Hi, you've made it to the Connextras video where I explain what the heck is going on with
these wires and all the stuff that I did with this uh dehumidifier here. If you got here without
seeing the main channel video, there's a clicky thing. This is to explain an experiment that
I ran on this thing uh and why it didn't work. Well, I actually don't know why it didn't work,
but my idea did not pan out. So to give you a quick recap of what that video is about,
that way you don't have to watch the whole thing if you don't want to. This is a rotary desicant
dehumidifier. And the cliffnotes version of how it works is this rotate - this wheel of silica
gel rotates very slowly. Air is drawn through the whole wheel except for this beige section here. The
beige section has a heating element which is getting the wheel very hot so it releases the moisture.
Uh, and then that hot damp air goes through this heat exchanger where it condenses into liquid and
goes into a bucket. It's a clever idea, but it's not very energy efficient. And I had this question
in my head, which was "is this actually an optimal amount of time for the silica gel to be uh
charging versus regenerating?" The wheel rotates at about one half of an RPM. It takes almost exactly 2
minutes for it to rotate, which means it's exposed to the room air for about 80 seconds and then it's
recharged for about 40 seconds. And I was just not entirely convinced that that was optimal. I had
no idea how much, you know, moisture the silica gel could reasonably be expected to adsorb in 80
seconds, but I just wasn't convinced that that was enough time. So, I got my uh you remember
you may remember these temperature controllers from the space heater... well not the space heater
video the HVAC system sizing video and these happen to have a duty cycle control mode. So,
I set one of these up to run for 4 minutes on and then four minutes off. And I disconnected
the wires from the heating element and the blower motor that actually pushes air through here. And
I'll explain my reasoning there. And I wired them to a plug and plugged it into this. So, first I
just did a preliminary test where I had it exactly as you see it now, completely out of its case, but
powered on and operating. It didn't seem to care that I had disconnected the heater and the blower
motor. It was working fine. Uh, and so this 12volt fan was running, pulling air this way, but it was
completely out of its case. And uh that meant the airflow situation was not normal and there would
be very little air flow to cool off the straw radiator thing. So I literally just put a paint
can here with a tiny little desk fan blowing at this and um let it run for two hours as normal. In
that time, it extracted 60 grams of water, which was nowhere near what it can normally do. But that
made sense because again, it's completely sitting out like this. That's... so of course it's going to
be a different number. So then I unplugged the uh heating element thing from the wall and plugged
it into my duty cycle controller, which turned it on for 4 minutes and then turned it off for
4 minutes. And my thinking was that's going to make sure the desiccant wheel actually gets four
minutes of exposure to the air before it starts regenerating and then it will have four minutes
of operation as this thing typically operates. And I killed the blower motor on purpose thinking that
um I would want to completely shut - like I would want to stop the flow of hot air as quickly as
possible and if this was continuing to go on then the moisture that was in these tubes would
potentially just get reabsorbed onto the desicant as it was moving through. So it felt like it made
sense to turn off both the heating element and the little blower here. And surprise surprise,
despite the fact that I had cut the power draw in half by turning the heating element, by running
it at a 50% duty cycle, it extracted 70 grams of water. So, it got more water out of the air
with half power. And my mind at first was like, "Eureka! This thing is put together poorly. Why
didn't they design it differently?" But because my brain understands the fundamentals of science, I
changed way more than just one variable. So before I concluded that that actually meant anything,
I needed to somehow get this back in its case and do the experiment again. And that I actually
filmed. The first one I I just took pictures of the water readings, I think. Um and I actually
filmed the setup of the second test. And then, well, it didn't work. First, the thing broke.
It just wasn't It was suddenly beeping non-stop. And what that very well might have been, uh, it
has two temperature sensors in the heater circuit thing um, to determine if it's overheating. And
I thought they might be thermal switches, which opened. They don't seem to be based on my testing
with a voltmeter. So, I don't know if that's why it died, but certainly what I was doing by killing
the power to the heating element and the blower at the same time, things were getting hotter than
they should be. When operating as normal, whenever you turn this off, it keeps the fans running for
like 30 seconds and then turns off. So, I knew I was kind of asking for trouble. But regardless,
nothing actually broke. It's just the control circuitry was was deciding I'm not going to work
for you anymore. So I then had to wire the fan to these wires here. That way I could run this
in completely manual operation. So I needed to this wire is going was going to a second
plug. This was going to a DC power supply to run the fan. And then the plug oops the plug
that I had already wired to here the heating element and the blower went into this thing.
Well, and the wall originally. So, I repeated the tests with it fully powered on as normal,
just the control circuitry was not awake for any of this. And I think uh hold on, I wrote this down
somewhere. So, once it was reassembled with the wires poking out carefully and having everything
running as it should, it extracted 159 g of water in 2 hours, which is pretty typical. And then I
plugged the heating element and blower into this and it extracted 74 grams of water. So it's Yeah,
I was pretty bummed when that happened because I really thought that I had stumbled upon like
there's something because this thing just runs the heating element at full power uh in the high
span highspeed mode. High fan speed mode. That's what I meant. It runs in full the heating element
is just on if you have this in its maximum power mode and that just didn't seem right. It or it
seemed like that might not be right, but it's right. So, the experiment was a failure. Um
80 seconds appears to be just as much time as required for this to uh adsorb as much moisture
as it can hold on to. And you know, in hindsight, that makes that kind of makes sense. I mean, it's
it's not like this can actually hold on to much moisture at all. Um, but you're not you never see
it wet. That's not how this works. It's just um I mean on the molecular level, I couldn't tell I
couldn't tell you what's happening, but molecules of water are sticking to the silica gel and then
they're being able to pushed out from the other thing. Um, but the 80 seconds in the airirstream
and then 40 seconds in the hot airirstream appears to be pretty close to ideal. So,
I have no idea what happened when I tested it the first time, why it was able to get more moisture,
but um I'm guessing that was just a fluke because it it it was only a small...
Well, the other thing it could be is um when this is running at half power, it does cut the power to the heating element in
half. I shouldn't I shouldn't say half power. In the night mode, I think is what it calls it,
the heating the power draw drops to about 150 watts. So, when it slows down the air flow,
it also slows down the heating or it lowers the heating power. So, I guess effectively because
the air flow was messed up in my situation, I was doing the same thing with the heating element,
cutting it down to half power, but I was doing it uh through a duty cycle through timing rather than
actually lowering the power power level if that makes sense. Um yeah, so this is just kind of a
bit of a rambly quick like what quick explanation of what I was doing. I I I had started to write
I had a section in the script where I explained this experiment, but then I realized this doesn't
it doesn't do anything. It was just me making it was just an excuse to make fun of the people who
put this together, but they did nothing wrong. So, yep. That's all there is to this video.
Bye!