I had a cust this past week who had condensation on several windows. This was a 4 thousand SF plus home...4 years old...flash and batt...geothermal...steam humidifiers and his monitors said he was at 20%. My Extech meter said he was at 34%. Regardless of whose meter was correct the windows were telling us that the RH was a bit too high. The outside temp was 38. He wants to purchase a RH meter that is very accurate so I'm hoping you pros can give me some advice.