Purchased this Alen 75i because wife has COPD issues,had in the past tried several other Air Cleaners with similar results lotta hype and little action,Have had this Alen unit working for a few days now and truthfully the first day after a few hours I thought it was not even working had to walk over and check its so quiet,I purchased the the 75i because we have an open flloor plan and it said 1300 sq feet coverage,to my surprise after checking to see if it was even still running I noticed that in our family room which is 24x25 with a 14 foot vaulted ceiling the air flow on LOW Speed had the Ceiling Fan paddles turning ...............Amazing So far it seems like little Hype lotta action ,will get back with further comments after few weeks ...............