Just finished reading the University of Minnesota Extension about moisture in basements, but still have questions.
Background; I'm the original owner of a house built in 1988 in PA. The builder hacks left numerous leaks in the supply and return ducts which I sealed. They used duct board which I now know is a poor choice.
After sealing I noticed a stale musty air in the "unfinished" basement. I remedied this by opening a small 3"x6" opening in the supply duct in the basement. This seemed to work well except the humidity continues to be somewhat of a problem although not as great.
I had Radon remediation done which included a 24x7 fan drawing from two vents placed into the slab.
I just had an Infinity 16 heat pump and oil furnace installed which works exceptionally well. The installer insists I close the 3"x6" "vent" in the supply duct.
I don't want to do this because of my previous problem (stale musty air). The metal duct work just installed going from the system to the duct board is sweating heavily. They will come back to wrap the metal.
My question; what down side is there to leaving the 3"x6" opening in the supply duct? Will it be worse than having stale musty and more humid air?