Bests & Worsts Reviews from Amazon

When I first purchased this product I was excited at the thought of filtering dust, allergens and other contaminants from the air in my room. It tends to accumulate dust quickly so I bought this air purifier in hopes of alleviating the problem a bit. For the first six months the purifier worked very effectively. I ran it 24 hours a day nonstop as recommended (if I ever had to turn it off for any reason I covered the exhaust vent with a microfiber cloth so as to not let dust seep into the unit). I set the fan speed to high when I left home, medium when I was home and low when I slept. I cleaned both the outer filter and inner HEPA filter several times a week. Dust would cluster into a lint-like texture and accumulate very quickly on the outer filter; this prevented a significant amount of dust from even making it through to the inner HEPA filter. I noticed somewhat of an improvement in the air quality of my room (11.5 ft. x 8 ft.) during this time span. After about six months, the air being exhausted from the purifier started to smell strange. It's hard to describe the smell, but the best way I can put it is being a "dusty" smell; this description makes sense in context because the interior mechanical components of the purifier were now caked in dust (explained two paragraphs down). The product listing claims that the HEPA filter never needs to be replaced, but I cannot believe this to be true. It either needs to be replaced after a period of time, or it is not as effective as it should be to begin with. When I first purchased the purifier, the filter was white; it is now a deep charcoal grey, although this is not unexpected. Perhaps this isn't the best comparison to make as they are constructed of different materials, but air filters for many other devices need to be replaced after a period of time (automobile engine, lawn mower, vacuum cleaner, etc.). Cleaning them will extend their lifespan, but repeated cleaning will only work for so long. That seems to be the case with the filter for this air purifier as well. As I said mentioned earlier, I cleaned both filters regularly and did not allow too thick a layer of dust to build up. I read another customer review mentioning that their purifier became filled with dust and grime over time, and this is exactly what happened with mine. Looking down the exhaust vent I could see dust covering the interior surfaces, both on the purifier housing and the mechanical components. I tried blasting the dust out with compressed air, but even 185 PSI of air pressure would not move it. It had become caked down to all surfaces and had a grime-like appearance. After opening the purifier to have a better look at things (it is held together by hex security screws) it was confirmed that every internal surface was covered in caked dust. This explained the "dusty" smell that the purifier was emitting. I unscrewed and pulled several components out (fans, motor) to get better access to every surface. Everything is very cramped inside of the purifier, and it's difficult to reach all surfaces, but I scrubbed out the majority of the dust using isopropyl alcohol. After reassembling the unit I ran it again--while the smell was less noticeable from a distance it did not completely go away. I am unsure of whether the HEPA filter was letting contaminants get through the entire time, or if it eventually let them get through as it became less effective. The bottom line is that the purifier seemed to be working great in the beginning, but after six months it began to make my air quality worse. Edit (March 3, 2011): I bought another unit several months ago. When the first purifier functioned properly it worked wonderfully, so I wanted to give it another go. I thought perhaps I'd have better luck if I were to clean the filters even more frequently than I had already been doing, which was multiple times per week. This time I cleaned them almost every night. Sadly, and strangely, this purifier began emitting the same funny smell as my first one, but after an even shorter period of time. I opened up the unit and saw that the interior had been caked in dust in the same manner as my first purifier. This time I was even more thorough with the isopropyl alcohol cleaning. I removed every internal component and took them completely apart in order to be able to get almost 100% of the dust cleaned out. Unfortunately I was left with the same result as the first time around and the purifier continued to emit the same smell. Edit (July 7, 2013): I cleaned up and rewrote much of the review for readability and to add more details of my experience with the product. I also wanted to note that I purchased the Hamilton Beach 04383 air purifier in October of 2012 and it has worked well for me. Many people seem to have great experiences with this Honeywell air purifier, but I just cannot recommend it at all. I initially had my rating at three stars since my first unit worked very well for six months, but I have to drop it to one star as the overall experience between my two purchases is completely unacceptable. I went beyond the recommended cleaning parameters for both units and they still went bad on me.