I had two Raumentfeuchter ordered to master to the moisture on the windows in the bathroom and in the bedroom. In the first week I was very surprised, especially in the bedroom where overnight (as we have the heating off overnight) had always formed much condensation on the windows, it is much less become (only a very thin strip Kondesnwasser). But in the weeks that followed, the effect was felt less and less. What is the reason can not say exactly one. The container I empty out, but it may not really be so. Maybe this stone is more effective if you bring him fresh out of the pack and it's completely dry, because now is our course around moist. I think it was worth a try and I still feel that the humidity condensation on the windows without the dehumidifier would be more, but I'm not thrilled (more). Good that I have the Renz Sion only now written :)