i have a unit from Freshaire/Eco_Quest approx 18"h x 20"l x12"w table top - handles 2500 sf house (programmable for size of room or house up to 3000 sf, low Db, uses a replacable prefilter, a UV light and a metal grid. been running 4 yrs 24/7 - sent to factory once for refurbish for superfine dust from cat litter grinding up the elect motor (hence the prefilter pads, and now no worries. several sizes. spendy, but does the job.