This is a used Drimaster Heat PIV unit. This was installed in our loft to solve a condensation issue on the first floor, which it did. We had it working for a couple of years with no problems, and it was removed when we recently converted our loft. The filters could do with a wash, but are fine. It comes with the vent unit for the ceiling, which should be mounted in the middle of the house for best results.It needs to be installed by a qualified electrician (although it's quite straightforward). I don't have the instruction manual but this can be found online. But please ask any questions, and check my feedback - it's all good!