important; Type “A” is the best.

http://docs.google.com/viewer?a=v&q=...up65cYgFwMvULw

http://www.ashireporter.org/articles...es.aspx?id=161

Be safe, Gary

__________________

darsunt

The vent runs through a 12' long closet under the entrance stairs. The designers wanted the closet to be usable, so the duct is run along the inside walls to maximise space. Which means at least 3 additional 90 degree turns. I suppose I could nail the closet door shut and run the vent straight across the closet space (sigh). At least I will slope the vent and insulate it. And use foil duct tape.