Initial consult was great then let down immensely by the chosen installers who postponed several times then only part installed as they said that measurements weren't taken properly so had to order more product, then we heard nothing back from them and had to constantly chase. In the end I had to ring our consultant who wasn't even aware that the install hadn't happened (I would have thought a consultant would have tracked this). I can't remember how long it took now but I think it was about a month of me chasing with the product being part installed. Then we weren't left with instructions on how to use it, so again I had to contact the consultant who emailed instructions and we've never heard from them again to see if we were happy. We had a heat transfer as well as I-Vent installed, but one of our bedrooms upstairs the air that blows into it through the night is so cold it's like aircon that I'd turn it off if I could, but I don't think we can shut down just one vent. We have less condensation so the IVent product is working, however all in all I would not rate or recommend Harrisons due to the experience.