Wow, 24 years in business and I've never run into this. Humidity. Way to much humidity in 2 separate homes. Both homes have high eff. systems with variable speed fans, humidity controls on the Tstats etc. Fairly modern construction, both less than 20 years old, not overly tight. Trees that were planted when the house was built are now shadowing the home very well. Crawl space is moist but not excessive. One retired couple and one young family. One 2 story and one ranch. Both duct systems are very tight with probably less than 2% leakage. Yet both homes are running humidity levels above 60%. ?????????? Any ideas????? I even had the manufacturer rep come out and look at one of the systems and he helped set it up to max humidity control.