Any ideas on what I might be doing wrong?

[yourchoice]

Originally Posted by bobarian

70% Rh indoors seems exceedingly high even if you are running a humidifier connected to your central heating/air. If you are only using silica gel I suspect your Rh is actually much lower than you are measuring.

Originally Posted by hotreds

I hope your house isn't at 70% humididty- there would be a great danger of mold on all your furniture etc at that high a humidity!

I think it's very unlikely (putting it kindly) that your indoor humidity is anywhere near as high as you think, especially this time of year being in the Great Lakes region. During the summer, in a basement, after a heavy cool rain (when the A/C isn't running), maybe...and if so you should have a dehumidifier running.

IMHO, a properly calibrated hygrometer sounds like a must.