Humidifiers: Simpler is better?
This video certainly won’t be very… dry. [ oof ] I’ve had a bit of an epiphany in recent days. See, over the summer I made a video about this stupid thing. You can check it out if you like (links are in all the places) but as a quick recap, this is what purports to be a "personal air conditioner" but in fact it's a teeny tiny evaporative cooler, also known as a swamp cooler.
And that’s why they’re, well, silly! Unless you live in a really arid place, adding moisture to the air is exactly the wrong way to achieve cooling. These things are by and large a waste of headspace, desk pace, and plastic. Just… don’t. Fast forward to a few weeks ago.
Winter’s rearing its ugly head here in the midwest which means the air’s getting uncomfortably dry. I ventured out to the exotic lands of Walmart to buy a cheap humidifier for my bedroom. In fact, this one! Now, it claims to emit “invisible cool mist” which, ok.
Sure. I went to set it up and, lo and behold, the thing’s just a swamp cooler. This is, almost uncannily, the exact same device as the personal cooler, save for a much larger water tank and fan. Huh. Yep, this thing is almost stupidly simple and I love it.
There are three basic parts: the water tank, the body which contains the fan, and the water absorbing matrix. A plastic base provides support for the three parts to come together. The matrix, which Equate calls a filter but that’s... a silly name, sits in a shallow pool of water and capillary action causes that water to travel up the material and soak the entire thing. This wicking action is why more sensible humidifier manufacturers call this… John. Sorry, the wick.
In operation, the fan pulls air through the damp wick. The large surface area of the wick helps the water it holds evaporate into the air more quickly, and the fan makes this go even quicklier by constantly moving air through it. As the water evaporates, the wick continues to absorb more water.
The water tank allows for continuous operation by constantly replenishing the pool of water and keeping it at a consistent height, at least until it runs out. Its shape contains a void for the wick, and the tank’s carrying handle then becomes the air intake. Quite clever! That said, this isn’t a very good humidifier. It just isn’t capable of much output: it takes about two days running at its high setting to go through the entire tank contrary to its “up to 24 hour” runtime.
That makes it appropriate for small rooms, but not much else. In fairness, they did say that on the box. Now, I wanted to get something larger - something capable of humidifying my entire home. And it turns out that most whole-house humidifiers use the same concept as this one, but scaled up. Through them, I’ve apparently discovered one of those cases where the simplest idea is the most effective.
Let’s back up a minute. Why do I want a humidifier in the first place? Many of you across the world probably think that wanting to add moisture to the air is insane. You probably live some place where it’s hot and humid. Fun fact! It’s hot and humid here, too! In the summer… yeah we get the worst of both worlds. It’s great!
In the winter, though, nature conspires against us and makes the air often unbearably dry. See, when we talk about humidity we almost always talk in terms of relative humidity. It’s expressed as a percentage, indicating how much moisture is in the air compared to air’s ability to hold moisture.
When relative humidity is 50%, the air is therefore holding half of the water that it can. It’s 50% moist. When it’s 100%, the air is fully saturated and can no longer take on any moisture. We use relative humidity because it correlates with how our bodies and in fact pretty much everything “feels” humidity. But, and here’s where nature sneaks up on ya, the ability for air to hold moisture varies with its temperature. Warm air can hold more moisture than cold air: at 20 degrees Celsius, or 68 Fahrenheit 1 kilogram of air can hold approximately 15 grams of water vapor.
At zero degrees Celsius, or 32 Fahrenheit, it can only hold about 5 grams - roughly a third. That means that at the same relative humidity, say 50%, the air outside can only hold a third of the moisture that the air in your home can. Now, because the air in your home is ultimately the same air as outside, you’re at the mercy of how humid the outdoor air is. And when you heat that air up to make a living space more comfortable, you increase its ability to hold moisture, but not the actual amount of moisture it contains. This makes relative humidity plummet.
At freezing point, even if the air outside is at 100% humidity, when you warm it to a comfortable indoor air temperature now the relative humidity is just 33%. It didn’t lose any moisture, it’s just able to hold more and that makes it feel dryer. This gets worse the colder it becomes outside. Since where I live it’s not uncommon for the outdoor temperature to be between zero and 10 degrees Fahrenheit (that’s about -18 to -12 Celsius) indoor air can sometimes be desert-levels of dry. This is obviously uncomfortable, leads to things like peeling skin and chapped lips, often makes your throat scratchy, it makes static shocks happen all the dang time, and seems to be a contributing factor to viral spread, although we don’t quite understand why yet. One hypothesis is that dryer air allows airborne droplets containing virus particles to remain suspended for longer since those droplets dry out quickly and remain afloat more easily with less mass, but that’s just one explanation and in any case it's not important to this video.
It’s just another way dry air sucks! Anyway, the only way we can get relative humidity to go back up after heating the outside air is to add moisture into the air ourselves. And that’s what humidifiers are for. You add water to them, and they make it evaporate into the air to increase relative humidity. And of course, there are multiple types of humidifiers. Shall we talk about them? Let’s talk about them! Including one you can make yourself. This is the ol’ standby Vicks warm-mist style thingamabob.
It’s in two parts - a weirdly shaped plastic jug which contains the water and is nearly impossible to effectively clean, and, uh... this doohickey which sits in the water. All this does is slowly boil water. Seriously.
That’s- that's all it does. And they’re really finicky, too - if your water doesn’t have enough minerals in it, it won’t work and they have to put a label on here saying, "hey if this doesn’t start working in 10 minutes, try adding some salt. See if that helps." If it’s not clear I don’t really care for these, but after all they’re not marketed as humidifiers exactly. They’re more of a personal care product meant to be used in conjunction with Vicks' latest cold-fighting rubs or whatever. But the main reason I don’t like them is simply that boiling water is a rather energy-intensive method of vaporizing it. This uses about 50 watts continuously which, yeah, that’s not a whole lot- [voiceover] Turns out it’s much worse than this! I was somewhat suspicious that it was only drawing 50 watts, so when shooting the B-roll for this video I decided to descale the thing with vinegar.
This is all the lovely crud that came out of it. Yummy! After this descaling, it’s now producing more steam and pulling 200 watts! That’s… a lot. And I’ve apparently uncovered something of a mystery. Its power consumption is just… weird.
It seems to slowly rise when you plug it in, and if you remove it from the water it instantly falls to practically zero. I’m starting to wonder if this thing is actually an electrode boiler. That would help explain the need for salt in some circumstances. I’ve been trying to find a concrete answer online but without much success. So, I’ll be taking this thing apart in a quick and dirty video on my second channel. A link will be below.
I do just want to say, though, that I’ve sold its ability to humidify a little short. It will, assuming it’s operating correctly, go through a gallon in 12 hours which is fairly substantial output. It will just use a lot of energy in the process, and I stand by my statement that these are finicky and annoying. Another common humidifier style is this one! The ultrasonic cool mist variety. This is, in my opinion, certainly the most interesting style of humidifier.
A piezoelectric disc sits at the bottom of a pool of water. A very high frequency signal, in the megahertz range, is fed to this disc which causes it to vibrate at that frequency. This causes micron-sized water droplets to form on the surface of the water, and a small fan draws in air from below the device and pushes it out through this tube. When the tank sits on the base, the airflow carries these tiny water droplets up through this hole in the tank, and a little hat with a nozzle helps direct that water and air mixture upward and outward. What comes out of here are microscopic droplets of water suspended in the air - that’s why they’re visible. In a sense, this thing generates clouds! But they quickly disappear.
The miniscule size of the droplets means that they’ll evaporate nearly instantly, and thus the relative humidity of the air in the room will go up. These humidifiers are fairly effective - this particular unit will go through its tank of water in about 24 hours. They also don’t require all that much energy. At its maximum output, this unit consumes about 32 watts, though it is adjustable.
But, these aren't perfect. There’s always a catch. If you have hard water, the mineral content of your water ends up in the air. Because the water is thrown into the air as liquid water and evaporates after it exits the device, you can experience a white dust forming on objects, particularly near the humidifier itself. This is the same limescale that you deal with in your sinks and shower, but now it’s all over the place.
That’s neat. Now, that particular problem can be solved by filling the tank with distilled water purchased at a store, but that’s annoying and also becomes a significant expense if you need to fill it daily, and/or have multiple units. There is also the fun fact that whatever mold, bacteria, chemical impurities, or other goodness might be in the water tank… will end up in the air, too.
I'm... I'm pointing right at it. Now to be clear, this isn’t a gigantic concern, and it's certainly not unique to ultrasonic humidifiers. And then, of course, the last common style you can buy in stores is this kind. "Invisible cool mist" is marketing speak for evaporative. Evaporative humidifiers simply help water evaporate by providing a large surface area for it to cling to and a flow of air for it to hitchhike upon.
They are extremely simple, yet also extremely effective. You’re right - I said this one wasn’t very effective, but here’s why: this is its wick, right? And... This is the wick of a whole-house humidifier. See the difference? Here’s the humidifier this giant wick belongs to. It’s brown and therefore excellent. This style of humidifier is sometimes referred to as a console humidifier, and it is conceptually identical to the little Walmart one, but scaled up and improved in a number of ways.
That said I’m not entirely thrilled with it, and I’ll discuss my many quibbles as we go along. It is, however, undeniably excellent at its job. The device itself is little more than a large plastic box on wheels (with simulated woodgrain excellence) and a fan. The fan sits on top of the box and when running pulls air through this vent in the rear and blows it out the top. The wick sits directly in front of that vent, and you’ll notice that the vent doesn’t go all the way to the bottom.
That’s because, of course, the wick needs to sit in a pool of water, and a vent going to the very bottom would kinda ruin that prospect. You can see that the water level isn’t much lower than the bottom of the vent, which makes moving this thing wonderfully stressful! And with that, here comes my first quibble: The box claims this has a 5.4 gallon capacity which is ridiculously misleading. See, this is its water tank. This is 2.5 gallons.
Roughly three gallons sits in the bottom of the humidifier, but that level is kept constant by this bottle feeding it. When the bottle runs out, it will continue to run for a little while and use up some of the water in the bottom, but that makes filling it a two-step process - filling the bottom of the humidifier itself, and then the bottle. You could just fill the bottle, but then you’d need to immediately do it again after it emptied at least some of its contents to fill the bottom back up to the correct level. Even worse is that a float switch prevents it from running when the water gets just an inch or so below the full level meaning you could never get it to actually output 5.4 gallons of water in one go. Therefore, in my opinion, for all intents and purposes this has a 2.5 gallon capacity.
And, aside from this particular numbers nonsense, the bottle itself isn’t the best. I routinely have to re-seat this cap or else it will leak, a mishap that would result in the bottom being overfilled and water spilling out the back! This thing certainly ain’t without its problems. How's that for a product endorsement? Anyway, here’s where things get slightly interesting. The fan isn’t just an ordinary fan.
It is a fan controlled by a humidistat. A pair of dials, one of them also being pressable as a button, serve as a basic user interfffff [with immense disappointment] it’s blue. Blue! Wha, wha, why does it have to be blue? And so bright? Manufacturers of apparently literally everything now cut. it. out.
Nobody needs this. It needs to be readable, not eye-piercing. Geez.
What if this were in my bedroom? Don’t you think I oughta be able to, like, sleep? You didn’t even put it on the box, it’s not like you thought you’d make another sale by being hip and with it with the blue ell eee deez. Bring back dull, boring red, amber, maybe green displays, please. I am so over this. Where was I? Right, so, atrocious display aside, which I will just go ahead and fix right now by applying a LightDim decal up top - I truly cannot believe this product needs to exist yes I will get beyond this tangent... you can select between four fan speeds and set the desired relative humidity in increments of five percent.
Built into the power cord is a hygrometer which it will use to measure the relative humidity, and the onboard microcontroller will cycle the fan on and off accordingly. The fan will turn on when humidity is three percent below the setpoint, and it will turn back off when it’s achieved one percent above. One thing I’ve been genuinely surprised by is how accurate basic hygrometers apparently are these days.
The humidifier’s display reads within just a couple of percentage points of both this analog dial and what my smart thermostat reports to me. Honestly a little surprising, but anyway the benefit of having a humidistat is tremendous. Being able to self-regulate means it can respond to different conditions appropriately and keep humidity levels consistent.
And it’s been very interesting to observe. I have it placed in a central location near my thermostat, and when the heat isn't running neither is the humidifier. But, within just a few minutes of the heat kicking on, the relative humidity falls to the point that it needs to run.
This makes perfect sense because the now warmer air can absorb more moisture, therefore its relative humidity has fallen slightly. The humidifier will continue to run for about five minutes after the heat has shut off. And then it will have satisfied the humidity set point and go idle. What’s really fascinating is that it has a remarkably consistent reading as the temperature gradually falls.
I have it set to 50 percent, and after stopping at 51, it may fall back to 50 or perhaps even 49 percent… but no more. It takes until the heat comes back on for humidity to fall beyond that point - and this appears to be the case throughout the house, according to my little hygrometer friend. I’m actually genuinely curious about this because it seems moisture leaves the air at a rate correlated to its temperature drop.
I run my thermostat on a program so that the temperature cools down by 4 degrees at night and even then - the humidifier won’t run until the heat comes on again, and that can be hours later. Humidity stays right near 50% the entire time the temperature is falling. It’s fascinating, though at the moment it’s not terribly cold yet so perhaps this behavior won’t last. Anyway, though this thing is ugly and annoys me in several ways, it is undeniably great at humidifying, especially from an energy standpoint.
Its fan is quite large so it uses the most energy of any humidifier we’ve seen so far while it’s running (about 65 watts at its low fan speed) but it only needs to run for about 6 hours on a typical day - and that’s on its lowest fan speed. With my current usage, it goes through the entire 2.5 gallon bottle daily. Do the math there and we find it uses 144 [but it's actually 156] watt-hours per gallon. Certainly a weird metric, but hey! It works.
The ultrasonic mister takes the same amount of time to go through 1 gallon at 32 watts continuously which means it uses 768 watt-hours per gallon. That’s more than 5 times the energy per unit of humidification! Oh, and the standby power consumption of this large unit is excellent - only about a third of a watt. Despite that garish display. My old dishwasher used triple that! Honestly, it’s amazing how much water this thing adds to the air when it runs. Just feeling the air coming out of it is impressive, it’s downright swampy.
Leaving the hygrometer on the top reveals that the air it supplies is at least 70% humidity. To give you a sense of how fast it goes through water, well you can hear the bottle go “glug glug glug” as it replenishes the water level [fan noise, with a faint "glug glug glug"] and this happens more frequently than every five minutes when it’s running! It’s amazing, this thing is just excellent at getting liquid water to evaporate with nothing but airflow. Setting this thing up has frankly been a little astonishing to me.
It’s so simple, yet extaordinarily effective. Using less energy over a day than this little ultrasonic humidifier it's able to take care of my entire home and not just a single room. I’ve been checking with my hygrometer and, indeed, humidity is pretty consistent from room to room, varying only by about five percent. Granted, this is ridiculous overkill for the size of my home and I do have the benefit of a forced-air furnace to help move air around. But, it really seems that evaporative humidifiers are, at least in many respects, the best.
Of course, there’s a catch. And it’s, uh… kinda big. Evaporative humidifiers can get… gross.
To be clear, all humidifiers get gross over time but the evaporative style tends to present the most opportunities for grossness because there’s a giant damp sponge sitting in a pool of water that has air forced through it by a fan, and thus everyone’s favorite mold spores and bacteria are brought right to a lovely place to live. It’s great. Now, there are ways to combat this problem.
First, the wicks are almost always meant to be replaced seasonally, and there are water treatment products available to inhibit bacterial growth. I’ve been using this for a while with regular water treatments and so far no musty odor has developed, which is the most common complaint of this style of humidifier. The particular treatment I’m using is supposed to help with mineral buildup, too, but we’ll see.
But, here’s where I have good news. This is conceptually a very simple device. And that means, you can make one yourself! All you need is something to absorb water and provide it with a large surface area. And you have plenty of those - towels! Take a large bowl, fill it maybe a third the way up with water, and submerge the center of a small towel. You may need to weigh it down with something. Terry cloth is great for this - that’s why towels help you dry things, after all: they have lots of little fibers for water to cling to.
Those same fibers provide places for water to evaporate from. Try experimenting with different bowls, towels, quantities of water, etc. To gauge the effectiveness of your invention, go ahead grab one of these little hygrometers. They’re not the most accurate things out there, but plenty good for giving you guidance and they only cost around $5. You can speed up evaporation with a desk fan pointed at the towels. And, best of all, you can simply run this improvised wick material through the laundry and change it however frequently you’d like.
Now, this isn’t that effective, I won’t lie, but a quick test in my roughly 100 square foot office showed it could maintain 50% humidity with the aid of a fan. And that was with a, frankly, awful towel placement. What I’d love to see come to market is a sort of rack meant to hold towels maybe a kitchen towel or shreds of towels in a zig-zag, vertical arrangement sort of replicating this wick cartridge but with a washable towel rather than this paper honeycomb stuff. It probably wouldn’t work as well as these paper wicks, but it would be a fun thing to try. Just put it in a shallow pan and sit it in front of a fan. This might even push me to buy a decent 3D printer… But, good news for those of us who just can't be bothered, the same manufacturer of this large console makes what they call a “mini” console and it is delightfully simple.
It is little more than a bucket, a fan, and two wicks. The wicks are placed in these slots, a cowl sits between them, and a fan controlled by the exact same humidistat (and with unfortunately the same blue LEDs…) forces air through the wicks when necessary. It takes in air through the sides and blows it out the top, nicely moistened. This isn’t as effective as the big brown beast over here simply because it’s smaller, but it’s much, much more user-friendly. And also quieter, at least on its low fan speeds.
Filling it is as easy as filling a bucket because... that’s what it is. Just take the fan off and carry this to a sink. Much less finicky than dealing with a tank or jug, and a lot easier to clean.
Though in this case there’s a weird quirk in that, the more you fill it, the less effective it will be because less of the wick is exposed to air. It’s probably best to keep the water level at about half the wick’s height or less. Here’s a pro-tip for you, should you decide to purchase a humidifier like these. If you use a water treatment product, which I highly recommend you do, put it in a soap pump! Figure out how many pumps it takes to fill, say, a tablespoon and use that to determine how many pumps you’ll need every time you fill your humidifier.
It’s much less messy and more consistent, too. I decided to purchase this amber-glass pump just in case the chemicals in the solution are sensitive to light (which, uh, they probably aren’t given the jug it comes in) but you can absolutely just use a well cleaned-out old soap pump. In this case I know I need to add 15 squirts every time I fill this bottle. Also, for whatever reason, large humidifiers like these seem to only be available in hardware stores, at least in my neck of the US.
Your general big-box store like Walmart seems only to carry small, single-room units, though weirdly enough when I was last at Walmart they sold not only these exact hygrometers but the same water treatment chemical I'm using in these, too. So, yeah. Don’t know why that is exactly, but I’d also recommend that you buy a few spare wicks for the years ahead. Any large hardware store should carry them, and to my fellow midwesterners, Menards has plenty. So, that’s about all I have to say here. Even though these evaporative humidifiers aren’t the flashiest or most technically intriguing, they seem to do their job extremely effectively and efficiently.
I would like to suggest a few revisions to this particular design, though. What I’d love to see is a wick that is held much higher up, allowing the tank to hold much more water, perhaps 10 or more gallons. Rather than requiring it to sit in a pool of water, I think it would be neat if a pump were used to bring water up to the wick. This is actually a fairly common design of large swamp coolers. This design would allow it to run for days without stopping. I imagine one difficulty with this, aside from the simple fact that the pump then becomes a thing that can fail, is that this would make it a lot louder.
A method of catching the water so it didn’t fall from a great height would need to be devised, otherwise you’d hear a constant trickling from the thing when it runs. Plus, of course, this would add tubing and thus more places for mold and bacterial to find refuge. So maybe it’s not the best idea, but I will say to the folks at AirCare that I really don’t like the float switch on this unit. See, instead of using it to simply alert you that it’s empty, it shuts the unit off. I would much rather it continue running the fan when it runs out of water so that the wick can actually dry out. Turning the unit off means that stagnant water will stick behind both in the wick and in the bottom, which is a little unsettling to me.
Also, the implementation of it is just super janky. It’s a stick with a styrofoam float that a ring on the wick cartridge keeps steady, and then it pokes the underside of the fan. I’ll probably just disable that switch, maybe force the stick thing up all the time by putting a rock under it or something.
The simple bucket one, for what it’s worth, has no float switch so it’ll just run to its heart’s content no matter what the water level is. I much prefer that. Now before I go, I do want to address that these sorts of portable units are by no means your only option. Whole-home humidifiers that get installed into your home’s HVAC system are also fairly common, and wouldn’t ya know it - those are evaporative, too! These units will divert some of the air flowing through your ductwork through themselves and are plumbed into a water supply. There’s often an absorbent pad or wheel which also requires periodic replacement, though sometimes non-porous materials are used which only require cleaning.
Still though, if you’ve been using one of these and haven’t ever opened it up... you might want to look into that. Since I didn’t already have one of these in my HVAC system, I just went for a standalone unit.
And, despite its many little annoyances, I’m overall very happy with it. Certainly it’s made the winter much more bearable. My lips were starting to get badly chapped around Christmastime, but now that I have this running that’s gone away.
Usually it’d be chapstick time. And genuinely, I feel warmer now with the thermostat set to the same temperature. I don’t know why this surprises me, as after all humid air always feels more oppressive in the summer, and drier air feels cooler, but it did surprise me. The air is just much more comfortable in so many ways. If you want to see how a humidifier might help you, why not try and make your own, first? It at least will give you something fun to do. Anyway, toodles! ♫ moistly smooth jazz ♫ This is what purports to be...
yeah, no it's facing the right way. Shouldn't have second guessed myself. ...plastic base supports... shoot. That was going great! ...sits in a shallow pool of water and capillary act... dew do be fluef ah heuhhh that makes it appropriate for small rooms, but not a lot much else. Not much else.
Why did I say a lot much? That's dumb. Yeah, that's not a whole lot but it's also not [stops abruptly] That cat is having fun upstairs. [rumbling as the cat runs around] But it's also not gonna be ... it's not gonna be do much! Why does it have to be blue? And so bright? Heh, no that's way over-the-top. Secret messages at the end of the videos in the captions? I have no idea what you're talking about. You must be thinking of some other channel that does that regularly.