Dryer Vent into Attic causing condensation


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Old 01-25-06, 07:52 AM
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Dryer Vent into Attic causing condensation

I have a gas dryer on the 2nd floor of my house. It vents up the wall into the attic and out the roof.

On semi cold days (30+ degrees), I have watched water drip from all the elbows/joints in the vent pipe leading to where it goes out of the roof.

For a short term solution I wrapped and ductaped towels around the joints, so the dripping water wont cause any more stains on my ceiling below.

What are my options?
Can I cut the hard vent pipe and replace it with the flexible so there are no more joints?
Can I insulate the current vent pipe with something, so the heat exchange from the vent to the cold air in the attic reduces the condensation inside the pipe?


Note: The vent pipe is only warm to the touch when the dryer is running and water drips. It's not hot and there is no condensation on the outside of the pipe. It only builds up on the inside and forces it to drip at the joints..
 
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Old 01-25-06, 07:56 AM
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That duct should of been wrapped with insulastion in the first place. You can get them at home centers, and wrap it over the exposed pipe.

The warm most air is condesating onto the cold metal pipe, so that's why you are getting water.

before you wrap it, it may not be a bad ideal to take it apart, and give a good cleaning inside. and stay with the metal, it provide the best air flow.
 
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Old 01-25-06, 08:18 AM
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That's great information. Thank you.

I have never seen insulation that covers a 4" metal duct at Home Depot.

What does it look like? is it metal or paper backed and you tape the seem closed?
 
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Old 01-25-06, 09:58 AM
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It may vary from store to store. We have the one you just cut and wrap around.

two types are fiberglass, and other is kinda a thin foil like wrap.
 
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Old 01-25-06, 05:07 PM
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Your HVAC dealer can provide you with a sleeve that will go over the pipe that has insulation and a vapor barrier.
 
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Old 01-25-06, 07:31 PM
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4in PVC is the best way to go!
 
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Old 01-26-06, 04:59 AM
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Originally Posted by jayhitek
That's great information. Thank you.

I have never seen insulation that covers a 4" metal duct at Home Depot.

What does it look like? is it metal or paper backed and you tape the seem closed?
It's like a sock...insulation complete with vapour barrier.
 
 

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