The Best Humidifier
For the third year running, we’ve tested portable humidifiers—and for the second year running, the Honeywell HCM-350 is our pick as the best humidifier for most people. Like most machines we tested, it humidifies the air quietly, reliably, and efficiently. However, the Honeywell is the easiest model we’ve ever found to fill and clean—and that’s paramount, because cleaning and filling are the two things you do the most with any humidifier. Also, unlike nearly every other humidifier, the HCM-350 is designed so that every part that touches water is free of electronic components and sharp angles. And the HCM-350 is the only humidifier we’ve found that has a seamless, molded reservoir, which eliminates a problem common in inferior models: leaks.
Our runner-up model from last year (the Sunpentown SU-9210), our “also great” model (the SPT SU-4010), and upgrade pick (the Venta LW25 Airwasher) also remain the same. We’re coming to the realization that there’s not a lot of innovation year-to-year in humidifier design, nor any quantum leaps in performance.
Our latest round of testing featured eight new models, plus a retest of the Honeywell and our runner-up, the Sunpentown SU-9210. Most of the new models fell into our existing evaporative and ultrasonic categories, but in response to reader requests, we also looked at three warm-mist (or steam) humidifiers and made a recommendation in that category: the Vicks V750. It’s more solidly built and able to stay cooler to the touch than competing models, and it delivers an impressive amount of vapor. While overall we prefer evaporative “cool mist” humidifiers—they’re significantly more energy efficient and have no hot parts at all—some people like the feeling of warm mist; the Vicks delivers reliably.
We tested the humidifiers in a climate-controlled space while regularly logging the temperature, humidity, and particle count (where applicable). Then we evaluated them for ease of use and cleaning, which was just as important as humidifying power. It’s hard to overstate how annoying it can be to clean most humidifiers being sold today. That’s unfortunate, because regular cleaning is essential to achieving optimal (and safe) performance. A typical humidifier is full of nooks and crannies that funky stuff loves to grow in. Because some of those dirty parts house the electronics, they can be even more difficult to clean than usual. As such, the fact that the Honeywell is specifically designed to avoid those issues and make cleaning easy is a huge deal.
The Honeywell uses evaporative technology (as opposed to ultrasonic or warm mist), which means you will never run into issues with white dust, pools of water around the base, or over-humidification. While it doesn’t have the horsepower to take a living room from bone-dry to subtropical in 30 minutes, it can get a large bedroom or medium-size living room up to a comfortable level of humidity in less than two hours and then keep it there.
As it has been among the best-selling humidifiers on Amazon for quite some time, it’s unlikely that the Honeywell will become unavailable. But if it does, the Sunpentown 9210 is our runner-up pick. It performs very similarly to the Honeywell and is easy to clean because it also has no electronic components inside that touch water. It even adds a humidistat (which is accurate, according to our testing). However, the 9210 costs a bit more up front, has annoying beeping buttons, and lacks a one-piece reservoir, which could lead to leaks in the long run. Like the Honeywell, its evaporative humidifying mechanism doesn’t have the same horsepower as an ultrasonic model. When your room starts pushing 350 square feet or larger, you’re going to have a tougher time getting a comfortable level of humidity with an evaporative humidifier. If you’re willing to deal with more maintenance, it might just be worth going for an ultrasonic model instead, but our testers preferred the low-maintenance evaporative models, even when it meant living with slightly under-humidified air.
In the past we’ve recommended ultrasonic models because they are almost silent as opposed to just “really quiet.” But after further head-to-head testing, it became clear that evaporative humidifiers are a better value for most people.
Ultrasonic models can spread an annoying layer of mineral dust, and they can over-humidify a room. Evaporative humidifiers solve those problems by design, but they’re not as powerful. Still, if your bedroom is particularly large (around 400 square feet or larger), you might consider trading off easier cleaning for a more powerful ultrasonic model. In that case, the Sunpentown SU-4010 is our pick for best ultrasonic humidifier. Its output is comparable to that of the class-leading Air-O-Swiss 7135 we previously recommended, but it costs about half as much. It doesn’t have a humidistat, but in our testing, the one in the Air-O-Swiss was wildly inaccurate, anyway. However, the SU-4010 is a pain to clean because the water tray is full of sharp angles—a shared trait among all the ultrasonic humidifiers we looked at.
We’d also like to give a shout out to the Venta Airwasher LW25. For around $300 at the time of writing (sometimes lower depending on where you buy it), you get an extremely efficient evaporative humidifier that requires less-frequent cleaning and refilling compared to our other recommendations. Its high upfront cost is somewhat mitigated by its extreme energy efficiency in the long run, but it is still very expensive. Venta recommends rinsing every two weeks with its Venta Water Treatment Additive to remove minerals and thoroughly cleaning every six months with its Venta Cleaner, so running costs aren’t as low as they could be.
The Vicks Warm Mist V750 is clearly built to a price point, with cheap-feeling plastic and wobbly assembly. But hey, it’s cheap, and it performed above average in our testing, raising the humidity levels from 60 to 82.5 percent over a three-hour period. It is a popular model on Amazon, with 3.9 stars and over 2,300 reviews. Two notes of concern: There are several reports of leaks occurring anywhere from a couple weeks to a year after purchase, but the reports appear in less than 10 percent of the reviews. And, as discussed in depth below, there are safety and running-cost concerns associated with all warm-mist humidifiers.
Table of contents
- Why you should trust me
- What is humidified air?
- Who is this for?
- How we picked
- Our pick
- Who else likes it?
- Flaws but not dealbreakers
- The runner-up
- For larger rooms: a silent ultrasonic pick
- The upgrade pick
- If you must have warm mist
- Some general words of caution
- Care and maintenance
- How we tested
- The competition
- What else we looked at
- Wrapping it up
Why you should trust me
My name is John Holecek, and I’ve been involved in climate research since 1999. I’ve studied atmospheric physics and chemistry in locations ranging from the continental US to the Arctic to the remote island nation of the Maldives. These field campaigns were government-sponsored research programs aiming to improve our understanding of Earth’s climate.
In order to test these models in a climate-controlled space, I weather-sealed my home office and installed an air conditioner to maintain stable initial conditions. To evaluate the humidifiers, we used two portable temperature and humidity data loggers and a laboratory-grade particle counter to size up the air washers (read more below in How we tested).
What is humidified air?
You might be surprised to learn that the warm air in your home that feels so dry is not actually any drier than the cold air outside. But it feels drier, because as air gets warmer, more moisture is needed to saturate it. In technical terms, while absolute humidity (the total amount of moisture in the air) is the same inside and out, relative humidity (which is what you feel) decreases dramatically when you artificially heat your home. To raise it to a comfortable level, you need a humidifier.
According to the Mayo Clinic, you’ll want to keep the relative humidity levels in your home somewhere between 30 and 50 percent. Any lower than 30 percent and your environment will become prone to all of the unpleasant side effects associated with dry air (chapped lips, scratchy throat, nosebleeds). But don’t overdo it “just to be safe,” because if you go over 50 percent, you run the risk of attracting mold and bacteria growth.
Who is this for?
If you are bothered by any of the symptoms caused by dry air, such as dry sinuses, nosebleeds, cracked and sore lips, or shocks from static electricity, the air in your home is likely too dry. Getting a humidifier would help ease these symptoms. On the other hand, if you notice condensation routinely forming on the inside of your windows or frequently find yourself having to clean mold off of your walls or window frames, your home is too humid, so you don’t need a humidifier.
If you want to be certain that humidity is the culprit, you can get a hygrometer on Amazon for about $10 (or a hardware store for about $20) and see if your home’s air is under the recommended 30 to 50 percent relative humidity range.
A portable humidifier, like the ones we researched here, is the cheapest and easiest way to humidify your home without needing to deal with an HVAC contractor.
But are you ready to be a humidifier parent?
Humidifying your home involves more than just buying one of our picks and filling it with water. If you don’t take care to maintain it properly (jump to Care and maintenence below), a humidifier can do more harm than good.1 Indeed, the Mayo Clinic warns that “Although useful, humidifiers can actually make you sick if they aren’t maintained properly or if humidity levels stay too high. If you use humidifiers, be sure to monitor humidity levels and keep your humidifier clean.”
Most humidifiers require regular maintenance, and a thorough cleaning every one to three days. There are exceptions, like our step-up pick—but be honest with yourself. If you know you’re not up for this level of regular cleaning and maintenance, you’re better off investing in a whole-house humidifier system linked into your forced-air furnace (consult a local HVAC contractor for more details), or skipping humidifiers entirely. Otherwise, you may end up with a breeding ground for germs.
How we picked
This is the fourth iteration of this guide, so we went into our latest testing with considerable knowledge of what to look for. Once again, we researched popular models on Amazon, reviewed the latest testing from Consumer Reports, consulted Allergy Buyer’s Club, Top Ten Reviews, Best Buy, and ConsumerSearch, and also read the comments from our previous guide for feedback and suggestions from our readers.
This year again, we focused on portable models that work either on the floor2 or a table/dresser because they can be easily added to any environment with no need for installation and can be moved around as needed. These midsize units are recommended for rooms between 200 and 700 square feet, which is more than enough coverage for an average bedroom3 (which is primarily where these are used), and plenty for most larger rooms in most homes. While there are large console units capable of humidifying an entire floor of a home, we didn’t consider them, because at that point, you’re better off installing something directly into your HVAC system. A standalone unit would likely over-humidify some rooms while under-humidifying others.
We looked for units that are powerful enough to humidify 200 to 700 square feet overnight with reservoirs large enough to make it through the night but not so so big as to be awkward to fill in the sink or place on a dresser or table.
There’s also the question of what kind of humidifier to get because different technologies have different pros and cons.
In the past, we had primarily recommended ultrasonic humidifiers because they are nearly silent and capable of outputting moisture at a higher rate than humidifiers based on other non-heated technologies. This leads to higher scores in independent testing conducted by Consumer Reports (subscription required) and other publications because noise and rate of output are valued highly when it comes to quantitative testing. But these same traits that benefit ultrasonic humidifiers in lab testing can actually lead to problems in the real world.
Ultrasonic humidifiers rely on a vibrating diaphragm to generate vapor independent of the surrounding relative humidity, which is why they’re so fast. But if you’re not using distilled water (which gets expensive very quickly), or if the included demineralization treatments prove to be ineffective (a common complaint), this can cause a fine white mineral dust to settle all over the surrounding area, which is no good.
And while fast humidification is a good thing for a dry house, if your house is already comfortably humidified because you’ve been running the machine for a while, continuing to humidify will lead to over-humidification very quickly. This can cause issues with mold growth and other undesirable side effects.
Some models include humidistats to prevent this, but these are hardly foolproof. Indeed, many of the humidistat-equipped machines we have tested failed to provide accurate readings—discrepancies as large as 43 percent were observed for the Sunpentown SU-3600 and greater than 10 percent for the highly touted Air-O-Swiss 7135. Also, if there’s no water in the tank to absorb the vibrations, the machine can actually break itself—which is why we looked only at ultrasonic models that had an auto-off feature.
Finally, if you forget to clean, whatever’s growing in the reservoir will also be vaporized and enter your house’s air. Overall, these are substantial downsides that lab testing fails to account for, and they led us to look more deeply into competing technologies this time around.
Previously, we had written off evaporative humidifiers because they are louder and slower to humidify a space than their ultrasonic counterparts, but readers (rightly) called us out for not giving more weight to the upsides of evaporative technology.
Evaporative humidifiers utilize the natural process of evaporation to add moisture to the air. Dry air is drawn in and passed through a wet wicking filter, and humidified air is blown out into the room by a fan. They do make more noise than some due to the fan, but it’s not objectionable—far less than, say, an air conditioner or air purifier. The evaporative process is also slower than the vaporization process used by ultrasonic models, but it has the big advantage of automatically preventing over-humidification: The evaporative process slows as the air gets wetter. And while high output is desirable at first, continuously running your humidifier is really not necessary for simply maintaining an already comfortable level of humidity.
Evaporative models are also among the cleanest because any minerals are left behind, trapped in the wicking filter. The wick filters do need to be replaced, or at least cleaned, every one to three months, but if you wait a bit too long, the penalties are trivial—basically just reduced efficiency (no white dust, no vaporized bacteria). Over time, the cost of wick filters (about $12 each) is comparable to the cost of demineralization filters, but the initial purchase price tends to be lower. You can buy a decent evaporative model for about $50, whereas quality ultrasonic models start around $70.
A third technology worth considering is referred to as “air-washing” by marketing materials, but it’s really just a variation on evaporative humidification. The difference is that instead of a stationary wick, they have a stack of very slowly rotating discs. A fan draws air into the unit, then across the wet discs where (in theory) particles are trapped in the water and humidified air is blown out. These are quieter than evaporative models but also very expensive—a midsize model starts around $250.
The other technologies are warm-mist and impeller. Warm-mist humidifiers work by heating water into steam. As you might guess, this is not terribly efficient and poses a burn hazard for children (and forgetful adults). However, some people like the warmth that they aid to the air. Impeller models use a rapidly spinning disk to fling water against a diffuser plate that breaks the droplets into fine mist. They are quiet, but like the ultrasonic models can produce a white dust. The moisture output is low so they are best for small rooms (approximately ½ gallon per day versus two gallons per day for midsize models). Based on their generally abysmal user ratings on Amazon and their very low output, we skipped impeller humidifiers entirely.
With that in mind, we built a list of potential models to test—as of our latest test, it now runs to 61 different humidifiers. Narrowing that down based on user reviews, cost considerations, and other factors has led us, as of November 2015, to thoroughly test 16 of the most promising:
- The Honeywell HCM-350 (700 square feet of coverage) The best-selling humidifier on Amazon has 4.1 stars across 599 reviewers; after two rounds of testing, it’s still our pick.
- The Sunpentown SU-9210 (450 square feet) is recommended by Consumer Reports. The cheapest model to include a humidistat, it’s our runner-up humidifier.
- The Vornado Evap3 (700 square feet) has an elegant design (for a humidifier) and four-star Amazon rating from more than 400 reviews. Vornado claims that its “vortex circulation technology” gives its humidifiers a performance edge.
- The Vornado Evap2 (600 square feet) is a smaller version of the Evap3. It has lower and fewer ratings on Amazon (3.5 stars, 61 reviews), but we wanted to test this model for smaller spaces.
- The Sunpentown SU-4010 (500 square feet) is recommended by Consumer Reports and Consumer Search and has 3.6 Amazon stars across 655 reviews.
- The Air-O-Swiss 7135 (650 square feet) is a former Sweethome pick and highly regarded by Consumer Reports and other online publications.
- The Safety 1st Ultrasonic 360 Humidifier (215 square feet) Very simple, yet effective for rooms less than 300 square feet. Amazon users give it 3.7 stars over 742 reviews.
- The Stadler Form Hera (600 square feet) Highly rated (4.5 stars) by Allergy Buyer’s Club, it has a large two-gallon reservoir and good feature set, including a humidistat, demineralization cartridge, silver antimicrobial cube, and night mode.
- The Ivation IVADIGHUM678W is brought to you by C&A Marketing, the team behind SkyMall. A sharp looking model, it’s highly rated on Amazon, though only by a handful of owners.
- The Optimus Coolmist Ultrasonic Humidifier is a well-reviewed, bare-bones ultrasonic model.
- Dyson’s AM10 is a uniquely shaped ultrasonic humidifier that builds on their earlier fan models. We wondered what you might get for spending as much as possible for a humidifier.
- The Venta LW25 Airwasher (400 square feet) is a compact unit with huge two-gallon reservoir and very quiet fan; it’s our upgrade pick.
- The Winix FreshHome Air Washers AW107 (600 square feet) is highly rated by Top Ten Reviews. The plasmawave feature claims to purify air, but we found it to emit an irritating high-pitched noise. Unfortunately, there is no switch for this feature.
- The Vicks Warm Mist V750 (450 square feet) is highly rated by owners on Amazon. It’s our pick in the category.
- The Stadler Form Fred (500 square feet) has a controversial design. It’s either sleek and modern, or an ugly alien saucer, or a mini charcoal grill. It gets decent reviews, but it also gets alarmingly hot.
- The Honeywell HWM705B (450 square feet) is nearly identical to the Vicks; both are made by KAZ. But it performed markedly less well in our tests, and the outside gets warm.
For the testing process, we wanted to develop a series of questions that could be objectively addressed: humidifying ability, rate of water usage, noise level, power consumption, cost of consumables (wicks, demineralization treatments, specialized cleaning supplies). Results from these tests were combined with subjective considerations such as ease of use, filling, cleaning, simplicity of controls, durability, and overall fit and finish. We cover our methods and results in greater detail in the How we tested section later on.
Based on the results of our objective testing, plus ease of handling, consumer reviews, and a preference toward simplicity, both of the evaporative models float to the top of the heap. They have advantages of never over-humidifying and never producing a white dust, whereas users of ultrasonic models have reported seeing dust, even with demineralization cartridges. Among these two, the Honeywell had a slight edge in usability and design. After deciding on this, Sweethome editors Harry Sawyers and Ganda Suthivarakom bought the Honeywell and provided us with their own (positive) feedback.
The Honeywell HCM-350 is affordable, and it performed consistently well across all categories we tested. While it didn’t top the charts, it was a solid performer, raising the relative humidity of my office by 14 percentage points over the course of three hours. More important, among our entire test batch, it was the easiest to clean and fill, which are the two things you’ll be doing most often with any humidifier. Regular cleaning is crucial for optimal humidifier efficacy and keeping your environment healthy, so the fact that this unit makes it easy means that you’ll get better performance in the long run.
The Honeywell HCM-350’s ease of use and cleaning is the result of very deliberate design decisions on the part of the manufacturer that avoid the pain points common in other competing models. The best example of this is that all parts that touch water in the Honeywell (and are thus liable to accumulate bacterial/algal/fungal growth) contain no electronic parts and are completely submersible in water for easy washing. The reservoir and water tray are even dishwasher safe (top rack only, no detergent; the reservoir is quite tall, so most will not be able to set it upright on the top rack). This is how it should be. Yet the HCM-350 stands in stark contrast to many models, like our former Air-O-Swiss 7135 pick, which contain electronics in the base that require you to clean it by hand.
Our senior editor Harry Sawyers has owned several disappointing humidifiers in the past. He was particularly appreciative of the HCM-350’s tray. He calls it a huge improvement over the typical humidifier’s base unit, which has “a million nooks and crannies to clean—and a cord coming off of it.”
Our pick’s bottom tray, however, has no cords coming off of it and no nooks, so a simple sponge or scrubber is all that’s necessary to give it a thorough, manual cleaning. If necessary, it can be totally immersed without damaging the electronics or cleaned in the top rack of the dishwasher. Compare that to our ultrasonic pick, the Sunpentown SU-4010, which Sawyers also owns; he has to “get in there with a vinegar-soaked toothbrush” to clean.
The reservoir is also fairly easy to clean thanks to a huge filling hole that you can easily stick your arm into if need be. Compare that with the Safety 1st’s tiny 1¾-inch-diameter fill hole, which is only big enough for two fingers, or the Sunpentown SU-4010, which can fit a hand, but not an arm. For the most part, simply filling with warm soapy water and giving this tank a good shake should suffice. You can place the tank in the top rack of the dishwasher, but most people will only be able to fit it in sideways, which doesn’t allow you to disinfect the inside of the tank. Since that part of the tank generally gets filled and emptied with tap water regularly, it shouldn’t get too dirty.
Another aspect we like about the reservoir is that it is the easiest to fill. Sure, its one-gallon size means you’re going to have to fill it more often (about twice a day if you’re running it on high for 24 hours), but it fits under an average bathroom sink just fine (confirmed by all three testers). The tank’s thick, molded handle will support it while filling, so you don’t need to hold the tank in place, a feature greatly appreciated by Sweethome’s executive editor Ganda Suthivarakom. Sawyers liked that it barely dripped at all when lifted from its base. The handle also provides comfortable transportation that all testers appreciated—especially useful when loaded up with liquid.
Not only is the reservoir easy to fill and carry, it’s more durable than other models’ as well because it’s blow-molded from a single, continuous piece of plastic (like a milk jug). This is better than the two-piece (or more) fused-plastic designs found on many other models. The one-piece design is much less likely to develop leaks over time because it doesn’t have any seams that can come apart. This means it will likely outlast its three-year warranty, which is already generous compared to most models’ one-year warranties.
Once you’ve filled the HCM-350’s reservoir, closing it is as easy as screwing the cap on tightly, dropping it into the base, and turning the three-fan speed rotary switch to the desired setting and putting it somewhere out of the way for the next 12 to 24 hours (depending on which setting you use)—compare that with the Air-O-Swiss 7135’s six-button, pictorial UI.
With evaporative humidifiers, you’ll never encounter problems with white dust.
But, of course, none of this would matter if the HCM-350 didn’t also perform well in testing. While it never topped the charts, it performed consistently well in all measurable categories. In our initial series of tests, it was able to raise the relative humidity of my 160-square-foot office with standard eight-foot ceilings by 14 percent (from 50 to 64 percent) over the course of our three-hour testing period.
This was right in line with the other machines of similar size and only significantly less effective than the Air-O-Swiss, which raised relative humidity by a whopping 34 percent (though it formed a massive puddle on the floor in doing so). However, it’s worth noting that evaporative humidifiers tend to underperform in already wet conditions since dry air sucks up moisture at a faster rate than humid air. We tried everything we could to lower the starting relative humidity for our scheduled testing day (bringing in multiple dehumidifiers, an air conditioner, and a space heater), but we were unsuccessful.
After an initial delay of several days of uncooperative weather, we had to make do with the best we could to get this guide done in a timely manner. But just to make sure, we conducted another test on a much later, drier day in a slightly smaller room (120 square feet). Under these conditions, the Honeywell was able to raise humidity from 22 percent to 64.5 percent in the same three-hour period, so it’s definitely a capable machine. It’s rated to “medium-size rooms,” which Honeywell defines as 500 to 800 square feet, which might be a bit optimistic—Sawyers felt a decrease in relative humidity compared with previous ultrasonic models he’s used in his rather large bedroom (about 400 square feet), but added that he thought the easy cleaning was an attractive tradeoff.
As far as water output goes, we measured it at about 1.9 gallons per day on high, which is a bit lower than the 2.3 gallons Honeywell claims (as was the case with most of the other models we tested) but in line with most midsize humidifiers. That means you’ll have to fill it twice a day to keep it running 24 hours on drier days.
The HCM-350 is not virtually silent, like the ultrasonic models we tested, but it is still very quiet. We measured its sound level at 48.9 dB(A) from a distance of one meter using our sound meter app; this is loud enough that you’ll notice it, but not objectionable since it’s well under the 55 dB(A) it takes to begin interfering with a typical conversation. The level drops down to a barely noticeable 40.3 dB(A) if you set the fan speed to medium.
More important than sound pressure levels, though, the tone and pitch of the noise isn’t piercing or annoying in any way. Rather, it’s a pleasant white noise that sounds like a box fan on a medium to low setting. Suthivarakom, who is used to a warm-mist humidifier, said, “It’s really, really quiet.” Sawyers said, “It got a pretty good hum going on high, but it sounded like the white noise machines we bought for the boys’ rooms, so it’s not unpleasant.”
Including purchase price, cost of consumables, and electricity, it’ll set you back about $300 over the course of its three-year expected service life (assuming you’re running it 24 hours a day, but only in the winter time). That puts it right in the middle of the pack; total estimated costs for the models we tested range from around $85 for the budget-oriented Safety 1st to over $550 for the Air-O-Swiss, which suffers from expensive demineralization treatments. However, the Honeywell’s roughly-$50 initial purchase price was the second-lowest among all the machines we tested, which makes it an appealing value up front.
*At the time of publishing, the price was $10.
Replacement filters are a simple drop-in affair. Depending on the hardness of your water, Honeywell recommends replacing the filters every one to three months, though Amazon reviewer Samantha found they lasted six to seven months with regular washing. No tools are needed for installation. It’s normal for the filters to turn brown as the mineral deposits build up, and you can extend the life of the filter by flipping it top to bottom every time you refill the tank or rinse out the base. Once the filter becomes stiff and saturated with minerals, the wicking ability is impeded, so you will notice a drop-off in humidifying ability (and water consumption). So if you notice that there’s more water left in the tank than expected when you go to refill it, it’s probably time to replace or clean the filter.
Who else likes it?
The HCM-350 is well reviewed at Consumer Reports. It just missed the recommended cut (a rating of 73 versus a high of 86), and CR said humidity output, energy efficiency, and convenience were all great. The publication had some issues with the HCM-350 that we don’t really agree with (and will cover in the next section).
Top Ten Reviews was also fairly impressed, giving it a score of 8.1/10. They liked its long three-year warranty and the fact that it was silent, but did not like that it humidified at a slower rate than ultrasonic competitors. Their review concludes, “Although this unit is slightly larger than humidifiers of similar coverage, it offers safe cool mist and effective relief from the dry air in your home.”
It has also been among Amazon’s best-selling humidifiers for quite some time (well over a year, as of November 2015), which was our initial reason for calling it in. In addition to being popular, it carries an exceptionally high 4.0-star average for a humidifier (most fall in the 3-to-3.7-star range). Reviewers switching from ultrasonic models note that the lack of white dust is a major benefit and praise its ease of use. The well-designed reservoir was a major positive for Amazon reviewer Tes, who writes in her five-star review titled “Best humidifier in 30 years:” “The handle design is the most comfortable and well balanced of any humidifier I’ve ever owned so trips to and from the sink aren’t so awkward. The lid is extremely easy to get off/on and my husband never overtightens this one. The fill tank opening is not only easy to get into but very large so a gushing flow from the tub can fill it up very quickly.”
Flaws but not dealbreakers
The evaporative Honeywell is about as effective as any machine at maintaining a comfortable level of relative humidity, but it takes a bit longer to to get to that comfortable level than its ultrasonic competitors. This means it’s good to give it a bit of a head start before bedtime if you’re not planning on running it 24 hours a day. Sawyers initially reported that turning it on right before bed was not delivering as much humidity as he was used to with the ultrasonic Sunpentown 4010, but after giving it a couple hours’ head start, the air felt much better, though not quite as good as it did when using the Sunpentown. That being said, Sawyers has a rather large bedroom (about 400 square feet) and also said that the easy cleaning was an attractive enough tradeoff to keep him from switching back to the ultrasonic model.
The biggest flaw is probably the one-gallon reservoir, which needs refilling at least once a day compared with the larger ones found in the Air-O-Swiss 7135 (1.7 gallons) and Venta LW25 (2.0 gallons). At the same time, a larger reservoir carries its own drawbacks. They can be more difficult to clean, harder to fit under smaller sinks, and heavier when filled. You win some and lose some.
The most common complaint from Amazon reviews is from mold growing on the filter, but this is a problem with evaporative wicks in general and is not unique to the HCM-350. This can be avoided in a few ways. First off, you could let it run on empty so that the filter dries out. Or you could try alternating filters. Pull one out and let it dry completely, then swap again the next day.
There’s also no humidistat for this model, but as we previously covered, this isn’t as big of a concern for evaporative models because they are physically incapable of over-humidifying. If you’re really concerned, just run it on medium or low and you’ll be fine. Besides, out of the models we tested that did have humidistats, only half of them were accurate, so it’s not a terribly reliable feature anyway.
In January 2016 we investigated several complaints from readers about replacement filters for our humidifier pick, the Honeywell HCM-350. The complaints included poor fit; that the replacements were thinner than the originals; looked different; and/or did not perform satisfactorily. We spoke at length with a representative of Kaz, the manufacturer of the HCM-350. In addition to answering our questions, the representative sent photographs and a physical sample of the current-issue replacement filter. We also independently ordered a replacement filter from Amazon to be sure we were getting the same model that our readers would. Finally, we compared the original filter in our test model to the replacement filters. Here’s what we learned.
- Kaz, the manufacturer of the Honeywell humidifier, switched from a 1.5-inch-thick filter to a .75-inch-thick filter around 2011. If anyone recently received a humidifier with a 1.5-inch-thick filter, it was (very) old stock.
- Kaz phased out the outer blue “Airwash” layer on the filters in 2014. The Airwash filter was found to reduce the humidifier’s output. Other than this change, the filters are identical.
- The replacement filters that Kaz sent us, the replacement we got from Amazon, and the original that we pulled out of our test model are all identical except for the Airwash layer or lack of one. The replacements we got from Kaz and from Amazon both fit our HCM-350 humidifier perfectly.
- Kaz may have helped create confusion by selling the same replacement filter under two different names: Filter A and HAC-504. Both names refer to same product. HAC-504AW and HAC-504OS appear to be terms used by third-party sellers to refer to “Airwash” or “Old Stock” filters that have the blue Airwash layer. Few if any of them should be available anymore. To be absolutely certain you are getting a genuine Honeywell Filter A/HAC-504, you can order directly from the manufacturer.
- We’ve been using our test HCM-350 for two years now and at least three Sweethome/Wirecutter editors use one to their satisfaction in their own homes. We have never had a problem with their performance, their filters, or with mold.
Given all this, we stand behind our pick of the HCM-350 without reservation.
Then, there’s the matter of the germ-killing UV bulb, which you’ll note has hardly been mentioned by us, despite it being prominently featured in the marketing materials. Honeywell refers to an “independent report” that tested UV light as being 99.9 percent effective in killing E. coli and other germs after two hours of exposure. Given the slow rate at which water flows through this machine, it’s certainly possible that the bulb is effective at reducing the amount of funk that reaches the filter. Yet at the same time, it’s not clear that the UV lamp is really effective or well positioned. It only illuminates a small portion of the water as it flows from the tank over to the filter wick.
That being said, some users are extremely upset by the fact that replacement bulbs are expensive and must be obtained by either phone or snail mail directly from the manufacturer. We are sympathetic to their indignation in principle because if a company is selling a product that needs replacement parts that are designed to wear out, said parts should be widely available online and/or in store. However, considering that the feature is of dubious efficacy in the first place, and the HCM-350 is still cheaper than many units that don’t have UV lamps, we think it’s better to just pretend that the HCM-350 doesn’t have this feature at all. An indicator light changes from green to red when it’s time to replace the UV lamp. Frankly, we wouldn’t bother replacing it after the first one burns out after about 3,000 hours, or about four months of daily, around-the-clock use. (But if you must replace it, see this footnote for instructions on how to do so.4)
As previously mentioned, in their review Consumer Reports lists a number of cons to this unit, but we don’t think their quibbles hold up to close scrutiny. For example, Consumer Reports dinged the HCM-350 for hard-water performance, which is the percentage of hard tap water put into the machine that is turned into humidity, but this is actually a good thing. Those minerals are what cause the white dust issue and are a potential health hazard as well—you don’t want them in the air. They also dinged the HCM-350 for the lack of indicator when the tank is empty, but the tank is clear and it’s pretty straightforward to fill it every night before bed (and again in the morning if you want to run it all day).
CR also notes that there’s no auto shut-off when the tank is empty, but that is not a major issue with evaporative models because unlike ultrasonic models, running an evaporative humidifier on empty won’t break the machine. Indeed, if you intend to let it sit dry for any extended period of time, it’s good to let it run when empty for a while to dry the wick so it doesn’t mold. True, it would be best to lower the fan speed to save energy while drying off the the filter, then shut off when that’s done. But since it uses only 44 watts on high, it’s not a big deal.
Finally, it’s worth noting that with pretty much every non-warm-mist humidifier, running it can make you feel a bit cooler even if it’s not. The actual temperature does not drop according to a thermometer, but Suthivarakom found herself reaching for an extra blanket at night and you might, too.
If the Honeywell goes out of stock, the SPT SU-9210 is another evaporative humidifier we liked in testing. As an evaporative humidifier, the SU-9210 has all the same inherent benefits over ultrasonic models as the Honeywell: lack of white dust and general inability to over-humidify. But it’s not nearly as easy to clean as our top pick (though nothing really is), which ultimately makes it more difficult to live with.
Still, it has a number of useful features that some people might appreciate, including an accurate humidistat for peace of mind and a timer mode, which lets it run from one to 10 hours. Consumer Reports also likes it, giving it a recommendation and a score of 79 versus the Honeywell’s 76.
As far as quantitative testing goes, the SPT SU-9210 kept right up with the Honeywell. Its 47.8 dB(A) sound level was right in line with the Honeywell’s 48.9 dB(A) reading, and it increased relative humidity by 19.75 percent in our initial testing setup (compared with the Honeywell’s 14 percent—though the Honeywell started at a higher humidity). When we tested the humidistat’s ability to accurately maintain a RH of 65 percent, it held steady from 62 to 64 percent, which beat out models costing more than twice as much. Speaking of economics, the SU-9210’s total estimated operating cost of about $200 makes it slightly cheaper than the Honeywell over the course of three years (wicks are two for about $20).
Ultimately, the Honeywell provides a better overall user experience. While the Honeywell is specifically designed to be easy to clean, the Sunpentown has many of the typical humidifier design flaws. The hand-wash-only reservoir is made of several plastic pieces fused together, and I’d worry about these leaking over time. On the plus side, the base and reservoir separate from the fan casing (where the electrical bits are) for easy cleaning. But what bothered me most about this model are beeps upon every button push, which is completely unnecessary and irritating.
It is a little over half the size of the Honeywell, measuring in at 9 by 14 by 11 inches and weighing a comparatively light 5.6 pounds, but we’d rather have a larger humidifier that’s easier to clean and less annoying. Overall, the SU-9210 is a good unit, but the Honeywell is better.
For larger rooms: a silent ultrasonic pick
The Sunpentown SPT SU-4010 was our previous runner-up pick and is still a solid and economical performer containing a demineralization cartridge. If you have a larger room (bigger than, say, 400 square feet) and value moisture over ease of maintenance, this is your best bet. Sawyers found it more effective than the Honeywell in a large bedroom. But he offers this warning: “You can potentially have over-humidification with the Sunpentown—it’s like a powerful vehicle that you can drive recklessly if you lay on the throttle.”
Consumer Reports gave it a Best Buy rating at 86/100. It’s super quiet, even for an ultrasonic humidifier, and has an ion exchange water filter (a filter that draws the calcium and magnesium ions in your water in and then replaces them with sodium ions) to help keep microbial growth and mineral dust to a minimum. The dual mist spouts can be aimed toward the part of the room you want the humidity to hit (or they can be aimed away from things that should stay dry, like, say, a lampshade). Additionally, its tall, thin design (13 by 12 by 5 inches, 7.5 pounds) makes it a good choice for anyone short on table space. It’s also, for what it’s worth, quite pleasant to look at.
The main flaws on this unit are those daily tasks that hold back several humidifiers—cleaning and refilling. The base of the unit has the electronics attached, and mildew tends to build up along several sharp angles inside. This is the one Sawyers had to clean with the vinegar-soaked toothbrush, because total immersion of the base is impossible. The misting spouts tend to dribble water when they’re removed from the tank from refilling. And it’s usually impossible to get the tank from the bathroom back to the bedroom without losing a few drops of water to the floor along the way. That happens even if you overtighten the tank lid, which is too easy to do.
“The flaws in this one seemed fine to me at the time, because it was a step up from our older humidifier, the inexplicable Crane teardrop,” Sawyers said. “But now that I’ve used the Honeywell [our pick], it’s clear there’s a better option out there—for less money.”
The upgrade pick
The Venta Airwasher LW25 is worthy of its high price tag only if you are willing to pay a lot more money up front for lower power consumption and less-frequent cleanings, which can definitely be worth it for a lot of people. While your typical humidifier should be cleaned about every third day, Venta recommends cleaning only every 10 to 14 days and relies on a proprietary chemical mixture to keep funk down between cleanings. A two-week supply (3.5 ounces) is included with the LW25, and the bottle holds 35 ounces, so it’s good for more than four months of use. Additional bottles will run you about $20.
The Venta works by drawing air over a set of slowly rotating discs. It’s incredibly energy efficient, drawing seven watts on high, yet effective at humidifying, despite using only 0.2 gallons of water per day. That is not a typo. The LW25 literally uses an order of magnitude less water than the other midsize units we tested to achieve the same amount of humidification (18 percent increase over the three-hour test period).5 In very cold and dry climates, the daily output rate of water can be higher, up to about 1.5 gallons, according to a Venta PR representative.
We speculate that this might be due to the water additives you use with it: quaternary ammonium chlorides and a “water softening agent,” which increase the wet surface area for improved evaporation, disinfect, and reduce mineral buildup. However, despite this extreme efficiency, Venta still requires that you top it off every day in order to maintain maximum humidifying efficiency—it works best when full. (For what it’s worth, I tested it with the reservoir only two-thirds full and found that it was still effective, so it’s not the end of the world if you skip a day or two.)
It’s compact at 12 by 12 by 13 inches and 8.5 pounds, and it’s definitely a better choice than the other air washer we looked at made by Winix, which cost $20 more, had a more complicated user interface, and used 0.58 gallons per day, which is nearly three times as much as the Venta. The Winix also used an inferior disk design that required the disks to be inserted in only one way. The cover was similarly unidirectional. The Venta’s symmetric design avoids these drawbacks.
Despite its high sticker price and moderately high cost of the chemicals (about $40 per year), the overall price tag of the Venta spread out over a three-year operating life is relatively low. At about $425 total (sticker price plus maintenance costs), it’s the second most expensive, but an impossibly low electricity cost of just $15 makes it a lot more affordable than one would expect.
However, the Venta comes only with a two-year warranty, which is better than your typical one-year affair. Still, we’d like to see more from a unit of its cost.
As a final note on this machine, we were not impressed with its so-called “air washing” abilities. To test whether this machine was comparable to an actual air purifier, we used a laboratory-quality bench top optical particle counter that measured particles in the 0.5- to 20-micron range to measure airborne particle concentrations before and after three hours of testing. Background particle concentrations ranged from 65 to 200 particles per cubic centimeter. At the end of the testing period, the Venta lowered the particle concentration from a starting concentration of 180 particles per cubic centimeter to a final concentration of 9, which sounds impressive until you consider that the Honeywell, which makes no claims of air purification, got it down to 14 in a similar test (though the Winix air washer strangely did nothing to reduce particle counts). For reference, a HEPA-certified air purifier would bring this number down to virtually zero in less than half an hour.
If you must have warm mist
The Vicks Warm Mist V750 performed above average in our testing in the fall of 2015, raising the humidity levels from 60 to 82.5 percent over a three-hour period. It is clearly built to a price point, with cheap feeling plastic and wobbly assembly. But hey, it’s cheap. Compared to its sister model, the Honeywell HWM705B, it is slightly more solid and the outside got less hot.
The Vicks is compact (10½ inches by 12½ inches by 5¼ inches and a feathery 3½ pounds). It has a one-gallon tank with a comfortable handle and a mixing chamber that draws room air in to mix with the hot steam, so the moisture exiting is warm, not hot. There’s a medicine cup that allows you to add medications or essential oils. Operation is simple with a two-setting switch with an unobtrusive night light indicating water status: green during operation, and red when it has shut off after emptying the tank. We tested the humidifier on high (1.9 gallons per day), where the one gallon tank will need to be refilled every 12 hours. It features an auto shut off, (as do all steam models tested). It is a popular model on Amazon, with 3.9 stars and over 2,300 reviews. One note of concern are several reports of leaks occurring anywhere from a couple weeks to a year after purchase, but these are less than 10 percent of the reviews. Still, to be safe, you could place the humidifier on spacers inside a plastic tub to catch any leaks, in case they happen without warning.
Some general words of caution about warm mist
Warm-mist humidifiers work by heating water until it turns to steam. And that means they have the potential to cause burns—both from the hot water and steam and from the heating element. Because of that risk, the American Academy of Pediatrics recommends against their use in homes with children. (Note: the Stadler Form Fred, which we tested, was a particularly bad offender: Its silvery plastic steam-tube became extremely hot when the unit was on.)
People seem to like warm-mist humidifiers for four reasons: because they “work better,” because they “feel better,” because they can diffuse essential oils, and because the steaming process kills germs. Point one is simply untrue: Warm-mist humidifiers are no better or worse than other types at humidifying the air. Point two is subjective, but in our tests we noticed no difference in the feel of air humidified by the different methods. (Well, at extremely elevated humidity levels, above 70 percent, warm-mist air felt steamy and evaporative air felt a little clammy. But 70 percent is much higher than you’d ever get in your home.) Point three is true, but you don’t need a humidifier to diffuse essential oils; you just need a wick, a heater, and/or a fan. Point four may or may not be true (we haven’t found any research on the claim), but the fact is, domestic tap water is already pretty much germ-free, and as long as you clean it regularly, any humidifier will be perfectly hygienic.
Then there’s the matter of energy usage and cost. Warm-mist humidifiers slightly heat the room in which they are used, meaning the thermostat could be turned down a pinch. The other types of humidifier add water vapor to the air via evaporation, leading to a slight cooling of the air in the room, which will need to be heated again (via a furnace or other heating system).
The question is: do warm-mist humidifiers offset their energy costs by lowering your heating bill? To quantify this, I did a back of the envelope calculation using the following assumptions. The humidifier is used for three years (for six months each year) and dispenses four liters of water per day of use (just over one gallon). The house is heated with natural gas. For energy costs, I used my local California rates of 18 cents per kWh for electricity and $1.20 per therm for gas. The efficiency of both the electric humidifier (range 65 to 80 percent) and gas furnace was 80 percent (range 78 to 97 percent).
By figuring out the energy needed to heat the water from room temperature to near boiling (334 Joules), and adding the extra energy needed to vaporize it (2,260 Joules), we know the total energy (2,594 Joules) need per gram of water. Using the assumptions above, if you heat that water with the humidifier, you will spend a whopping $355 in electricity versus just $81 in natural gas to supply the same amount of heat to your air. That’s a $274 difference, and the difference could be even more if you have either a newer furnace or the humidifier is less than 80 percent efficient.
Humidifier care and maintenance
Regardless of which type of humidifier you have, you’re going to need to clean regularly to prevent funky stuff from growing in the reservoir and other parts of your humidifier. The US EPA suggests cleaning and disinfecting portable humidifiers every third day. Typically, water and elbow grease will get the job done, but you may need to use distilled white vinegar every so often to remove mineral deposits (scale).
Soap and other chemicals should generally be avoided because if you don’t thoroughly rinse it off, it’s going to get vaporized and you’ll end up breathing it. After the descaling step, rinse all surfaces with either one teaspoon of bleach mixed with a gallon of water or a three-percent hydrogen peroxide solution to disinfect and then wipe dry.
As previously touched upon, you will need to perform occasional wick maintenance on your evaporative humidifier. To clean an evaporative wick, soak it in cold water for 20 minutes and gently swish it back and forth to release minerals. Never use hot water or chemicals. To avoid mold growth on the filter, when you turn the humidifier off, pull out the filter and let it dry, or leave it in and let the fan run with no water until dry. But you can’t clean the same wick forever without the antimicrobial treatment wearing off, so you’re going to have to replace it every six months at a minimum (though this could be as often as every month if you have very hard water).
Ultrasonic humidifiers do not have wicks, but most do have some kind of demineralization cartridge or treatment that will need to be replaced every so often. Our Sunpentown ultrasonic pick has a $25 cartridge that they recommend swapping out every six months.
As for the air washers, Venta recommends refilling water daily in order to keep the reservoir nearly full, so the rotating disks will be fully saturated, meaning it will be more effective at humidifying. Every 10 to 14 days, drain and rinse the lower housing and disk stack with warm water, wipe housing and fan blade with a cloth, then fill and add another dose of 3½ ounces of their water treatment additive. Every six months, do a deep clean by filling the reservoir, adding their cleaner, and running on low for two hours, followed by rinsing with warm water per usual. To give the housing a thorough cleaning, disassemble the upper housing (no tools required) and wipe surfaces with a damp cloth.
How we tested
In 2014, testing was performed this fall in my 160-square-foot office with standard eight-foot ceilings. I live in Southern California in a 1960s house, typical of the era in that it is pretty leaky, compared with the tighter construction of new homes built with the newfangled concept of energy efficiency. We came up with the following questions:
Are any humidifiers too loud to live with?
With fridges, dishwashers, and other appliances all undergoing a “quiet” revolution, we wanted to test how loud our humidifiers were.
Sound pressure levels of each unit running on high and measured at a distance of one meter away and one half meter above the ground. Measurements were taken with an iPhone 5s running a NoiSee app, one of the top recommended apps in a survey of 192 apps by the National Institute for Occupational Safety and Health (NIOSH), where it came within +/-2 dB(A) of reference measurements. That’s plenty accurate for our purposes.
A noise level of 55 decibels, about the highest that would not interfere with normal conversation (60 decibels), was used as a limit. For reference, a quiet office is 40 decibels, moderate rainfall is 50 decibels, and normal conversation is around 60 decibels. In another category of appliances where noise is a concern—dishwashers—anything 50 decibels and below is considered to be in the “quietest” category, and any machine below 45 decibels is considered practically silent.
Two humidifiers failed this test. The worst offender was the Stadler Form Hera, which came in at a painfully loud 74 dB(A). We suspect it was a defective unit, as there is no reason for an ultrasonic humidifier to make this kind of racket. It was too loud to even continue with the remaining test, so it was out. The Vornado Evap2 came in at 59 dB(A) on high, but we kept it in the testing since it has an auto setting that adjusts the fan speed as necessary to maintain humidity.
Of the remaining humidifiers, we did not test the ultrasonic models with the sound pressure meter. They were all nearly silent, less than 40 dB(A), blending in well with the background noise (34 dB(A)).
How high can these humidifiers raise the humidity of a 160-square-foot room in three hours running on high?
This is a question we addressed in our previous guide, and going into the 2014 guide, we thought it was going to be one of the most important tests. If the humidifier can’t raise the humidity in a dry room, none of the other tests matter. The humidity depends strongly on the air temperature, and we wanted to hold this at a constant 20 +/- 1 degrees Celsius (68 +/- 1.8 degrees Fahrenheit). Since heated winter air can be as low as five to ten percent RH (relative humidity), and desired ranges are 30 to 50 percent, we wanted to start with the humidity as low as possible.
We tried everything we could to get to these conditions using three dehumidifiers, a 12,000-BTU portable A/C unit, and a portable 1,500-watt electric heater. (No, I don’t want to see my power bill.) Even with all these, we were unable to get to a stable starting condition of 20 degrees Celsius and 30 percent RH. So we settled for what we could get, which was running the tests near 22 degrees Celsius and about 50 percent RH for starters. (In 2015, using a slightly different setup, we achieved nearly identical conditions: stable at 23 degrees Celsius and about 50 percent RH.)
Using testing conditions of 22 C +/- 0.7 degrees, and average starting humidity 48.1 +/- 7.1 percent, humidifiers were filled with two liters of tap water and run for three hours on their highest setting. Temperature and humidity levels were measured every 15 seconds using two Lascar high-accuracy USB data loggers. They have a temperature accuracy of +/- 1 degree, and humidity accuracy of +/- 2 percent. One logger was placed one meter from the humidifier located on a one-meter stool near one wall, and the other was placed on a desk on the far side of the room. There was good agreement between the sensors, except for some of the ultrasonic humidifiers when the humidity near the unit would be five to 10 percent higher. For our purposes, the values were averaged.
The increase in humidity after three hours ranged from 14 to 34 percent, but was typically in the 15 to 20 percent range. The Air-O-Swiss 7135 had the biggest increase of 34 percent, but it made a sopping wet mess on the floor in the process. In a series of tests, Honeywell brought the humidity up 14 percent, from 50 to 64 percent. Another test in a slightly smaller room (120 square feet) saw it raise the humidity from 22 to 64.5 percent in three hours, so it’s definitely a capable machine.
We learned a lot from the test. First, all the units were effective at increasing the humidity, generally from a comfortable 50 percent to a moist 65 percent. This is higher than recommended, yet still pleasant. Second, we repeated the tests and found there was quite a bit of variability, even with basically the same starting conditions. Finally, the two evaporative units (the Honeywell and SU-9210) and two air washers top out the humidity at 60 to 65 percent, so there is little hazard of adding too much water to your room. All units were effective at raising the humidity, but the ultrasonic models have an ability to over-humidify and make a mess on the floor.
How well can the units with humidistats hold the humidity using a 65 percent RH set point?
The humidifiers with humidistats were evaluated to see how well they could hold the humidity steady at 65 percent. That’s higher than you’d need, but we wanted to push the envelope to see what they could do.
The SPT SU-9210 was the only unit capable of holding the humidity nearly constant, beginning at 62 percent and ending at 64 percent. The AOS 7135 did poorly, ramping the humidity from 50 percent way past 65 percent ending at 75 percent. The SPT SU3600 also failed, as the humidistat read a steady 33 percent and it sent the humidity soaring from 60 to 77 percent.
All the non-ultrasonic models were able to reach and hold humidities in the 60 to 65 percent range, even without a humidistat.
From this test, and a bit of research, we learned that humidity is a tricky measurement to make. The budget humidistats built into some humidifiers are not consistently up to the task. Even among humidistats from the same manufacturer, one worked (SU-9210) and one didn’t (SU-3600). The previous year’s Air-O-Swiss 7135 model had a humidistat that worked well and held the humidity within a couple of percent. In our current model of the AOS 7135, the humidistat was off by at least 12.5 percent.
What is the rate of water usage when all run at the same time (outside) compared to the manufacturer’s specification?
The units produced output rates between 1.1 and 2.4 gallons per day, about three-quarters of the manufacturer’s specification. We would expect the rate of output to be higher under extremely dry conditions. The Airwashers Venta and Winix were an exception in this test, outputting only 0.2 and 0.6 gallon per day, respectively. With an output rate that low for the Venta, we’d be worried about it having enough oomph, yet it performed well indoors, raising humidity levels 21.8 percent over three hours.
Comparison of the humidifiers daily output rate compared with manufacturers specification. From left to right, evaporative models (Honeywell and SU-9210), Ultrasonic models (SU-4010, Safety 1st, AOS 7135), and Airwasher models (Venta, Winix). The ultrasonic models as a group came closest to spec, followed by the evaporative models, which are more sensitive to ambient conditions. At very dry conditions, their rate of output will increase.
Are the “air washers” effective at removing particles?
For air washers, which claim to remove particles from the air, airborne particle concentrations were measured at the beginning of the test, and after three hours of running. We used a laboratory quality bench top optical particle counter that measured particles in the 0.5-to-20-micron range. Background particle concentrations ranged from 65 to 200 particles per cubic centimeter.
After running the Venta and Winix air washers and our top pick, the Honeywell HCM-350 evaporative humidifier, we saw the particle concentrations drop for the Venta and Honeywell, but rise for the Winix.
The Venta lowered the particle concentration from a starting concentration of 180 to a final 9 particles/cm3. Not nearly as clean as a stand-alone as the dedicated air purifiers tested for our best air purifier guide, but that’s still an order of magnitude reduction. However, the Honeywell, which isn’t marketed as an air washer, but still has air flowing through a wet filter, also saw the particle concentration change from 65 down to 14 particles per cubic centimeter, so we’re not prepared to tout this machine the Venta for its so-called air-washing abilities.
The Winix, however, didn’t reduce particle counts at all. They started at 70 and climbed to 150 particles/cm3 after three hours. Looking into these claims of air washing, I found that in 2008, Consumer Reports evaluated the Venta’s effectiveness in removing much smaller particles (0.1 to 3 microns) and found they were ineffective. Our take is that air washers and humidifiers can remove some larger particles (0.5 to 20 micron) like pollen and dust mites, but not nearly as well as a dedicated air purifier.
How much does it cost to operate over the lifetime of the machine (three years)?
The cost of ownership was calculated over an expected product lifetime of three years, running 24 hours a day, for six months a year. Power consumption of humidifiers was measured on the high setting using a Sperry DSA-500 clamp-on ammeter. The table below and calculations used for cost of ownership are based on the highest setting. Electricity rates are based on residential rates in my area of 0.15396 ($/kWh) and operation 24 hours a day. Consumables can include wick filters, demineralization cartridges, and antimicrobial silver cartridges.
Cost of ownership over expected three-year lifetime of humidifiers. Costs were calculated for seasonal usage, six months out of the year, over three years, for a total of 18 months.
If you must have a step down, the Safety 1st works, which is impressive for such a cheap unit, but its drawbacks keep it from being an official pick. It’s not a bad deal for about $30, but you’re going to get only that much worth of humidifier. It’s like buying a $3 bottle of wine. It can be good for $3, but that doesn’t mean it’s objectively good. As far as performance goes, the Safety 1st is an ultrasonic humidifier, so it runs very quietly and is capable of outputting a fair amount of moisture—it raised our test area’s relative humidity by 17.5 percent over our three-hour testing period. But it’s limited by a tiny 0.8-gallon reservoir that will need frequent refilling, and it lacks a mineral filter, which means you’ll have to use distilled water if you want to avoid mineral dust issues (which you do). Also, it has a two-piece reservoir with a small opening (making it hard to clean) and a long list of user reviews that complain about leaking and other problems—more than 25 percent of the 840 total reviews as of this writing are one- or two-star reviews.
The Air-O-Swiss 7135 was our previous top pick because of its silent operation, humidistat, and prodigious moisture output. Indeed, that it was able to raise an already-moist room’s relative humidity by 34 percent is quite impressive (though it did create a big puddle around the base in the process of doing so). Previously, we had put a lot of value into this humidifying ability, but based on feedback we’ve gotten, it’s more than most people need and more than most people want to pay. Its street price is already high. Add the highest cost of consumables (water treatments/demineralization cartridges) and electricity ($100 over three years) and you get the humidifier with the highest cost of ownership by far—even compared with the over-$300 Venta and Winix options. What’s more, the humidistat completely failed to maintain a consistent level of humidity in this round of testing.
The Winix Air Washer was effective at humidifying, but had no effect at removing particles and did little to justify its exorbitant price tag. While it uses the same basic technology as the Venta, the design made it more difficult to use. The base reservoir was not symmetric, and the set-up disks had to be inserted in the correct orientation. On the plus side, it doesn’t use any expensive, proprietary cleaning chemicals or water treatments. This leads to a lower overall cost of ownership. But you’d still have to clean the machine somehow using chemicals that won’t negatively affect your air quality. We think Venta’s approach is more user-friendly in this way because you know exactly what you need to get and how to use it. Sure, it costs more, but it’s money worth spending.
The SPT-SU3600 is Sunpentown’s newest humidifier, which crams a fairly capable machine into a compact, stylish package that would fit on most night stands. However, it’s a one step forward, two steps back situation. We liked the small size, and it’s nice that the one-gallon reservoir has a fill cap that seals in an eighth of a turn. But that’s offset by annoying touch-sensitive controls that offer no tactile feedback. You can’t tell what you are doing without looking. It also has a wildly inaccurate humidistat, which read 33 percent for the duration of a run designed to test its ability to hold the humidity constant at 65 percent. Instead of holding steady here, it pumped up the humidity to a muggy 77 percent and soaked the floor. And it’s missing a demineralization cartridge, so you’ll have white dust to contend with or the added cost of distilled water. If you prefer an ultrasonic model, you’d be better off skipping this one and going with the SU-4010, which has easier to use controls and a mineral filter.
The Stadler Form Hera is billed as a top-shelf unit, with an attractive feature set containing warm and cool mist ultrasonic mists with bi-directional nozzles, humidistat, and a night mode that automatically dims the display. Given the price tag, it really must deliver performance in order to justify the high cost. However, our unit generated excessive screeching noise measured at 74 dB! The humidifier put out mist, but was so loud that we aborted our tests. It’s well reviewed at Allergy Buyer’s Club, and I can’t imagine anyone tolerating this noise level, so perhaps our tester was defective. Amazon reviewer Matt states, “Maybe this humidifier provides more advanced features than other models, but since it doesn’t get the basics right it really doesn’t matter.” We have to agree.
The Stadler Form Fred steam humidifier has a controversial design. It’s either sleek and modern, or an ugly alien saucer / mini charcoal grill. It has a two-gallon reservoir that’s good for all day on high. Controls are simple to use, though quite small: a power button, high / low button, and rotary knob for moisture output. When assembling, your hand gets pinched when installing the reservoir, and the lid is slightly difficult to align. The vent gets very hot during operation, and points towards the back, so you can’t put it close to a wall. Finally, during testing, the output rate varied widely, from 1.0 to 1.9 gallons per day. We cannot recommend it, even if you love its looks.
The Honeywell HWM705B warm-mist humidifier is nearly identical to the Vicks. Both are made by KAZ. The Honeywell was more flimsy and the outside got hotter to the touch. Despite consuming the same amount of energy (~230 W), it only raised the RH 15.5 percent, from 55.5 to 71 percent, during our three-hour test. Only choose this model if you must have black.
The Ivation IVADIGHUM678W is brought to you by C&A Marketing, the team behind SkyMall. A sharp looking model with easy-to-use controls and a tremendous output (2.4 gallons per day). Unfortunately it lacks a demineralization cartridge and can’t control the humidity anywhere close to a setpoint—it soars off by over 20 percent. Lastly, it is no longer widely available.
The Optimus Coolmist Ultrasonic Humidifier is a well-reviewed, bare-bones ultrasonic model with simple dial control and strong two-gallon-per-day output. We found the output rate high, but extremely variable at 1.0 – 2.1 gallons per day (both on the high setting). The reservoir is a bit small at 1.11 gallons. It contains non-replaceable ceramic filters that will do little to trap minerals and prevent white dust.
Dyson’s AM10 is a uniquely shaped ultrasonic humidifier that builds on their earlier fan models. We wondered what you might get for spending as much as possible for a humidifier. The biggest difference from a basic ultrasonic model to one that costs much more is that it has a powerful fan to force the water droplets out through the oval opening. We found it solidly constructed and attractively designed and, well, different. Though not necessarily in a good way. For instance, you have to remove the oval portion before accessing the water reservoir. That’s an extra step. The fill hole for the tank is quite small, about the size of a quarter, making it more difficult to fill and harder to turn the knob to seal. Control is only possible via the remote, and the display is quite small and dimly lit. It performed well, ranking first on ability to hold relative humidity at a set point (average 1.4 percent RH over the set point, and 0.8 percent RH standard deviation), and third on humidity change (25.5 percent RH). Dyson definitely makes a statement with their design, but they fail to deliver value. Save your $500 to spend or invest elsewhere.
The Vornado Evap3 is a very attractive model. It aced the humidity-hold test, reaching the steadiest value among evaporative models, 3.6 percent over the set point and 1.0 percent standard deviation. It has a moderate 1½-gallon tank and high output of 2.7 gallons per day. It uses two wicking filters that last for 4 to 8 weeks before they need to be replaced, at a cost of $12. Operating modes are high, low, or auto, with a built in humidistat with values ranging from 35 to 60 percent RH, or continuous operation. Unfortunately, this model has a couple flaws. First, it’s a little bit loud on high (54 dB), just making our 55 dB cut-off. But the deal killer is that the fill cap is really hard to turn. The tabs are on the inside, similar to the cap of a cardboard poster tube. The best designs are those similar to the Honeywell HCM-350 and SPT SU-9210, which have a large diameter cap with a grippy circumference that you can wrap you hands around.
The Vornado Evap2 is a promising humidifier and the little version of the Evap3 model. It uses a single wicking filter. It also performed well on the humidity hold, coming in second among evaporative models. But it’s too loud (59 dB), and it’s too awkward to insert the reservoir. Aligning the base is tricky as it has to come in at an angle, and we found ourselves struggling each time we refilled.
What else we looked at
- Air-O-Swiss 7142 (860 square feet) Ultrasonic model, low 2.9 stars on Amazon. It’s highly rated when new at Top Ten Review and Allergy Buyers Club, but exceeds our 650-square-foot rating (860-square-foot), and it still has the same 3.5-gallon output as AOS 7135. Amazon reviewers report that failure over time, dying just after a year, poor customer service, inaccurate humidistat.
- Air-O-Swiss 7144 (650 square feet) Ultrasonic model, not very different from other AOS models, and smaller reservoir.
- Air-O-Swiss 7145 (540 square feet) Ultrasonic model, out of stock … discontinued and replaced by 7147.
- Air-O-Swiss 7147 (650 square feet) Ultrasonic model, smaller reservoir than 7135, not as efficient in previous Wirecutter tests.
- Bionaire 1 Gallon Warm and Cool Mist Ultrasonic Humidifier (N/A square feet) Ultrasonic model, not enough information to evaluate. Available at Best Buy, but sold out on Amazon. Not listed on Bionaire website as current product.
- Bionaire Ultrasonic Filter-Free Tower Humidifier (Medium-size room) Ultrasonic model, not much info to evaluate.
- Crane Cool Mist Humidifier (250 square feet) Ultrasonic model, During previous Wirecutter testing, the output was extremely low (0.5 gallons per day).
- Crane Cube 0.5 Gal. Ultrasonic Cool Mist Humidifier (250 square feet) Ultrasonic model, tiny ½-gallon reservoir.
- Crane Germ Defense EE-8064 (500 square feet) Ultrasonic model, Consumer Reports noted similar to EE-8065, but $40 more expensive.
- Crane Germ Defense EE-8065 (500 square feet) Ultrasonic model, decent unit recommended by Consumer Reports, but the indicator lights are super bright.
- Crane Owl (250 square feet) Ultrasonic model, too small, and while rated to 250 square feet, its output is only 1.4 gallons. Cute animals are not a good fit for everyone.
- Essick MA1201 (2,500 square feet) Evaporative model, whole-house unit that’s too big for most people, but excellent value.
- Holmes Smart Humidifier with WeMo (2,500 square feet) Evaporative model, whole house unit, much bigger model than we’re considering.
- HoMedics UHE-CM25 (100 square feet) Ultrasonic model, too small, only rated to 100 square feet.
- HoMedics UHE-CM45 (100 square feet) Ultrasonic model, too small, only rated to 100 square feet.
- Honeywell HCM-300T (1,050 square feet) Evaporative model, rated for bigger area that’s greater than 650 square feet.
- Honeywell HCM-6009 (1,900 square feet) Evaporative model, whole house console unit, much bigger than other models in this survey.
- Honeywell HCM-6011G Humidifier Quietcare Cool Mist Humidifier (2,300 square feet) Evaporative model, whole house unit. Too big.
- Honeywell HCM-631 (1,050 square feet) Evaporative model, rated for areas greater than 1,000 square feet, out of stock.
- Honeywell HUT-300 (400 square feet) Ultrasonic model, user reviews from Amazon indicate it is hard to clean, and the reservoir is small (0.8 gallon) reservoir.
- Honeywell HWM-340W (600 square feet) Vaporizer model, warm mist only, 400 watts to operate!
- Honeywell Mistmate (150 square feet) Ultrasonic model, too small, only rated to 150 square feet.
- Honeywell HWM 450 (1,400 square feet) Heated model, ruled out from negative Amazon reviews of unit burning itself out.
- Pure Guardian 0.2 Gal. Ultrasonic Cool Mist Humidifier (125 square feet) Ultrasonic model, too small, only rated to 125 square feet.
- Pure Guardian Elite 1.3 Gal. Ultrasonic Humidifier (300 square feet) Ultrasonic model, pricy for room size.
- Stadler Form William (1,000 square feet) Evaporative model, high cost and rated at more than 1,000 square feet.
- Vicks V3100 (small – medium) Evaporative model, 1.2 gallons per day too low an output.
- Vicks V5100NS (400 square feet) Ultrasonic model, top-rated Consumer Reports medium room size, but consistently poor Amazon reviews with multiple concerns of a noxious chemical smell and higher-than-normal dead on arrivals, 3 stars over 60 reviews. No longer available at Best Buy.
Wrapping it up
If you are troubled by symptoms (dry itchy skin, dry irritated sinuses, and cracked lips) caused by dry winter air or live in an especially dry climate, our picks are effective and easy to operate. Just stay on top of the daily filling and cleaning every three days to keep the mold and bacteria at bay. The Honeywell HCM-350 is a simple and durable humidifier that’s super easy to clean. If you’d prefer a nearly silent ultrasonic model, the SPT SU-4010 is a good pick. If you want low maintenance and a large reservoir, the Venta LW25 is what you need. Finally, if you want a warm-mist humidifier, we recommend the Vicks V750.
Humidifiers: Air moisture eases skin, breathing symptoms, Mayo Clinic, May 18, 2013
Humidifier buying guide, Consumer Reports, December 2015
Humidifier Buying Guide, iAllergy, 2015
Humidifiers Buying Guide, Canadian Tire
Originally published: December 7, 2015