Get something like this http://www.radioshack.com/product/in...uctId=11361230 I have a older version with one sensor in our attic, one in our garage, that I used to have that one down in our basement. Our house stays around 55% to 62% Rh in the main floor and basement. I have seen it get as low as 39% for a day, but next day would go back to 55%.
You really do not want the Rh too low, due to it will cause more problems than good. Especially with flooring.
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