When it comes to choosing the best humidifier overall, expert reviewers typically place ultrasonic models at the top of their lists. These best of these machines are capable of producing warm or cool mist. They are also quieter than other types of humidifiers and lack a messy-to-clean filter. Their downside is a higher propensity to emit dust -- an especially annoying problem for those with hard water. Remedies include using distilled water or a demineralization cartridge, if one is offered.
Among the top choices, expert reviewers point to the Air-O-Swiss AOS 7135 (Est. $180) ultrasonic humidifier. This humidifier can produce warm or cool mist and is suitable for rooms up to about 650 square feet. The water tank on the Air-O-Swiss AOS 7135 is detachable and transparent, which makes it easy to clean and allows you to keep an eye on the water level. A digital humidistat allows you to adjust the humidity in the room to your desired level. This humidifier comes with an Air-O-Swiss AOS 7531 demineralization cartridge (Est. $16), which needs to be replaced every two to three months (or more often with hard water) to prevent the release of minerals into the air -- a frequent complaint with humidifiers. There's also an Air-O-Swiss AOS A200 Hydro Cell (Est. $30), which should be replaced every two months or so to prevent bacteria from taking root in the water tank between cleanings.
The Air-O-Swiss AOS 7135 does extremely well in professional reviews. It's a recommended pick by one independent expert, and is named the best humidifier overall by TheSweetHome.com. Seamus Bellamy writes that the AOS 7135 is quiet, efficient in raising humidity levels, and can be set to maintain a safe humidity level, and then left alone until it's time to refill or clean the humidifier. The expert review at AllergyBuyersClub.com notes that more of the site's staff members own the AOS 7135 than any other humidifier it sells. "All in all, the Air O Swiss 7135 is a sensible and reliable solution for anyone looking to improve the air quality in their home or office," they say.
User reviews, however, are a bit of a mixed bag. Amazon.com hosts the most of these, and owners are of a decidedly split mind. The majority is mostly to completely pleased, however this humidifier's overall score is dragged down by owners that complain about leaking, inconsistent humidity, or mineral dust; the latter is especially a problem for those with very hard water or who skip using the demineralization cartridge. At AllergyBuyersClub.com, feedback is a bit better -- a 4.2 star rating with 78 percent of buyers saying that they would recommend the AOS 7135 to a friend.
AllergyBuyersClub.com names the Air-O-Swiss Ultrasonic 7144 (Est. $ 200) its best humidifier. It is also named as a "splurge-worthy pick" in the comparison tests conducted by the Good Housekeeping Research Institute, and it earns a score of 8 out of a possible 10 from Wired. But user reviews for this humidifier are once again mixed (as they are for virtually all humidifier models, regardless of price). Compared to the AOS 7135, the AOS 7144 is a bit sleeker, with a more sophisticated silver/black finish (the 7135 is blue and white). Both offer the same 3.5-gallon-per day output, but the AOS 7144 has a smaller tank (1.5 gallons versus 2 gallons), which means you'll be refilling it a little more often. Availability for the AOS 7144 has become limited, but the model remains current and can be purchased from Air-O-Swiss.
For smaller rooms (up to 500 square feet), the SPT SU-4010 Ultrasonic Dual-Mist Warm/Cool Humidifier with Ion Exchange Filter (Est. $80) earns excellent ratings across the board in one independent test and is named a Best Buy. This SPT (formerly Sunpentown) humidifier is also the budget pick at TheSweetHome.com and is highly rated by AllergyBuyersClub.com. Like the Air-O-Swiss 7135 humidifier, it is designed to produce cool and warm mist, with variable humidity levels. However, this model does not include a humidistat. It does have a demineralization cartridge (called the Ion Exchange Filter), which should be replaced every six months. Other features include overheat protection and a split rotating nozzle to direct mist in two directions simultaneously. This model is energy efficient (using up to 43 watts on the cool-mist setting and 90 watts for warm mist) and very quiet.
However, we once again noticed reliability complaints. At Amazon.com, more owners are happy than not, but we saw reports of humidifiers breaking down anywhere from a week to four months after purchase, and we also read several reports of leakage, often severe. However, some owners identify the source of the leak being improperly seating a sealing ring after filling and that carefully following the maker's refilling instructions should eliminate the problem.
Elsewhere in this Issue:
Best Cool-Mist Humidifiers: If you have a smaller area to humidify, or want to keep an eye on your bottom line, these evaporative cool-mist humidifiers make terrific choices. Here are the best of the best.
Best Whole House Humidifiers: Is your whole house as dry as a tent in the desert? These whole house humidifiers will get things moist in a hurry.
Best Warm Mist Humidifiers: We look at the pros and cons of warm-mist humidifiers, and make our recommendations for those who find warm moisture preferable to cool.
Buying Guide: Need more information before deciding on a type and model of humidifier? You can find the answers to many common questions regarding humidifiers in our helpful Buying Guide.
Our Sources: These are the sources of expert and user reviews we used to prepare this report on humidifiers. We rank them in order of timeliness and helpfulness.