AC register condensation: Not enough ridge for adequate ridge ventilation?
I’m living in the Houston area (zone 2) and noticed water leaking from some AC registers yesterday. The home is 9 years old, 300 sq ft.
The flexible ductwork is insulated.
The register boots are insulated, and the insulation has a lot of mold. (pic attached)
There is significant water in the attic on the blown in insulation around the duct boots: not damp, really wet.
I do not think the register boots are leaking, but I guess they could have small leaks.
Morning humidity is currently around 92%, according to NOAA. Attic humidity was 60% at 8AM today, when outdoor humidity was around 90. (I don’t have extremely accurate measurement tools, just a cheap $15 portable unit ).
My suspicion is the root problem is with inadequate attic ventilation. Attic in the original 3000 sq foot house is unconditioned, blown in fiberglass. There are continuous soffit vents (looks like pegboard, I think it is a Hardie product) around the permitter of the house, but due to the roof design (pic attached), there is one main 10′ ridge vent and secondary 8′ and 4′ ridge vents. I estimated about 400 sq in of roof ridge vent, and think I need probably 3 times that amount.
I would like your help to
(1) confirm that my problem is poor attic ventilation, and then
(2) find need a solution.
My understanding is I would need a dozen or more turbine vents to add 1000 sq inches of ventilation. Also I understand that mixing powered roof vents with ridge vents is problematic. I don’t really have room to put 10 turbine vents at the peak of the roof, which is only about 10′ wide, so…
maybe a couple solar powered roof vents would be practical in this particular situation.
Another note, we recently added 2000 sq feet to the main house. There is very little communication between the two unconditioned attics, basically just an 18″ * 72″ cutout in the old roof to allow walking between attics. The new addition has about 50-60′ of ridge vent.
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