Found this unit not as straight forward to fit as the instructions make out. If fitting the diffuser to a new plasterboard ceiling it should be straightforward but with an old lathe and plaster ceiling it was a fiddle. Could have done with some more material sticking through into attic to accept the heater unit. I used a straightened wire clothes hanger instead of nylon line supplied to suspend filter unit. Getting the flexible ducting to fit on this filter unit took two of us! Felt a bit like fitting a 26inch diameter tyre to a 27inch dia rim, the nylon ties are fairly substantial so are a bit stiff to tighten to keep ducting in place. Have tried it out, but set fan to 4 setting which seemed too much as blast of air coming through was cold, temp gauge registered 59deg with humidity at 61%. Before fitting humidity had been up to 80% with 62degrees although temp outside was warmer. We have an unfelted attic so plenty of air but this time of year (November) cold. Will try increasing temp and reduce flow. This might quieten the fan as well because at 4 setting I wouldn't say it's silent.