Re: Condensation problem in AC ducts

I would appreciate your comments on this problem...

The air handler + ducts are in an unheated attic [I live in WV]. The AC vents are in the ceiling. Condensation accumulates in the
ducts during the winter from air that leaks into the ducts from the ceiling vents. This moist air condenses in the ducts. The attic ducts consist of a rigid duct that travels the length of the attic with 6" flexible ducts connecting the rigid duct to the
ceiling vents. The rigid duct is covered with 2" insulation. The flexible ducts are insulated.

Question: How to stop the moist air from condensing in the ducts?

Possible solutions????
[1] Add more insulation to the rigid and flexible ducts? Am I correct that this will slow the condensation process, but not prevent the condensation since the ducts will eventually get cold enough to reach
the dew point?
[2] Keep the ducts warm by periodically [say about once per week] running the air handler during the winter for about 30 minutes or so?
The problem - large heat loss due to keeping the return vent uncovered [we open the return vent grill, remove the filter, and place 4" insulation on top of the grill.].
[3] Remove the flexible ducts from the ceiling vents in the fall and reconnect in the spring? I do this now, but this is a real pain and not the preferred solution.
[4] HELP - Anything else????

Just had a central air system like yours installed this past summer. I asked specifically about this problem to the Amana installer. His reply was ...they do NOT insulate the rigid portion of the AC system for this very purpose..but do insulate the flexible ducts. Also, that that is why all the duct work is suspended from ceiling and at an angle, to prevent any place where moisture could accumulate and actually form ice or "puddles", that a slight amount of sweat as you put it is no problem. Finally, and most importantly, some companies do make and insulated cover for your ceiling vents, to prevent any heat loss up into the duct work, and thus less possibility of moisture.

Duct that is insulated sufficiently and the insulation sealed away from moisture both by mastic-sealed joints and well-taped outside coverings will not accumulate moisture. It is just that insufficient insulation is accepted as standard on ducts. You would not insulate a modern home with just two inches of insulation in the walls, or the walls would sweat also. The metal duct can be masticed, taped, and insulated with two-inches of foil-faced foam, masticed and taped, then wrapped with the fiberglass two inches. they would not sweat with that quality of insulation, so the ducts could be left open to the rooms. Cycling a blower for 1/2 hour per day or per week will not stop the condensation. As long as duct is cold enough to collect moisture, it will.