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Comment by MrMid | Hacker News Reader

We made such chest fridge from an old freezer, and have been using it for almost a year now. The floor space it takes isn't that concerning, as it doubles as a counter top. It really is very efficient.

The only problem we have is humidity. With everyday use, a lot of condensed water gets stuck inside, the humidity goes near 100 % and the moulds really like that.

We tried many things, including making a drain hole inside, but nothing helped. We "solved" it with putting 1 kg of adsorbent (silica gel) on the bottom. It lasts about two months between regenerations, so it is quite usable this way.

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These are popular to keep kegerators dry:

https://evadry.wpengine.com/product/e-500-renewable-high-cap...

It's basically just a silica gel pack, but you can plug it in when it's saturated to recharge it, and it has a wet/dry indicator.

With a regular fridge/freezer the steady-state relative humidity should be quite low because the cooling coils will condense out a lot of the water vapour, and drain it out a hole in the back to evaporate outside the enclosure. The cooling coil is always going to be the coldest surface within the enclosure, therefore that's where the water vapour would tend to condense.

Don't chest fridges have a similar mechanism? Perhaps the problem is things being too closely-packed, so the air can't circulate - so that when the lid is opened and water vapour let in from outside, it condenses on the food etc - but this isn't then removed by the mechanism above.

The cooling in this freezer is all around the walls, and the condensed water stays on the walls and then falls down on the bottom. There was originally no drain hole, and even adding the drain hole didn't solve the problem.

It was designed as a freezer, not a fridge, after all.

> We tried many things, including making a drain hole inside, but nothing helped. We "solved" it with putting 1 kg of adsorbent (silica gel) on the bottom. It lasts about two months between regenerations, so it is quite usable this way.

Now THIS is a great idea! I have the same thing (converted old freezer to chest fridge with custom IoT temperature-controlled plug switch magic; though I now replaced it with a chest freezer that was actually designed with a thermostat allowing temperatures over 0 degrees celsius) and the same exact problem with the moisture accumulating at the bottom. The device actually has a hole to let the water out, but that's not helping as there must be a huge puddle of water before it even starts reaching the drain in one of the edges of the machine.

I might try that adsorbent trick, though I would imagine that I'd have to add some kind of grating on top of the adsorbent? Because I'd rather not want to place my water bottles into the adsorbent and have it stick to the bottom of the bottles.

Place a wick in the center of the puddle and run out out the drain hole and down a couple inches lower than the lowest part of the puddle.

The wick will act like a self-priming siphon, and carry (wick) the water out the hole and drip from the lowest point of the wick.

I am totally amazed by how well this works!!!

I've had the wick routed along the outer side of the fridge for a few days now and it managed to remove every last bit of water (when I placed it there were puddles of water all around the fridge) and successfully keeps the fridge dry now. The water evaporates from a piece of cloth attached to the ends of the wick as planned, so the entire system is maintenance-free now. During the first days the cloth piece was totally soaked, but now that the initial puddles were removed it is relatively dry and I could just place it under the bottom of the machine, so it is practically invisible.

Thanks again for that awesome idea!

Nice idea, thanks! I've just ordered a few meters of wick and will try exactly this. The puddle actually isn't a puddle; it's more that the condensed water drips down the four sides of the interior walls and collects at the bottom where the walls hit the floor. I should thus be able to run the wick around the bottom of the freezer in the edge to collect most of the water.

The drain hole is in the bottom, so I can run the wick through it and out of the machine. I hope to simply be able to attach a shred of cloth or something to the end of the wick in order to evaporate the water away to the outside air. That would make a nice, maintenance-free solution.

How do YOU regenerate the silica gel? Just let it try out? Set in sun? Bake? I'm just genuinely curious. Thanks!

I use colored indicator silica beads for desiccant purposes and when the indicator shows they're "wet"/green, I spread them evenly on a baking sheet with foil and bake them at the recommended temp, stirring occasionally, until they turn back orange.

You can buy a purpose-built device like one of these:

https://www.amazon.com/Improved-Eva-dry-333-Renewable-Dehumi...

https://evadry.wpengine.com/product/e-500-renewable-high-cap...

We bake it on low temperature for like two hours. We did it just once, so we cannot assess whether it's still efficient with the baking energy included.

But the winter is coming now, so the extra heat generated when regenerating won't go to waste.

Yep. Just bake them in the oven on low to dehydrate them.

I wonder how effective a 1kg $1 box of salt would work. I guess it would have to be dumped into a Teflon mailing bag to breathe better than the box it comes in.

Then toss it every few months. Mold won’t grow on the salt itself, so could cook with it.

Or use it as driveway deicer.

Or just but the 10kg bags of rock salt in winter for driveway deicer for like $5.

We tried 1 kg of baking soda. It absorbed a little bit of the humidity, but the mold appeared on the food itself.

we has one of these as well. they were great for overflow during big holiday events.

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