This is the RH in my house:
It will sometimes go over 30 in the summer, after it rains. 
This just be why nothing I own ever rusts.
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What?!? I had to get a dehumidifier in here last spring. Sitting here I am at 46%RH, we hit 70 at one point, that machine was pulling tons of water out of the air. 13%, is crazy, do you all carry chapstick in your pocket?
I go through about a spool a day on each machine so I don’t bother but the few rolls I do store are in a dry box with heaps of dry packs from all the daily spools. So far they are still good years later.
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We use a lot of chapstick and hand lotion. My knuckles will crack often through the winter. But your body mostly gets used to it.
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Wow that brings back memories, my dad used to use
cow udder lotion when we lived there. His carpenter hands got all jacked up.
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Do you use heating and a fan in those , or just dessicant? I’m struggling to keep sealed boxes below 30% at the moment.
Just those little orange balls, my boxes are between 25 and 27%. 
I live in a very moderate climate though.
I have a big ziplock tub with a couple rechargeable desiccant boxes in it. Modified a chepo food dehydrator to dry the spools before they go in the box.
It usually takes me a little while to go through a roll of filament.
I recently picked up one of the commercial drying boxes. It’s working well so far. I’m thinking I should mount a hygrometer inside the 3d printer to see what the humidity is inside the chamber while it’s printing. I think it’d be interesting.
I live in a fairly humid environment as well. We hit 90% Sunday morning. I grew up in Houston. Down there your sweat has sweat. You wake up each morning with condensation on all the windows on the house from the AC running during the night.
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I finally got tired of the hassle of the old food dehydrator - It works well, but it’s a day to dry the silica gel and then a day to get two spools of filament down to say 20% in the dry boxes and then by the end of the week we’re back to 30% (which seems to be where it stays once it settles).
So the dry boxes stay, but I’ve done enough research of filament dryers to earn a PhD I think.
My thesis is:
Most people won’t want or need the extreme that I’m working to. Most people aren’t as fussy about the end finish as I tend to be, and they live in a much more printing conductive climate.
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I could easily build one that works (a filament dryer not a dry cupboard) but the cost of doing so is more than a medium priced commercial dryer (say a Sovol two spool job)
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Ironically the lower priced and medium priced ones mostly don’t actually work as well as the food dehydrator, because they don’t exhaust wet air (they do improve RH but not to the extent I want if I’m spending that sort of money, and they can be modified to be quite efficient. None the less, most peak out temps at somewhere below 60°c which is not quite enough for drying the filaments that most need it>. Remember once again I live in a very humid environment and anecdotally they work well enough in less than extreme conditions.
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I’ve bitten the bullet on a Eibos Cyclopes - which is stupidly expensive for what it is (just like Prusa’s stuff!
) but unlike Prusa’s stuff still needs modifying because it’s too hot! It has a 150W heater and can heat the thing to stupid hotativity, but does have a propensity to melt filament and spools when it does if they aren’t moving. There are a couple of nice mods including one that puts a little motor on board to make a sort of rotissery, so watch this space.
When it’s sorted, I’ll be able to dry two spools and their associated silica gel while printing. So finally I should have string free PETG, and Flex and ASA that actually work for more than about an hour!
Watch this space!
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Somehow I think it might be less expensive to just move to Europe. 
Think of all the shipping costs you don’t have to pay to Prusa as well.
I haven’t fully tested my filament dryer yet. Today’s humidity is only 57%, but I thought I’d run the dryer on some TPU. I also tossed some dessicant in the bottom of the dryer. I figure I’ll let the dryer dry the dessicant out and then see how well it holds the humidity inside the dryer.
Here’s where the temp/humidity was a few minutes after I turned it on. (24c/57% when I first turned it on)
And here’s an hour into the 6 hour dry time I have it set for
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Well this is interesting!
Yesterday was a very low humidity day for us (57%) and a very chilly 19° C (brrrrr).
I keep all filament in dry boxes when not in use, and mostly unload it at the end of the day. From previous “scientific” experiments, I’ve removed between zero and 1 gram of moisture from older PLA when drying.
I have formed a view some time ago that the benefits of “drying” PLA is mostly “conditioning” it but there’s no chemistry behind that. I am not dismissing drying out of hand, and am hoping to actually be able to print ASA in our climate with my fancy new dryer. HOWEVER -
My dry boxes tend to keep a constant relative humidity between 20 and 30% depending on ambient temperature and the state of the silica gel.
In the following photograph the box on the right was opened to the air for one hour, with 120 grams of silica gel slightly discoloured (some humidity in it) The blue filament has been in use for two years, the yellow probably about 18 months. No drying.
The box on the left has newish filament, 180 grams of freshly dried silica gel and the filament had been dried to 16% RH(4 hrs @45°) before sealing.
The photo was taken twelve hours after sealing the boxes and even allowing for a small discrepancy between the two hygrometers I would describe my drying efforts as disappointing!
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Because I can’t leave well enough alone - the dryer is great (maybe) but it doesn’t have a handle on the lid.
Fixed that today!
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Ahh, and instead of getting on with CNC stuff, I figured out a way to have the spool that’s in use turn the one that isn’t, and wheels and gears can be fun.
Apparently melting filament is a thing in the Eibos Cyclopes.
I think Adam Savage reads this forum!
In the first post on this thread I posed the idea of incorporating a small dehumidifier in a filament drying cupboard. I’ve not seen it done before or since, so I dropped the idea and spent a small fortune on ikea dryboxes and silica gel - which work to an extent, but one of my PLA boxes is presently at 45%!
This week though - IT’S BEEN DONE! Now if only I could get some information on just how well it works… fast forward to find the bits you want. (unless you want to build a cupboard)
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My windows don’t open automatically, but I have home assistant scripts that notify me my wife to open and close them. It has extended the spring and fall months where we don’t use a heater or air conditioning.
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