A friend of mine called me about a strange situation he has with some ductwork. The homeowner noticed all of the insulation on his ductwork in the crawlspace was wet. My friend says that the original tape and insulation job was poor, so he just assumed that this was the cause of the wet insulation. He then proceeded to remove all existing insulation, sealed all joints with mastic tape, and re-insulated all pipe with two inches of foil-back wrap.
He called me yesterday and said that when he checked on the system again, that there was a light film of condensation forming on the outside of the duct on most of the system. I told him to make sure that he did not have a "lazy air" situation, which he does not, (there is 1550cfm of pipe on a four ton system) there is good velocity out of all the registers. He said there is a moisture barrier on the ground, and that the dirt under that was dry everywhere. Foundation vents were open however.
This is a house in Little Rock, AR. We have had an enormous amount of rain in the last thirteen months, and it is quite humid here, but he says the ground is dry under the house.
Any idea why this would be happening? No lazy air problem, no moisture problem (seemingly) under the house.