There are ultrasonic humidifiers, at the same price point, that have humidity meters built in so they don't over humidify. It's completely dishonest for wirecutter to claim that the entire category over-humidifies. It's just not true.
Ultrasonic just sprays all the disolved minerals across your room. You won't notice it at first, but about 2 or 3 weeks into using the device, you'll find plenty of "white dust" all over your room.
In my experience, you get a smelly bacteria-infested humidifier if you keep using it for a few days. You need to regularly rinse ultrasonic humidifiers... or really any humidifier at all.
So, I have one of these running in my room right now (and have for the whole winter thus far). No white dust. That said, I don't run it at full power, I keep it where I can barely see any mist coming out.
It humidifies the room quite nicely, keeping it at about 40% humidity (our house averages 25% without humidifiers running, which is hell on skin and noses).
Maybe my tap water has more minerals than your tap water. A good bit of slag builds up in my warm-air humidifier, and the white-dust was noticeable after a few weeks of ultrasonic.
Warm-air humidifiers are less efficient: My room is ~25% without any devices running. An ultrasonic would bring it up to 35%+, but Warm-air humidifier only brings it up to 32% or so.
Another efficiency test: both units were 1-quart (EDIT: Not a gallon) units. The warm-air humidifier probably goes through the tank in ~12 hours, while the ultrasonic would go through in ~8.
> Maybe my tap water has more minerals than your tap water
Unlikely; my tap water is well water. I do clean the humidifier with vinegar every week to keep the mineral buildup down. Then again, I do that with the shower head and tea kettle too (though a bit less frequently).
The big thing, as I've found it, is keeping the output down to a visible minimum. A big plume of mist that visibly lands anywhere isn't adding more water to the air - it's putting water droplets on the surface much like a spray bottle. It looks good, but isn't doing the job you're asking it to.
Then it is probably a difference in ultrasonic humidifiers. I can tell you that mine barely builds up much slag at all. I switched to warm-air after I grew tired of the white-dust issue.
The white-dust issue is further confirmed as I use the warm-air (boiling-type) humidifier. A LOT of minerals are found every day from my boiled-away tap-water... minerals that clearly used to be sprayed into the air and dusting my furniture.
It's expensive, but distilled water will fix that. Cheaper is filling it up from an RO filter (not as low in minerals as distilled, but probably "good enough")
I definitely think they need to revise that copy. The article actually has a recommendation now for an ultrasonic with an accurate hygrometer that wasn't there when I first read the article ~9 years ago.
