I had a new Carrier Infinity system installed last week in Northern Virginia. So far everything is running splendidly except for one problem--the supply duct in the finished basement just past the coil is sweating profusely. The temperature in the basement is 63 with 60% humidity while the rest of the house is at 76 with 40-45 percent humidity. Outside it has been 88-90 and very humid.
Neither supply register in the basement is open, though there is an open return. I've got the supplies closed because it is so cold anyway. I've got two proposed solutions:
1) Open the supplies. This may bring in dryer air that will not condense on the ducts, though I expect the basement would get even colder.
2) Seal the ducts. I assume the basement is cold because there is duct leakage even though no register is open. If the ducts are sealed, the basement won't be so cold and the ducts won't sweat. My previous system didn't do this even though it was the same size, which makes me think it may not be just duct leakage.
I've got a 3-ton system, and the airflow has mostly been at 1050 cfm. Would it help to change from "Comfort" to "Efficiency" to increase the airflow? Would this result in a smaller temperature drop and less condensation?