this post was submitted on 30 Jun 2025
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submitted 1 week ago* (last edited 1 week ago) by xkcdbot@lemmy.world to c/xkcd@lemmy.world
 

xkcd #3109: Dehumidifier

Title text:

It's important for devices to have internet connectivity so the manufacturer can patch remote exploits.

Transcript:

[A store salesman, Hairy, is showing Cueball a dehumidifier, with a "SALE" label on it. Several other unidentified devices, possibly other dehumidifier models, are shown in the store as well.]

Salesman: This dehumidifier model features built-in WiFi for remote updates.
Cueball: Great! That will be really useful if they discover a new kind of water.

Source: https://xkcd.com/3109/

explainxkcd for #3109

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[–] originalucifer@moist.catsweat.com 85 points 1 week ago (12 children)

welll........ devils advocate.. i could see the wifi being used so the device can be incorporated into the home automation system [climate control]. its not about dehumidifying, its solely about engaging the dehumidifying as needed.

[–] NocturnalMorning@lemmy.world 139 points 1 week ago (15 children)

Yeah, or the manufacturer bricks the device bcz they want to sell you a new one.

[–] Badabinski@kbin.earth 32 points 1 week ago (1 children)

That's why projects like this are great: https://github.com/Hypfer/esp8266-midea-dehumidifier

My Midea Cube dehumidifier can never be bricked and will never send data outside of my home. It talks to Home Assistant via MQTT and nothing else.

[–] TachyonTele@piefed.social 9 points 1 week ago (2 children)

A dehumidifier that doesn't have any wifi can't be bricked either.

[–] kn33@lemmy.world 19 points 1 week ago (5 children)

Yeah but I want to control it with the average humidity from sensors across my house

[–] Jessica@discuss.tchncs.de 4 points 1 week ago (1 children)

It's almost like you can just set the dehumidifier to a certain humidity level and fan speed and then never touch the settings again. That's what I did with my humidifier. It's as dumb as a box of rocks, but it quits working during the summer when the humidity goes up and then turns back on the rest of the year with zero interaction besides adding more water

[–] kn33@lemmy.world 4 points 1 week ago

You can, but it only measures the humidity at the (de)humidifier. I want it to account for the state of the whole house.

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[–] Badabinski@kbin.earth 5 points 1 week ago (1 children)

I mean, yeah. I wouldn't have found that project and gone to the effort of using it if a simple dehu was all I needed. I wanted something I could control with my local home assistant install, and you can't just hard power cycle a dehumidifier, it kills them.

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[–] blackbelt352@lemmy.world 50 points 1 week ago (1 children)

Dehumidifiers already do that. They're equipped with hygrometers that kick the machine on or off depending on the relative humidity. It's old tech and it's pretty reliable, wifi isn't really necessary for it.

[–] AnyOldName3@lemmy.world 4 points 1 week ago (11 children)

The built-in hygrometer's not necessarily going to be as good as a well-designed home automation system, especially if the fan's not running all the time, so it has to wait for damp air to diffuse into the machine. It also lets you do other things, like not bother turning the dehumidifier on if there are open windows if you've got some way to detect that, or report the humidity to something that will graph it. It's not stuff that most consumers will care about, but a microcontroller with WiFi like the ESP8266 or ESP32-C3 costs less than an accurate hygrometer chip, so it doesn't make much, if any, difference to the final price, particularly if the product was going to use a microcontroller anyway.

[–] Geometrinen_Gepardi@sopuli.xyz 12 points 1 week ago (2 children)

It's ironic that you can implement all this cool automation for a device but in the end still have to manually lug water to it.

[–] Cocodapuf@lemmy.world 11 points 1 week ago

Well it's a **de-**humidifier. You need to lug water from it. For the dehumidifier in my basement, we have it hooked up to a hose that takes the water right down the drain.

But I do take your point, it is pretty funny.

[–] TachyonTele@piefed.social 3 points 1 week ago (1 children)

Like how every source of power is still steam since before the industrial revolution.

[–] cynar@lemmy.world 9 points 1 week ago (4 children)

Just most sources of power. Photovoltaic, wind and hydro aren't steam based.

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[–] yucandu@lemmy.world 3 points 1 week ago (1 children)

a microcontroller with WiFi like the ESP8266 or ESP32-C3 costs less than an accurate hygrometer chip

No it doesn't. Those micros go for $1-2 bulk, but capacitive hygrometers are 10x cheaper.

[–] AnyOldName3@lemmy.world 7 points 1 week ago

I can get a board from AliExpress with an ESP32-C3 on it with free shipping for £1.10, so I'm not inclined to believe the £0.765 unit cost for a 5000-part reel from Mouser is really the cheapest way to get them in bulk as the other parts on the same board and the shipping have to cost something.

The cheapest hygrometer that Mouser sell is £0.748 per unit for a 10,000-part reel, and its datasheet says not to leave it for more than 60 hours in greater than 80% relative humidity (which is a pretty likely scenario for a dehumidifier) as it'll drift, and if it happens often, it'll age faster. You need to spend more to get rid of that restriction. I'll concede that the accuracy penalty if you cheap out isn't as bad as I thought - I'd not actually looked at a datasheet to see how badly modern hygrometers would drift, I just knew that they did - so plenty of manufacturers wouldn't care, but the parts are still comparable prices, not a factor of ten like you're claiming.

[–] Cocodapuf@lemmy.world 3 points 1 week ago (2 children)

but a microcontroller with WiFi like the ESP8266 or ESP32-C3 costs less than an accurate hygrometer chip

Ok, two things.

First, the cost of the Wi-Fi chip is clearly not the issue here. The real expense/concern is the effort and software mechanisms needed to secure that network connection. Connecting to the Internet is easy, securing that connected device is hard.

Secondly, at some point you still need the hygrometer, there's no way around that. Either your dehumidifier is tracking humidity, or your home automation system needs to track humidity. And you can't like... get that data from the web somehow, you need a local sensor, and it will generally only make sense to have it in the same room as the dehumidifier (meaning not necessarily where other smart home components are set up).

So, first off, smart devices shouldn't need to connect to the internet, only the local network. I have everything connected to Home Assistant, and then for access outside the house I have HA connected to the internet, meaning I only have one point I need to secure.

On your second point, I think the poster above was talking about having both an in-built as well as wifi-accessible external sensor. It makes it possible to have a more powerful dehumidifier in one space, running to a lower humidity than needed based off what's going on in other rooms. Then have that air circulated by other fans, etc.

[–] AnyOldName3@lemmy.world 3 points 1 week ago (7 children)

You're missing my point. It's likely that the cheapest way to design and build a dehumidifier these days will already include a microcontroller interpreting results from a digital hygrometer because these components are cheap and easier to work with than purely electronic/electromechanical designs with no microcontroller. The cost of switching from a non-WiFi/Bluetooth/Zigbee microcontroller to one with one or more of these networks is negligible, and once you've got it, it's not meaningfully more expensive to pay a software engineer to expose the on/off switch and hygrometer readings via that network and have the marketing people write Smart! Now with WiFi! than it is to skip it and pay the marketing people to come up with some other nonsense to put on the box. If you care about security as little as the average IoT vendor does, then it's nearly free to turn a dumb device into a smart one, so if it makes a handful of extra people buy the device, manufacturers will make things smart. For a dehumidifier, there are reasons why a handful of people will prefer a smart one, so smart dehumidifiers get made.

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[–] Sibshops@lemmy.myserv.one 19 points 1 week ago (3 children)

To steel-man the argument some more, if you have variable-rate electricity, it could turn on when electricity is cheap.

[–] dfyx@lemmy.helios42.de 9 points 1 week ago* (last edited 1 week ago) (2 children)

This can be done with something like Zigbee. Or even simpler: you hook a non-connected device up to a "smart" power socket. No need for the device itself to talk to the outside world.

[–] Zachariah@lemmy.world 5 points 1 week ago (3 children)

The solution to too many unnecessarily-connected devices is more connected devices?

[–] dfyx@lemmy.helios42.de 5 points 1 week ago* (last edited 1 week ago)

The solution is not more but different connected devices so I can decide for myself what needs to be connected and by which protocol. Get the dumbest device on the market, no wifi, no internal clock, maybe not even a humidity sensor and then, if and only if I need to remote control it, for example to put it on a schedule, I can use the cheapest "smart" device on the market to connect it to an in-house machine that can turn it on and off.

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[–] Hawke@lemmy.world 3 points 1 week ago* (last edited 1 week ago) (2 children)

You still have to have some device connected to the internet. This just transfers the problem from the humidifier to the outlet.

[–] ThePantser@sh.itjust.works 9 points 1 week ago (1 children)

Zigbee is local and if you really wanted to you can use Home Assistant 100% offline it will be just neutered and basic.

[–] originalucifer@moist.catsweat.com 7 points 1 week ago (3 children)

im not sure why all these people jumped from 'wifi' to 'internet' as if they were the same thing. no one should be exposing their automation devices directly to the interwebs

[–] dfyx@lemmy.helios42.de 4 points 1 week ago (1 children)

Sadly, many wifi-enabled devices only work with some proprietary cloud-service and even if not, they're only one configuration error (or intentional backdoor) away from talking to the outside. Better have something that isn't physically able to talk to the internet no matter how badly I fuck up its configuration and my firewall.

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[–] dfyx@lemmy.helios42.de 7 points 1 week ago (1 children)

I run home automation with lights, switches, outlets, heaters and some more and not a single device has internet access. They all use Zigbee (a simple radio protocol) to talk to homeassistant which is open source and hosted on a machine that lives under my desk.

Separating tasks between the dehumidifier and outlet has the advantage that each individual device can be a lot simpler, leaving less attack surface. My power outlet can't read the humidity sensor, it doesn't need to talk to an external server, it doesn't even need to know that the thing connected to it is a dehumidifier. It's just a chip that receives a radio signal and toggles a relay on or off. That's it.

Separating the two concerns also lets me replace the devices separately if one breaks or my requirements change. If I suddenly need wifi or bluetooth instead of Zigbee or if it's for some reason no longer supported by homeassistant, I can just replace a 9€ outlet instead of the whole dehumidifier that could get bricked by the proprietary app losing support.

[–] ThePantser@sh.itjust.works 5 points 1 week ago

Home automation is still a dark art as far as the common person is concerned. Full of fear mongering from the media.

Much like 3D printing was very mystical and full of "oh no 3d printed guns!" We have gone full appliance with 3d printing and it's no longer gatekeeped by geeks in their basements.

I'm glad I still have at least one hobby that hasn't gone mainstream and I can still geek out on ESPHome.

[–] Stillwater@sh.itjust.works 6 points 1 week ago (2 children)

You could do all that without internet connectivity, just sayin.

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[–] DarrinBrunner@lemmy.world 3 points 1 week ago (1 children)

Because times when electricity is cheap coincide with the need for lowering humidity?

[–] cynar@lemmy.world 4 points 1 week ago

Some places do electricity costs in 30 minute periods. If you know cost will spike when everyone gets home, and the sun sets, then running early makes sense. Other times, holding off for an hour might be more useful.

[–] programmer_belch@lemmy.dbzer0.com 4 points 1 week ago (1 children)

That's right, this would mean that the device has an api to activate or deactivate it through WiFi by sending it commands and I can make it unable to connect to the outside internet right?

Or I can only activate it with the proprietary app that doesn't even have a working schedule?

Connecting to WiFi is good when I have full control but not when the manufacturer does

[–] bob_lemon@feddit.org 3 points 1 week ago

Yeah, devices that can run fully local are the best. They can be integrated into Home Assistant (or similar), with full control over them. No reliance on a remote server or proprietary app.

[–] DarrinBrunner@lemmy.world 4 points 1 week ago* (last edited 1 week ago)

That's the feature they sell. But, its real purpose is to monetize your data and/or lock you into some sort of ridiculous subscription service and/or run ads.

That's pretty much ubiquitous for "smart" devices.

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