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Question: Humidity controlled cabinet (lemmy.world)
submitted 5 months ago by to c/3dprinting@lemmy.world
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Hi all,

I'm doing an experiment with a cabinet for filament with a small dehumidifier in it. I can get it to sit at 35%, but not much lower. I've sealed the cabinet with foam tape, and dried most of the filament first.

Are there any tricks to help improve performance of the mini dehumidifier? Maybe adding more heat to the cabinet?

The goal would be to use Home Assistant and the humidity sensor to turn things on and off as needed.

Thanks!

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[–] 4 points 5 months ago* (1 child)

Are you sure it's 35% ? I've found those cheap digital hygrometers to be off by 10-15%.

I bought a box and some say 10 and some say 20. I ended up buying several different brands and price ranges of hygrometers to try and figure out which ones were correct.

I use cereal boxes with desiccant and without any active dehumidifier they stay at ~25% despite being frequently opened and closed. So like others suggested, put a large flow-through bin of desiccant in and forget about it.

Also is that a compressor dehumidifier? I suspect it's a desiccant wheel because it's so tiny.

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  • [–] [S] 2 points 5 months ago* (2 children)

    It's a compressor, which is probably the problem. I'm using a DH11 on ESPHome, so am pretty confident of the accuracy, it's down in the bottom center of the cabinet. (I designed these https://nowsci.com/only-sensor)

    Edit: Also, what do you mean by flow-through?

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  • [–] 1 point 5 months ago (1 child)

    The DHT11 has been replaced twice with similarly-priced but more accurate models, first the DHT22 and then the AHT20. In my experience, the AHT20 is a lot better than the DHT22, mainly because its power consumption is far lower, so it doesn't mess up its readings by getting hot.

    Also, at that size, I'd be very surprised if the dehumidifier has a compressor. It's much more likely that it's got a Peltier plate, and they're not very good. They use a lot of power to develop and maintain a fairly small temperature difference, so if they're in a confined space, they heat up the air quite a bit, and then the water from their tank will more easily evaporate.

    If you're willing to spend some money, a solid state ion membrane dehumidifier might be better for a small cabinet than a compressor-based one, as it'll be easy to ensure the water goes out of the cabinet instead of into a container that can't be emptied without opening the cabinet and letting more humidity in. They're definitely not cheap, though. I think they're still under patent as there's only one manufacturer that I can find, so maybe they're the dehumidifier of the future even if they're not suitable right now.

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  • [–] [S] 1 point 5 months ago

    While I'd rather have 2% accuracy than 5% on paper, it's been fine, and checking with higher quality sensor has always put me within 1%.

    Also, I mentioned in another comment it was a peltier, and I'd love to do SS but just soooo expensive. :(

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