To answer some questions in other reviews:
WHIRLPOOL MODEL AVAILABILITY:
The following Whirlpool models are both still available, (as is a third less powerful model, the 250, which uses different sized filters):
Whirlpool Whispure 450 Air Purifier (AP45030K), also 315-CADR
Whirlpool® Whispure 315-CADR Air Purifier with True HEPA Filter, AP51030K (this page)
Both of these models use the same replacement filters:
Whirlpool 8171434K Large Air Purifier Carbon Pre-Filters
4-Pack and the Whirlpool 1183054K Hepa Filter, Large (links below)
CADR RATINGS EXPLAINED:
The Clean Air Delivery Rate (CADR) comes from measurements conducted by the Association of Home Appliance Manufacturers (AHAM), and is a measure of the amount of particle-free air being delivered into the room. It is the best measure of the true cleaning capacity of the air cleaner. The higher the CADR, the larger the room that can be effectively cleaned. A loose equation is: CADR x 1.5 = sq. ft. room size.
This is important because manufacturers can list any "room size" rating they choose, regardless of CADR rating. Thus you might have one product claiming it can effectively handle a 400 sq. ft. room, while another product says it can handle a 200 sq. ft. room, yet both have the same CADR ratings. So always use CADR ratings rather than room size ratings in making your comparisons.
That said, air cleaners are usually advertised with the room size for which they are recommended. If this accurately matches about 1.5 times the CADR rating (as in Whirlpool's case and with many other top brands like Honeywell), just keep in mind that this recommendation is based on the the unit's ability to provide 5 or 6 Air Changes Per Hour in a room of that size.
Thus, a 250 CADR rating x 1.5 = 375 sq. ft. room size, means the unit provides 5 6 complete Air Changes Per House in a 375 sq. ft. room sized room. Simple enough.
But for allergy-sufferers it's a bit more complicated than that. This standard rate is sufficient to decrease particle levels in the room by about 70%, which isn't enough for allergy sufferers. A larger unit in the same size room can produce 8 or more air changes per hour, decreasing levels by 90% or more, again, depending on properly matching CADR to room size. This is the correct target in medical situations.
Finally, Please Note: the CADR rating applies to the HIGHEST fan setting of each unit.
MODEL COMPARISON:
The AP510 on this page, is Whirlpool's slightly beefier model that has the following additional features: turbo and sleep modes, 1 extra fan setting, and electronic vs. the 450's manual controls.
Since the CADR ratings of the two units above are the same, the additional cleaning capacity over the Whirlpool 450 model must relate to a higher fan speed (and AC wattage draw) at the maximum setting of the Whirlpool 510. Again, keep in mind that if you want to effectively clean a room as advertised, both units will have to run at the highest speeds.
Sleep mode allows a user-defined setting for sleep hours, wherein the purifier automatically flips itself to the lowest fan settings for that time period, allowing the unit to be run continuously during sleep hours. After sleep mode expires for that period, it flips itself back up to the standard setting. (If anyone has info on Turbo Mode, I'd be grateful and will update this review).
As noted by another reviewer, the AP510 (this page) is Consumer Report's top-rated air purifier for home use in 2010, along with the Hunter 30547. (Consumer Reports September 2010, p.44, "Lab Tests: Air Purifiers Our Tests Reveal Which Ones Deliver"). I searched for the Hunter unit on Amazon, and it is not available as of 11.5.10. Amazing the company would allow that, given that they should be selling like hotcakes after CR's review. It's typical price is $350, and it has ratings for rooms the same size as the Whirlpool AP510 on this page. (I could not find the CADR rating for the Hunter, but assume it must be the same or similar to the AP510).
UPDATE: The Hunter model has been discontinued, and they sell new models now that rate similar and which are sold here on Amazon: Hunter 30401 QuietFlo and Hunter 30402 QuietFlo. The 401 model is programmable, the 402 is not. The Hunter site lists the programmable 401 at a higher price than the 402, while Amazon sells it for a lower price than the 402. Go figure. Check Hunter's site for more details.
HONEYWELL'S TOP UNIT:
I think of all the many models I reviewed under $600, the Whirlpool is the way to go. Excellent product, strong company backing, easy to find filters, great price. It is all you need, IF the only thing you need is effective particle removal. For serious odor and chemical removal, look to more expensive units.
But one other model that is a very strong contender for home use is the Honeywell 50250 at only $159 on Amazon. It has been very well received and has great reviews here on Amazon. It's faults appear to be high power consumption and noise. The Honeywell did come in at No. 9 in the same Consumer Report's review (out of 20 rated), where they noted it needed to be run on the highest fan setting to be effective, which caused it to be very noisy. As already discussed, all CADR ratings refer only to a unit's highest fan settings, no matter which brand you buy.
Noise is a problem. However, where the Honeywell excels besides a great price, is that their canisters are sealed and therefore they do not tend to leak any dust back out of the unit and into the exhausted purified air. Many other cheaper models do, including the Whirlpool models at least according to my online research. (If you can disprove this, please let me know). This is a big deal to me, though it may not be to other users, because I have asthma and I can't have the "vacuum cleaner effect" with house dust actually blowing up into the room from an air purifier.
UPDATE: I purchased 2 Honeywell 50250 units, and was blown away by the quality of simplicity of design on the units. If only everything was made this well and this easy to use and work with! Filter change was a total breeze. The filters are pretty loud, which doesn't bother me, but it's something you should note if you want something quiet. However, I had some strange problems with the exhaust on both units, and am working with Honeywell right now. The problem seems to be an anomaly and not normal, so I don't want to mention it here as I think it's just a fluke. One thing I can say, is that Honeywell offers AWESOME customer service, and has been great to deal with on the phone. :D
I hope all this helps you with your purchase. I've been researching air purifiers for over a month and I know how confusing it can be!
Please note, that running an air purifier like the 4 discussed here at top speed 24/7 will add a whopping $40 to my monthly electric bill here in San Diego. Do your own research before planning to run your own brand choice full time. As I mentioned before, top speed is required to achieve the CADR ratings advertised.
Links here:
Whirlpool 1183054K Hepa Filter, Large
Whirlpool 8171434K Large Air Purifier Carbon Pre-Filters, 4-Pack
Whirlpool® Whispure 315-CADR Air Purifier with True HEPA Filter, AP51030K
Whirlpool Whispure 450 Air Purifier (AP45030K) HEPA Air Cleaner
and...
Honeywell 50250 99.97% Pure HEPA Round Air Purifier
Honeywell 38002 Enviracare Universal Replacement Pre-Filter
Honeywell 24000 Replacement HEPA Filter
and...
Hunter 30401 QuietFlo True-HEPA Programmable Air Purifier
Hunter 30402 QuietFlo 402 Air Purifier
Hope this helps!
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Works like my brand new Oreck proshield... no issue what so ever. Yeah!! I need these in my bedroom and office because of the animals and my asthma. No one wants to give up their love ones because of their health, so I got these and I have no issues.
I experienced many of the same problems with my itouchless trash can about a month after purchase. It started acting erraticly one day so I thought the batteries might need changing. I did that and everything seemed fine. I shut it off that night and when I turned it back on in the morning it did not work right. It would open normally, but would not close unless I pushed the close button. Sometimes it would stay closed, but other times it would open at random or open right back up as soon as I closed it. I went back through and read all of the reviews on Amazon. I e-mailed the company(itouchless) and called the 800 number I found on one review and left a message (it was on a Saturday when I called). The funny thing was, before I got a call back, the trash can started to work again. All I did was push down on the cover one time after I closed it with the close button. I don't know if that is what did it, but I haven't had a problem since. I was a little nervous that customer service at itouchless was not going to be helpful because many of the reviews stated as such. I didn't have that same experience. I got a phone call and an e-mail 3 days after contacting them. This is what the e-mail said:The sensor could be affected by moisture,stain or fingerprints. To fix the problem please try:
Only reason I have rated this item as a four is I have only had it a short time. The experience as well as quality is as expected. Good item for the price.
This is NOT made by Honeywell as described. It is a generic replacement filter and it has a terrible odor. The item also arrives via US Mail, yet you will be charged UPS/FED-EX prices.
I ordered these after wanting them for so long. I received them and they were bent, but I let them know and they sent me replacements immediately. I was very impressed. :)
The other reviews are very thorough. Just want to add a note that they are accurate.