I am pretty set on purchasing a Positive Input Ventilation (PIV) fan for my new home. The house does suffer from minor damp in places, and there are hayfever sufferers in the house. Installing a PIV fan should help reduce the damp, and give better general air quality in the home.
I remember reading somewhere (although frustratingly I cannot find it now to cite) that when using a PIV fan you should not use an extractor fan in wet rooms.
I kind of see the logic in this, in that by definition the positive pressure within the house should force the damp air out. However, surely an extractor fan would not hinder the effectiveness of the PIV fan (not by a significant level anyway)? The way I see it, it would be no different to having an input and exhaust fan on a computer tower (I love using the computer analogy when discussing PIV).
The only reason I can think of, is that the gaping hole of the extractor fan to the outside world would make it much harder to create the positive pressure within the house? However, my knowledge of physics and fluid dynamics doesn't stretch this far, unfortunately.
Does anyone else have PIV fans installed, and if so do you have extractor fans in wet rooms (or any other rooms for that matter).