I’m reconfiguring my printing closet (~6’x6’) for a new printer and thought about enclosing the printer in a moderate sized cabinet (~2’x3’x6’ - one “shelf” of the closet) for thermal control. Since there will be inevitable opening and closing, as well as just normal infiltration of the ambient air (usu ~65F between 40-75% RH) it would seem like a good application for a Peltier dehumidifier to keep the RH in the chamber low and reduce my need to re-dry filament which has been on the machine during (inevitable) multi-day or -week downtime between projects.

  • empireOfLove2@lemmy.dbzer0.comEnglish
    9·
    9 months ago

    Peltier units are solid state heat pumps with awful efficiency. Where power consumption is not an issue, It is significantly cheaper to simply get a normal resistive heating dehumidifier, as the additional heating efficiency of a Peltier operating at 0.6 COP is not worth the upfront investment.

    Small heating box dehumidifiers are a bit of a misnomer too. All they do is heat the air so it’s relative humidity is lower since hot air can hold more water. The amount of water does not change. However for most environments this works OK. Only units with full refrigerant pumps inside that can cool the air to its dew point, condense the water out, then warm it back up are true dehumidifiers.

    • HewlettHackard@lemmy.caEnglish
      2·
      9 months ago

      I don’t think the efficiency is a big deal; you’d only have to run the peltier intermittently (e.g. each time you open the box) as long as you can drain the condensation somehow and it’s otherwise well-sealed. I’ve idly pondered OPs idea myself and I think it’s not a terrible way to dry a box. You avoid the consumables or need to recharge your dessicant materials.

      • empireOfLove2@lemmy.dbzer0.comEnglish
        2·
        8 months ago

        Yeah, intermittent operation based on RH% would probably be okay as far as power consumption goes. But at the same time, do you really gain anything in terms of performance and cost vs just resistance-heating the box up warm enough that the RH% drops below 30, and then cycling air in and out once in a while?

        • HewlettHackard@lemmy.caEnglish
          1·
          8 months ago

          You’re right, 50%@70f (let’s say Texas indoor conditions) is 19%@100f, so you’re right that just heating is probably perfectly good.

          You’d need a very sensitive filament to bother doing more. That said, if you did have a peltier with the cold side at 32f, you’d get 25%@70f or 9%@100f…which actually isn’t amazing since you still need to warm it up to 100f to get that 9%! Peltiers are inexpensive and I might still experiment with it one day, but…it doesn’t seem like a huge win.

    • dual_sport_dork 🐧🗡️@lemmy.worldEnglish
      1·
      9 months ago

      I think it should be theoretically possible to make a Peltier based machine that will extract moisture the same as a refrigerant pump machine. Ask any overclocker who’s tried to use a Peltier directly on a CPU or motherboard; it’s perfectly possible to get the cold side of a Peltier below the dew (or frost!) point when it has little or no thermal load on it.

      Now as to whether or not any commercial product exists that actually works that way is another story. I see a ton of them e.g. on Amazon, but I have not tried any out or taken one apart or anything. But with a suitably shaped heat sink you could get condensation to form on the cold side and then drip or shake or blow it off or whatever into a catch bucket, just like your basement dehumidifier does.

      • empireOfLove2@lemmy.dbzer0.comEnglish
        1·
        8 months ago

        oh, anything is technically possible. It’s totally possible to get a peltier to drive a sufficient temperature delta to condense water at a low dew point. The issue is the exponentially worsening efficiency curve as delta-T increases that would make it’s power requirements - and waste heat generation - quickly become untenable for what you’re accomplishing.

  • thantik@lemmy.worldEnglish
    3·
    9 months ago

    I put my filament on the heated bed, and put the box it came in over the top of it with the desiccant pack it came with. I set it for 38C and leave it. I feel a little more comfortable doing this with my printer as I built it with redundant thermistors on a silicone mat from alirubber, but you can do it on any machine.

  • callcc@lemmy.worldEnglish
    2·
    9 months ago

    Interesting technology those peltier dehumidifiers. I had never heard of them.

    My question would be about efficiency. I could imagine this working well in a very humid environment to save your filament.

    From my limited understanding of the physics of wet air I would imagine that it’s tough to remove humidity via condensation when the air is already pretty dry.

    Why not just remove the spool after your last job of the day and store it in a plastic zip-lock bag? That saves power, production of a peletier dehumidifier and cost of buying one. I do this and never had trouble with wet filament.

    • constantokra@lemmy.oneEnglish
      2·
      9 months ago

      In Florida, I run a dehumidifier in my garage, and it pulls a couple gallons a day. It’ll get uncomfortably dry, if you let it. It’ll keep the relative humidity down around 25%, according to its display.

      I’ve used those pellets before too. They get used up almost immediately, even in a vacuum sealed bag.

      I have a smaller dehumidifier in my bedroom. I think it cost me around 30 bucks and it also keeps things super dry. Once I have a relatively sealed space for my filament I’ll probably put one in there too.