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NFT: HVAC Experts: Condensation in Vents?

Bobby Humphrey's Earpad : 11/19/2014 1:14 pm
This morning I get a call from my wife that there is water dripping through the Central Air vent in the kitchen. I had been in that area about three hours earlier and there was nothing. Naturally the concern is that there's a roof leak, but the last time it rained was a couple of days ago and there's no staining or bulging in the ceiling. This is strictly a central air vent; we have baseboard heat.

My father-in-law went by and said that the drip was coming from inside the mouth of HVAC pipe/ductwork itself. The vent is located in the area where my wife cooks, washes dishes with hot water, etc. Could the steam from that been trapped in the HVAC, froze in the cold temperatures, and then melted when the sun started hitting the roof in the morning? Any another explanation?
Could be condensation  
mrt46and2 : 11/19/2014 2:44 pm : link
If the duct is in a cold attic and not insulated well, then the warm humid air from cooking is probably condensing on the inside of the duct, which is cold. If there is a damper on the register, you could try closing it or sealing it with plastic. Otherwise look at your insulation situation on the duct and I would check for mold, you don't want to be breathing that in when you fire up your system in the spring.
Thanks.  
Bobby Humphrey's Earpad : 11/19/2014 3:09 pm : link
I'm sure there's no insulation up there, I can barely get to that section of the attic.
Do you have any snow on your roof?  
MOOPS : 11/19/2014 3:10 pm : link
Could be an ice damn created by freeze/heat cycles, with water backing up under the ice and dripping in under your shingles. If it happens to penetrate above your ductwork, it could easily roll down and drip through your ceiling where your duct is visible.
One possibility.
Does your stove  
pjcas18 : 11/19/2014 3:13 pm : link
have an exhaust?

when I moved into my house the stove exhaust just went into the attic, it wasn't vented.

We had an electrician install a vent.

I don't know if it would cause the condensation like you're seeing, but thought I'd share that.
RE: Do you have any snow on your roof?  
Bobby Humphrey's Earpad : 11/19/2014 3:23 pm : link
In comment 11988870 MOOPS said:
Quote:
Could be an ice damn created by freeze/heat cycles, with water backing up under the ice and dripping in under your shingles. If it happens to penetrate above your ductwork, it could easily roll down and drip through your ceiling where your duct is visible.
One possibility.


No snow, but thanks.
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