I already have one which runs constantly in a room with a piano in it. My house is generally damp as it has solid walls and I'm having problems in the rest of the house due to the wet weather. As a result I bought a new, more powerful one that B&Q have just started doing apparently. It's supposed to be able to produce up to a huge 60 litres a day so I'm expecting it to be very effective hopefully. The only issue is that's it's a bit loud on the highest setting but if it cuts down on mould and other effects of damp, it's worth it