I purchased two of these units and have yet to see any change in relative humidity in the several locations I have tried them out. The units do slowly collect some water, evident when they are recharged and show a bit of condensation in the viewing window, but the reality is they are not removing anywhere near a substantial amount of moisture. I have used a hygrometer, and even in a tiny enclosed space did not see the relative humidity budge from its 60% level of the surrounding air.