I am writing to you in hopes that your experience can assist my family with a moisture problem. Our home tends to have an above-average humidity level. In the past, our air conditioning ducts would fill with water during the winter months, when we were not using the central air. Once the ducts got too full, water would drip from the air conditioning vents in the ceiling. My husband now disconnects the ducts from the vents when the fall months arrive. He then blocks the vents with insulation so that heat is not lost into the attic. Also, he wraps the return filter with plastic.
Our system is only about six years old and we have already replaced all the ductwork due to the water buildup. Because of allergy problems, the return that was installed is all metal rather than the standard construction materials. Even with the return filter wrapped in plastic, there is so much condensation forming within the return that it is causing our ceiling to become wet around the return.