Buy a dehumidifier or create a register in the return and supply plenums in a damp basement?
I have a 1200 sq ft basement. 1/3 of it is crawlspace under an addition to the house with two former basement windows connecting it to the rest of the full height basement. I have insulated the walls in the basement and crawlspace is covered all the way to rim joist with 20mil reinforced poly to reduce radon.
Yesterday I was inspecting the crawlspace and found dew on poly in the lowest parts of the crawlspace. I do monitor moisture in both crawlspace and basement and we are lately at 78%.
I wonder if I should create a register in the return and supply plenums. Or do I just pay up for a 50-pint dehumidifier?
P.S. I am in Northeast