My raised ranch is 3 feet in the ground, 3 sides. one end is above grade. I have insulated the walls and the space is now living space. Was not designed for that when the house was built. Only the floor is not insulated. Every year about this time,for the past 37 years, we experience issues with dampness. (nothing gets wet, not even paper on the floor) So, if it very humid outside, I have to button the first floor up and run a dehumidifier. That cost a bundle and the air is a warm stale air I don't care for. when it gets a little cooler, I can open the place up, then later run the pellet stove. That all works except for 3 months of the year. Anyone with any experience of using an air exchanger as an alternative to using a dehumidifier. What units work OK What are the cost factors?