I was a bit sceptical about this but after chatting to Nuaire and my friend who has one I decided to buy one. I suffered daily with condensation on the inside of the windows, but once the PIV was fitted the condensation has disappeared. I haven’t had a need to use the heater yet but will probably do that as the outside temperature has dropped. The installation is straight forward but I did struggle as my loft space is restricted and not much head room. Would highly recommend this item. If I was to buy again I probably would not have bought the heat version. 5 stars