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Old 01-11-2011, 04:36 PM   #1
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condensation forming in duct

Ok, here's my situation. We used to have a down-draft swamp cooler for our

cooler. About 18 months ago, we installed a new furnace and A/C unit. The

swamp cooler was removed and the duct was capped. It probably sticks out

of the roof about a foot or so. During the original home construction, there

was no return installed on the top floor. When we put the A/C unit in, we

installed a return into the side of the swamp cooler duct in the attic and ran

it down through the chase to the furnace.

With the very cold weather we are currently having, there is condensation

forming on the inside of the duct cap. I have tried putting sheet insulation

in the duct and sealing it with tape to prevent warm air from getting up there

but not having any luck.

Water is dripping out of the return grate onto the carpet.

I would appreciate any help or ideas on this



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Old 01-11-2011, 05:06 PM   #2
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Spray it with 3M expanding foam sealer used for around doors/windows. Makes a airtight hermetic seal and is impervious to moisture. Won't get wet and rot. Available at HDepot.


"Cut it twice and it is still too short".
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