AOS 2055A Automatic Air Washer

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List Price: $359.99
Sale Price: $329.99
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For details, including photos of the internal workings of this evaporative humidifier, look for the 2055 AirOSwiss reviews done elsewhere on Amazon which has plenty of images of the inner workings. To summarize, it's an evaporative humidifier which works by drawing air in through the top via a fan then over a disk pack of about 10 slowly rotating plastic disks which dip into a pool of water, then the air exits the side carrying the humidified air.

Pros: No heated element to worry about overheating when it runs dry, no ultrasonic misting to leave water droplets on carpet/furniture, easy to clean, no filters to be replaced, and it traps air particles on the discs with the water so it does 'wash' the air.

Cons: Evaporative which means it cools (fine for the desert country, not so good in winter in the Midwest), no heating, and the fill valve on the water tank is the stupidest location you can imagine, so that at best you can fill it only 3/4 full.

The other con: They SAY on their website they have a 10 year warranty, yet when I got this thing from Bed Bath and Beyond the plastic shaft inside had corroded from time and was crumbling. It was a major effort to get these guys to agree to replace it. It is NOT SAID on their warranty, but apparently the 10 year warranty does not apply to the rotating disc set (surprise!). I told them they had better put that in writing if they don't want to tick off a lot more customers other than me. They eventually replaced it. Also note, the 10 year warranty does NOT apply to the water tank and its part . . .that's only 3 months.

For $260 bucks or more, the above limitations cut it to a 3 star, even though it's a reliable humidifier that cranks out the humidity from the unit with no filters and very little maintenance. As a personal aside, I can't stand the reviews which deride humidifiers because their hygrometers show no change. Humidifiers can only be evaluated by how quickly they put water into the air . . . the ultimate humidity change is depending on the room's air flow, items of absorbency, and atmospheric conditionsnone of which are in the control of a humidifier!

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If you are in the market for a humidifier and are willing to pay a premium price the AOS 2055A merits serious consideration. If you are primarily interested in air purification you should look elsewhere; while air washers do remove a small percentage of large particles from the air (the rotating disk sweep some particles out of the air) they don't have the flow rate needed to compete with a good HEPA filter and they don't remove the full range of particle sizes a HEPA filter will. Additionally, a good HEPA filter will capture 80-99+% of the particles that enter the system (depending on the quality of the device) whereas there is no guarantee that a particle entering an air washer will make contact with one of the rotating disks. The primary benefits of the rotating disk design don't come from air purification but rather from the increased surface area available for evaporation that permits a smaller and quieter fan to be used in their design. Also, the action of the rotating disks helps prevent the water in the basin from becoming a stagnant breeding ground for mold, bacteria, etc.

Air-O-Swiss has a tendency to slightly inflate the statistics for this product. The box claims that it operates on 20 W of power whereas the documentation admits that it actually needs 29 W on the highest setting. The noise level is stated as being below 25 dB; this may be true of the lower setting which is indeed very quiet, but the higher setting is well above this level although it is still quiet compared to most evaporative humidifiers. The water output is claimed to be up to 3 gallons but 2 to 2.5 gallons of output in a fairly dry room (RH of ~35) seems closer to the truth. Finally, the capacity of the storage tank is effectively only about 1.1 gallons because it is virtually impossible to fill completely. The actual performance statistics compare quite favorably with other humidifier designs so I don't see why the manufacturer feels the need to exaggerate.

The system is well designed, very quiet, easily cleaned, and provides a decent amount of humidification (of course, if you want to humidify a large home you should expect to need several of these units). This is the only humidifier I have owned that didn't occasionally leak. The primary deficiency is that it lacks a built-in hygrometer so it will only shut off when it runs dry. In practice, however, hygrometers are often very inaccurate so many products that include them are still not reliable enough to operate in an automated mode. It would have been nice if the unit had 3 speeds and a larger storage tank, but these are minor quibbles. This product sells for a premium price but it is a solid performer and is worth the cost.

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Purchased this about 5 years ago (or similar model with rotating discs and digital humidity reading) for about $350. As far as I can tell, this is the best humidifier on the market. Tried a few other models including heating element, ultrasonic. wick, and this is by far the best. Have run it almost non-stop in the winter for a number of winters, and also ran it a little bit in the summer if my room gets too dry with the air conditioners in a former apt that had underpowered AC. It has kept my room at about 40 percent year round. Like any other humidifier you can't have any drafts coming in from outside or a window open in the winter or it won't help you much.

It has had NO problems over the last 5 or so years. It is also very energy efficient and quiet and looks nice. The ultrasonic humidifier created too much white dust for me, and the mist could damage furniture. A wick humidifier caused some water damage on a floor after it cracked open.

You do have to clean the water out periodically by pouring it out and gently cleaning the base, and once every month or few months or so in the winter take all the discs out and wash them with something like ecover dish washing detergent and a sponge. I keep an upright piano in tune almost completely year round. I would recommend a second separate humidistat if you are tightly controlling the humidity in your home for a piano, or other such application. For just comfort, the built in humidistat is fine, though you have to increase the setting to a higher humidity setting in the winter to keep the same room humidity, and lower the setting or turn it off towards the spring/fall and summer.

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My husband has severe allergies. He has used this brand and model of air cleaner for a long time. It helps keep the air in our bedroom in good shape and his allergies bother him less with it running. We even take it with us when we visit our families.

He does have to clean it regularly to keep the scum and/or mold down. This would be true of any appliance of this type. Just be aware of that before you buy.

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Not a bad unit, but small water tank. In my house I use two on the first floor, and I need to fill them each three times a day. As for "cleaning the air", I think that is definitely overblown. The ONLY thing I find in the base of the unit, which needs to be addressed not monthly as they state but weekly, is the calcium build up. No dirt in there, only crusted deposit from the water going through there.