Had central ac totally replaced 3 years ago. I removed the entire system, ducts and all. The old system was about 20 years old. On Long Island, NY. I have a ranch house, flex ducts, air handler sitting on ceiling joists. Belly in every flex duct but not more than 12 inches lower than exit from "distribution box ?" or the turn into the metal boot that sits on the attic side of the sheetrock ceiling with the vent cover on the living side of sheetrock. When I was removing the old insulated flex ducts, there was as much as a gallon of water in the lowest belly part of the flex duct. This was in the early spring, movable louvers were closed on all the vents. House humidity was low for months thru winter.
I figured the water was from warm house air migrating into the ducts in the cold attic and condensing over months of not using the system. Seemed to be black mold also inside the duct when I cut it open. The new system is behaving the same way. I close the house side damper on all the vents in the fall. The new flex ducts have dripped condensation at times thru the vent thru the winter, this week I was in the attic doing work and when I moved a flex duct it was heavy ,and has to have a half gallon of water in it. Has to be from air migrating into the ducts because of the temperature difference. Guess I'll be ordering all new flex duct, don't want to take the chance of mold in the ducts. Any ideas as to sealing the ceiling vents (aluminum) airtight from the living space? This must be a common but unnoticed problem, once the ac system is turned on the water must dry up and then start to build up again next winter.
Long post but I hope understandable. |