Condensation Problems

seeyou

Got a warranty call on a cedar shingle roof we did about a year ago. 210 year old house, original split sheathing, 6-8" of cellulose blown over mostly original plaster, 3 brick thick walls, gable roof, continuous venting at eaves. There was no venting at the ridge and the ridge is "combed".

Air handler for the heat pump is in the attic of the 2 story section. The house is only occupied sporadically, but the heating/cooling is maintained with no setback. Ductwork is metal with fiberglass wrap. Best I could gather is that the HVAC was installed in a major renovation in '94. Didn't look at what brand it is.

Here's the problem: Every inch of the f/g insulation on the ducts (supply & return) is pretty much saturated and dripping. All supply registers are covered with mold. The living space was plenty cool, but felt humid to me. The pan under the air handler had not had a drop of water in it since we replaced the roof - it was still dusty from the re-roof.

Our weather has been in the mid to high 90's and fairly humid for the last 5-6 weeks which is a little hotter than normal for that time of year. We typically don't get that 'til now.

I no longer have a dog in the fight now that it's been determined that the massive plaster damage is not the result of a roof leak, but I'm curious. What's causing this massive condensation?

yuri

Leaks in the return duct joints sucking in excessive amount of humid air from the attic. They should all be coated in red durodyne duct sealant/mastic or silver duct tape is one possibility. Sounds like the air is cool in the house but humid which corresponds with that theory.

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seeyou

All of the duct work is wrapped with FG so I didn't observe whether the joints are tapped or not. But this system has been in place for 16 years and this problem has just occurred in the last 6 wks or so. Thanks.

yuri

Things change, one or more may have got loose from vibration. May even have a flex canvas connector at the air handler buried under the insulation and now it dried up and broke.

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