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Best Ultrasonic Humidifiers

By: Carl Laron on October 27, 2017

Ultrasonic humidifiers earn top marks from reviewers

When it comes to choosing the best humidifier overall, some (but not all) expert reviewers place ultrasonic models at the top of their lists. We highlight some models that produce cool mist only in our discussion of the best cool mist humidifiers. However, feedback tells us that the best ultrasonic humidifiers are those models that are capable of producing either a warm or cool mist. Like all ultrasonic humidifiers, 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.

In the cool mist/warm mist ultrasonic category, we found the best feedback for the SPT SU-4010 (Est. $80). It earns Excellent ratings in all metrics save efficiency at ConsumerReports.org, with only a Very Good rating in efficiency keeping it from perfection. It's also named a Best Buy. It's also the Editors' Choice selection at BabyGearLab.com, where Ellen Baker reports that the SU-4010 was "a strong performer in all of our rating areas with an ability to effectively and quietly humidify both large and small rooms via a nice combination of features and overall design."

It's also the best liked ultrasonic humidifier at TheSweethome.com. Though the editors think that evaporative humidifiers (covered in our discussion of best cool mist humidifiers) are a better value, especially for humidifying smaller rooms, the SU-4010 is their pick for spaces of 400 square feet or larger (up to 500 square feet, as rated by the maker). They note that it performs similarly to models costing twice as much, but warn that it's easy to over humidify a room, especially a smaller one, if you are not careful.

This SPT (formerly Sunpentown) humidifier is designed to produce cool and warm mist, with variable humidity levels. This model does not include a humidistat to automatically turn the humidifier on and off depending on the humidity levels in the room, but that's not a deal killer in any of the expert reviews we saw.

The SPT's pluses include a demineralization cartridge (called the Ion Exchange Filter), which should be replaced every six months to prevent the release of minerals into the air -- a frequent complaint with humidifiers. Other features include overheat protection and a split rotating nozzle to direct mist in two directions simultaneously. Like all ultrasonic units, the SU-4010 is very quiet.

While ratings are high for the SU-4010 among experts, there are some disagreements. At TheSweethome.com, it's held back a little by "those daily tasks that hold back several humidifiers—cleaning and refilling," but others have fewer qualms. At BabyGearLab.com, it's rated as above average in terms of cleaning ease. Pluses include a water tank opening that's wide enough so that you can fit your hand in sufficiently to wipe down most surfaces. For harder to reach spots, "We were happy to find that … this humidifier comes with a small brush to clean the ultrasonic vibrating plate as well as some of the other small spaces in the base, and that the brush fits neatly into the base for storage," Baker says. It also earns high ratings from Baker site for Ease of Use, even when refilling -- including kudos for a water tank with a "sturdy built-in handle." It also earns a top grade for convenience from ConsumerReports.org, though not without some caveats. Low points they cite include the lack of a power indicator and a gripe that the unit does not automatically shut off when it is out of water. The editors there also warn that the unit may be a little easier to tip over than some models.

User reviews are mixed, something that's unfortunately commonplace when it comes to humidifiers. 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 as being improperly seating a sealing ring after filling, and note that carefully following the maker's refilling instructions should eliminate the problem.

If you have a larger room to humidify, the Boneco 7135 (Est. $180) ultrasonic humidifier continues to deserve consideration. If the maker seems unfamiliar, this is the current branding for the Air-O-Swiss line, and the unit is identical in every way to the Air-O-Swiss AOS 7135 that has been highlighted in past reports.

The 7135 can produce warm or cool mist and is suitable for rooms up to about 650 square feet. The water tank on the Boneco 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, though testing by TheSweethome.com found accuracy to be wanting. This humidifier comes with a Boneco 7531 demineralization cartridge (Est. $20), 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 a Boneco A200 Hydro Cell (Est. $20 for two), which should be replaced every two months or so to prevent bacteria from taking root in the water tank between cleanings.

The Boneco 7135 (under its old Air-O-Swiss brand name) is a recommended pick by ConsumerReports.org, and its second highest rated humidifier for large rooms. It tests out worse than the SU-4010, the top rated choice there, when it comes to convenience -- rating only Good in that regard and with a note that user feedback indicates that the unit is hard to fill and clean (again, both common humidifier complaints). Like the SU-4010, the Boneco is aces in all other regards, and beats it with an Excellent rating for efficiency. The expert reviewer at AllergyBuyersClub.com notes that more of the site's staff members own the Boneco 7135 than any other humidifier it sells. "All in all, the Boneco by Air O Swiss 7135 is a sensible and reliable solution for anyone looking to improve the air quality in their home or office," the reviewer says.

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. Many are mostly to completely pleased, however this humidifier's overall score is dragged down to 3.4 stars overall (based on nearly 630 reviews) 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 4.3 star rating based on more than 55 reviews, with 80 percent of buyers saying that they would recommend the Boneco 7135 to a friend.

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