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Fermentation chamber- ducting air from a minifridge?

My ongoing search for an appropriately large and still cheap chest freezer or fridge has been fruitless, so I’m kicking around an idea… let me know any concerns.

Start with a cheap dorm fridge (little ones are very cheap)
Build an insulated enclosure, large enough for one fermentor (I think I’ll only need one at a time).
Run two ducts from the fridge to the box. Maybe through the front door…
Install a fan in or near one of the ducts
Run fridge full time, maybe with jugs of water for thermal mass, and hook up fan to temp controller.

In theory, I should be able to chill, but I don’t know if I can keep up with 5 fermenting gallons of beer (especially if I want to get down to lager temps). I’m no engineer, and kind of a hack, so let me know if I’m off my trolley with this…

So if I’m following you, you want to have the fridge and the fermentor enclosure separate? Using duct work, you’ll carry over the cold air to the box where the carboy is?

That’s what I’m thinking… that way, the small fridge could run constantly, chilling water bottles, storing cold… instead of a small fridge connected to the chamber having to kick on intermittently to cool a big chamber (if I had it all as one unit).

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Honestly I’m just thinking of a few things not to put down your idea… I think it’s a good one… but,
1:How much is your time worth
2:How much are you going to save when considering the time to build, the cost of materials for the project
3: Additional equipment you will still need even if you were to convert a chest freezer into a fermenting chamber
4:Building a chamber that will hold the cold
5:The possibility that if this didn’t work out so well, that you would have to spend even more money and time building another unit.

I still think the fridge is going to battle to keep the other chamber cold unless it’s super insulated… ASSUMING IM VISUALIZING THIS CORRECTLY.
Trust me I’m totally down for thinking outside the box so don’t think I’m knocking your idea

Totally looking for this kind of feedback. I probably should throw together a build sheet to compare against just getting a new 3 cf chest freezer… I do tend to do a lot of funding over 30-40 bucks difference.

If you really wanted to DIY I would build an insulated box using 2 1/2" polystyrene and cool using a window AC. All you would need to do is over ride the thermostat. This could be done by using something warm just on the probe (small light). You could then use it to cold crash as well.

If you can gather the material for cheap than go for it, but I think your better off with a craigslist chest freezer and a $30 inkbird temp controller…IMOP

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That’s fair. I have the temp controller. Used chest freezers have been running $100 for oversized clunky ones around here, for some reason, so a new right-sized one at $160 kind of makes sense. The $25 dorm fridges look so tempting, in comparison.

Her is a pic of idea for you also look up son of fermentation chamber. You can with add mini fridge to it.


I believe I’ve also seen similar things built on Brew Your Owns web sight…:beer::beer::beer:

Ok build a box. Put foam on the inside. A basket with ice. Open your fridge cooling system atach a coper pipe. Make a coil. Run this true the ice basket. And a computor fan. This should keep the fermenting box. Cool. Or find a old airco. Run the coil true the fermenting chamber.

I’ve seen Damian’s idea before and probably more efficient than what your thinking of but to be honest I would get a used fridge people are always upgrade ing.

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I like the idea for ales but I would seriously question whether the mini frig would get the 2nd chamber down to lagering temps. They don’t have nearly the cooling capacity of a larger frig or chest freezer. I’m only guessing here. Note that the running fan would add a little heat to the system too. I managed to secure an old full size frig for free. A friend was upgrading his kitchen and needed to get rid of it. Worked out well for both of us…

Just a thought. Have you considered putting the fridge above the chamber and allowing the cold air to simply sink into the chamber?



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I thought about that… cool air falling, and a warm air return in the opposite corner. My biggest concerns are price and space. I think I may be able to find a 3 cf freezer for a hundred bucks, which might be the best compromise.

I think that is your best option getting smal freezer too but here is link if you want to diy;_ylu=X3oDMTE0Z2t0bDJvBGNvbG8DYmYxBHBvcwM1BHZ0aWQDVUkyRkJUM18xBHNlYwNzcg--/RV=2/RE=1486804183/RO=10/

I built one of these back when I first started brewing back in 99. I wanted to stay cheap had a dorm fridge already I of course made some changes and added the dorm fridge closer to the top of the box since cold air falls and hot air rises. I did use the computer fan hooked to thermostat at the bottom and didn’t but the partition part of the plan with the dorm fridge.

hhhhhmmmm… Would you use a hydro recirc? Seems you could, a container of water in the fridge, small pump in the container, thru a copper coil on/in the container/wort… Sneezles61

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