What does this switch actually do? Does it work? I'm not sure if I turned it all the way up or all the way down as there is no arrow or mark on the switch. I ran it for 2 days and it didn't use any water to speak of. I live in Colorado Springs and it is VERY DRY here. My bedroom humiidfier runs out of water before 8 hours (all night running). I don't think this machine works. Any help? Thx. Bev.