Duct Work Soaking Wet

Old 07-23-13, 05:19 PM
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Join Date: Jul 2013
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Duct Work Soaking Wet

I have a 3.5 ton heat pump in the basement, it is a Gibson split system. One side is rigid duct and I insulated it with R6, this side does not condensate anymore. My basement is unconditioned.

The other side was 12" uninsulated flex. The flex is about 8' in length. It comes off the back of the unit and goes up into the wall and connects to 12" round rigid duct that runs vertical to my 2nd story. The flex was always getting wet and dripping all over the floor so I replaced it with insulated flex and covered the hole in the wall with insulation too. Now, the hard pipe up in the wall is condensating and all of the water is running down into the flex and pooling. I remove the flex from the unit and dump the water into a bucket, probably about a 1/2 gallon every day.

All dampers are wide open.

I run a dehumidifer.

No water is getting into the unit. The drain does drip into my french drain, I plan to install a condensating pump and pump it out of the basement to alleviate as much moisture as possible.

Any ideas?
Old 07-23-13, 07:03 PM
Join Date: Oct 2008
Location: New England
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Measure your RH in the basement to know where you are. Be sure to note the temperature at the same location.

I suspect your duct system is not well sealed and is processing warm moist air since the water is accumulating on the inside of the ducts. It is difficult when ducts are insulated, but aoo seams should be sealed with mastic or foil tape (never duct tape).

I'll let the pros weigh in on the rest.


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