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Rotary desiccant dehumidifiers. Neat, but flawed.
🕑 Added 2025-08-30 01:50:59 +0000 UTCHello! The next main channel video is ready. You can watch it here on Patreon or on YouTube through the link below:
Much of this was meant to be included in the first video on dehumidifiers, but that one ballooned out of control and I felt this was interesting enough to make its own. But I'll admit I wasn't as meticulous with this as I typically am - partly the testing because tedious, but also there's not much useful guidance I can give about these. It's an interesting, but weird and generally bad-for-the-US approach.
Oh, and I apologize but captions will have to wait until tomorrow. But the much improved auto captions are already in place.
In other news, I haven't updated you on the car videos in a bit. Everything except for a few replacement parts is now here and ready to go, but the scope of the first video (and how I wanted to introduce the series) has expanded/changed. It will likely be the first video of October, and I may not have a main channel video in September due to its complexity.
I'm going to update everyone with more specifics during tomorrow's livestream, and if you don't catch it live you can watch it later.
Thanks as always for your support!
Comments
Lee Brian Warren
Contains dry humor!
Martin Ibert
Did you really take a detour through US customary units to avoid just saying that 1 kg of water is 1 l of water, give or take?
Circuitmike
I have a fairly tightly-insulated house and as a result the CO2 levels get very high (over 2000 ppm) without ventilation. I've been cheating and using my range hood fan, which can pull that number down to the 800 range, which is good, but it's obnoxiously loud, and pulls in particulates when the air quality is bad (wildfire smoke in the summer, wood heat smoke in the winter). So I'm considering an ERV and I was hoping I could find one with a HEPA filter. It's good to know that they exist!
Chris Brosz
Have you looked into the dishwashers that now use desiccant packets for drying the dishes? Like the Bosch ones with their crystal dry feature? This last dehumidifier video looked very similar to their setup.
Dylan Neu
It's maybe not super relevant to the discussion in the video but there is a distinction between changing the relative humidity by heating the air and changing the absolute humidity by removing water. Both effectively reduce mold growth in a cold damp basement though by discouraging condensation and increasing evaporation rates from surfaces.
DrKOS
You mentioned ERV and HRVs. It would be great if you did a video on those. I have an HRV with a HEPA filter for smoke season and I love it, but no one else knows what they are or why they're awesome.
David Weintraub
I think it was to let us know the whole converting grams to ounces to fluid ounces to gallons to liters was him giving us a sly wink. Water’s density in metric is defined as one gram per milliliter or 1 kilogram per liter. He had 195 grams of water. That’s .195 liters or about .2 liters. There’s no need to do all that metric to English to metric conversion.
Amy Tobol
Haha what was going on with the slow tilt at 11:11?
Matt Deres
When the TFT model is being displayed (about 19:35), you verbally say that the efficiency is 0.71 L/kWh, but the screen graphic (incorrectly) reads 0.77 L/kWh. I assume it's just a typo, but FYI!
Aleksei Besogonov
Similar dessicant units are _great_ for moisture recovery in winter, one side goes through the incoming dry air, and the other through the exhaust moist air.
Andre Pirnat VE3BIC
Not hot enough
Markintosh
I’ve never heard of those things-it’s actually kind of cool! I can see what you mean-re: power consumption vs. moisture removed-yeah not so good here in the US. BUT… would that type of unit be good in a closed case for drying 3D print filament?? The heat would be welcomed.
Filipe Gomes
Maybe I missed some detail but wasn't your efficiency comparison unfair because you kept comparing against the performance of the regular dehumidifier in its most beneficial scenario (aka hot bathroom with humidifiers)?
Tim Boobyer
Goldair make one. I ran one for years, but replaced with a normal air conditioner based one after it broke - it's so much more effective. Very loud though, the dessicant one was whisper quiet.
Max Goldstein
Me, living in Atlanta with a bathroom where towels never seem to dry: gosh darn it.
Dukefazon
I saw many many years ago that they erected some billboards or something similar in Africa that has some weird guts that causes the humidity in the air condensate and drip down on the inside to a valve so people on those areas where they barely get regular drinking water could harvest it from the air. I don't know where this was set up and how exactly it works, I saw this 15+ years ago I feel like, or maybe even more. I think of that setup from time to time and now this device makes me think of it again. Maybe you could look into it.
Erwin Bierhof
I have two of these things, one for my unheated bedroom and one for dehumidifying my attic in winter. As my house doesn't have central heating, it's either a desiccant dehumidifier or an electric heater. When compared, the dehumidifier comes out on top cost wise. Here in The Netherlands, the winters have become increasingly wet and my 1930's home really can get rather damp. The unheated bedroom is entirely by choice, btw. The smell eventually goes away. It's mentioned in the manual of mine.
MrHammond
Thanks again for all the explanation! Here in Switzerland it's hot and humid in the summer, and cold and dry in winter, so in winter, humidification is usually more needed that dehumidification, so a unit that gets both the moisture and heat outside (I think that's called an airconditioner) is more appropriate (and unfortunately almost never installed in living spaces, in some cases even forbidden by law...)
Fox (vpternlog)
I love the Japanese hybrid heat pump + desiccant dehumidifiers.
J Ruonti
I like to assume you did all that conversion to multiple sesveral numeral units of measurements for giggles. Instead of just going from grams to litres.
Liliana
As someone who lives in New Zealand I am suddenly baffled by the distinct lack of these humidifiers in my life
Nick Loh
The "wheel" design reminds me of an odd type of humidifier I remember seeing in magazine ads a long time ago. It had a set of rotating discs half-submerged in a pool of water. The rotating discs gave more surface area for the water to evaporate and caused any dust, etc. to stick to the exposed part of the wet discs, which would then be removed as the discs rotated through the water. (I think there might have been a fan blowing across the discs to help this as well?) The stated main advantage of this was that there were no wicks that could turn moldy (the discs were non-porous) - also, it was quieter and you got some free air purification too. Don't know if they're still around though.
eaglebeagle
ooh. actually been extremely curious to see this one, and the car stuff too!
Technology Connections
there's lots to fix, this is the auto-transcript
Technology Connections
yes, that section is meant to be a nonsense joke
Will Latinette
Re your calcs: Since 1 ml of water = 1 gram (which you weighed) no need to go to US and back to metric, right? (That hurt my head... )
Jeffrey
Could one, theoretically, use the heat output of a refrigeration cycle dehumidifier to recharge the silica gel of a desiccant dehumidifier? Creating two stage monstrosity?
Technology Connections
I don't think it will be possible for a heat pump to produce air hot enough to regenerate the desiccant. The refrigerant pressures required would be extremely high.
SkaveRat
My eyelid twitched during that conversion. Congrats
epsalon
I wonder if any rotary desiccant dehumidifiers use a heat pump as the heating element rather than a resistive heating element.
NatTheCat
Small typo at 7:43 on the captions, "yink". Also "energyefficient" near 9:22. "Mist" near 9:42. A few things near 10:40 including "tear" and inconsistent representation of grams. "6.87 87 oz" near 10:53. "Flu" ounces near 10:56
Deviant Ollam
Going to enjoy this as I go to sleep super early tonight. Good luck on the live stream this weekend. Hey, I'll actually be watching it from Chicago since I'm visiting town!
Cooper Schwartz
Who woulda thunk. Heat pumps save the day once again.
Technology Connections
Yup! There's a small section in the video on commercial applications but I limited the scope here to plug-in domestic versions
Robert Sanges
These are used on a large scale to dehumidify hockey arenas. I've commissioned the large gas burner system on a few of them. The whole thing is about the size of a tractor-trailer, and there can be 3 or 4 of them in the building.
