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Dryer vent trouble

My dryer pipe to the roof is causing damage to my ceiling due to condensation on the pipe. I have had four repair/roof specialist here, and none of them would concede that the problem was due to the dryer pipe. I was constantly told it was a leak in the roof. It has not rained for about 2 months, but I have done tons of laundry and tah dah, leaking ceiling! What can I do to fix this, especially since everyone I call will not fix it! Thank you for your time.

Re: Dryer vent trouble

I would have to agree with you the dryer venting is definitely a contributor ...... if not the source ...... for your issue.

Let's start at the beginning .... the dryer.

The reason heat is produced by the dryer ....... warm/hot air has the ability to absorb and carry large amount of moisture vapor.

When you put moist laundry into the dryer heat is produced warming the air inside which allows the moisture in the clothes to be absorbed by that heated air.

The dryer draws out that warm moisture laden air by the exhaust fan inside. This is where the duct is attached exhausting this moisture laden air outdoors.

The problem is cold air doesn't have the ability to hold as much moisture vapor as warm air.
As this warm moist air from the dryer is cooled quickly the moisture in that air will actually be released as water droplets .... in short .... condensation.

So ... if you have cooler temperatures inside the attic ..... that run of ducting inside the attic will be considerably cooler than the run from the dryer to the ceiling.

Compounding the problem is since that ducting will be vertical that condensation will run down and drip onto your ceiling.

Even though there are lint traps at the dryer a certain amount of lint will still be present in the exhausting. If you end up with condensation forming inside the duct this lint has a greater chance of accumulating inside the ducting eventually causing restrictions because of the build up.

Another thing is to ensure the ducting up in the attic isn't simply disconnected or leaking into the attic.
If so you would end up with warm moist air filling the attic and will condense.

It's unknown what type of ducting exists whether it's rigid metal , the inexpensive white plastic flex or insulated flex ducting.

The better method would be having rigid metal ducting all the way with the portion in the attic covered and sealed with an insulated duct wrap.

Personally I would never recommend running the dryer exhaust through a roof .... rather through a side wall ...... especially if you live in an area that has cool or cold seasons.

Also , the more penetrations in the roof the more chance of leaks and I like to keep the run as short as possible.

Hopefully this makes sense and helps. :)

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