36 replies to this topic

[Given2fly]

I've been putting this project off for years because fermentation temps have never been a problem for me, but now that I've got a bourbon barrel, a few of us plan to brew some larger batches later this summer. We intend on brewing two 25-30 gallon batches, which we all know will put off some major heat in the primary. Coolers and swamp buckets aren't going to cut it. So my plan was to use my old kegerator (basically a small dorm fridge from my college days) as the source for cool air and build a bunker. The key is to make the bunker large enough to fit the 25/30 gallon barrels, but airtight so that the fridge is not running constantly to maintain the temperatures needed. The dedicated space for the bunker sits in the basement (a room off of my bar) and typically is 60-65 degrees year round. I will most likely put a Love Controller or Ranco on the fridge (plus a fan to circulate the air), but will wait till I'm finished and the box is up and running before making those decisions. The inside of the bunker is lined with a mildew/mold resistant plastic and is completely sealed. So, here is the progression of the build for those interested. Anyone else build something similar?

[BarelyBrews]

I have dreamed of something like this.Looks like a great project.Keep the pics coming.Would like to see it when its all filled.

[ChefLamont]

I hate to be negative, but I am a little skeptical that the dorm fridge will be able to maintain any significant delta-T in that space. I really hope I am wrong. That would look great.Have you considered an AC unit instead of the fridge? That is what I have on mine and it works great. The only real problem I have is with the high humidity we have here.

[Rick]

Given2fly, looks pimpin buddy! Let us know how this bad boy works.I made something like this but on a smaller scale and used a much smaller dorm fridge (~2.5 cuft). I took one of those 8' x 4' pieces of 2" foam insulation and built a box that was just a tad larger than the opening of the fridge. The box was held together with foam adhesive and insulation tape. Then I wedged the box into the fridge opening then taped around the joining area to make make it as airtight as possible. I then adjusted the thermostat on the fridge to keep an air temp around 45 in the box and had a fermbelt hooked up to a Ranco that I wrapped around the bucket/PET bottle to keep fermentation temp within +/- 1 degree F. Worked like a dream and the fridge cycled just a couple times more times a day than it did when it was bottle storage.

[Given2fly]

I hate to be negative, but I am a little skeptical that the dorm fridge will be able to maintain any significant delta-T in that space. I really hope I am wrong. That would look great.Have you considered an AC unit instead of the fridge? That is what I have on mine and it works great. The only real problem I have is with the high humidity we have here.

I won't shit you, I am a little worried that the fridge won't put out enough cold air (although it is a kickass little fridge)...but we'll see. I'm hoping that I'm able to maintain consistent temps with the environment that the box is in ~63 degrees ambient and with a fan helping to circulate the air. I won't really know until I finish up the build and let it run for a few days. If the fridge is a bust, then I will most likely move to an AC unit (which I have in the garage)...but we'll wait and see on that one.

[SchwanzBrewer]

I won't shit you, I am a little worried that the fridge won't put out enough cold air (although it is a kickass little fridge)...but we'll see. I'm hoping that I'm able to maintain consistent temps with the environment that the box is in ~63 degrees ambient and with a fan helping to circulate the air. I won't really know until I finish up the build and let it run for a few days. If the fridge is a bust, then I will most likely move to an AC unit (which I have in the garage)...but we'll wait and see on that one.

I was going to do one of these too, but im still gathering equipment for other brew stuff so its low on my list. I was going to go with the AC unit route. They are inexpensive and with that little volume, can get down to lagering temps easily from what I have read.Cheers,Rich

[3rd party JKor]

I'm in the process of building my ferm chamber as well. It's probably about twice as big as yours (6'x6'x2' exterior dims), it's designed to hold about 20 cornies and two 15 gal fermenters. I'm going to use a 5,000btu AC to cool it.I have the same concerns as Chef on the ability for the fridge to extract enough BTUs. Any idea what the BTU rating on the fridge is? How about the continuous current? I think the continuous current on my 5,000btu is about 5 amps, the fan probably takes up an amp or two, so maybe 3-4 amps for the compressor. Assuming roughly similar btu numbers between an AC compressor and a fridge compressor, you should be getting about 1500 btu per running amp.I think maybe if you're just trying to maintain a set ambient temp it might be OK, but it's better to control the chamber on the actual liquid temp. I just insulated my existing chamber (which is just big enough for my conical) and when the AC kicks on to cool things down the ambient temp in the chamber can get down to 10°F. If you need quick cooling, you want a big delta T. I don't think the fridge will do that. That's just a guess, though.

[djinkc]

I won't shit you, I am a little worried that the fridge won't put out enough cold air (although it is a kickass little fridge)...but we'll see. I'm hoping that I'm able to maintain consistent temps with the environment that the box is in ~63 degrees ambient and with a fan helping to circulate the air. I won't really know until I finish up the build and let it run for a few days. If the fridge is a bust, then I will most likely move to an AC unit (which I have in the garage)...but we'll wait and see on that one.

That was the first concern I had too. You're talking about a big thermal mass that's generating heat. Hope it works but I would try to make the build so a Plan B wouldn't be to tough to implement.

[Humperdink]

You all may want to go to wort o matic and look up knewshound builds the beast. Its a project I worked on with a buddy where we built a two temperature zoned fermentation chamber that was run off of a dorm fridge. He'd had some fantastic results using that system.ETA: Clink

Edited by chriscose, 14 May 2010 - 11:32 AM.

[ChefLamont]

You all may want to go to wort o matic and look up knewshound builds the beast. Its a project I worked on with a buddy where we built a two temperature zoned fermentation chamber that was run off of a dorm fridge. He'd had some fantastic results using that system.ETA: Clink

I very well may be eating my words. That's impressive.

[Given2fly]

You all may want to go to wort o matic and look up knewshound builds the beast. Its a project I worked on with a buddy where we built a two temperature zoned fermentation chamber that was run off of a dorm fridge. He'd had some fantastic results using that system.ETA: Clink

Thanks for the link Chris, this makes me hopeful that the fridge will work. Hope to do some trials runs next week, will post results, pass or fail.

[strangebrewer]

So how is this project moving along? Run into any snags? Is it performing as well as anticipated? I'm planning to build something similar in the near future so I'm reading up on all I can find.

[Howie]

I'd also like to hear more. I have two small wine fridges now out in my little shed. They are really only big enough to hold one 6 gallon better bottle or one corny keg at the time. I think making something like this would take up roughly the same amount of floor space, but give me a lot more fermenting space. I'd love to make it big enough to hold some type of bigger fermenter (I'm thinking a half barrel Sanke).

[Given2fly]

Sorry, have been out of town for the week and didn't want to run the fridge while I was gone. I need to make a few modifications to the door and then will post results of it's trial run.

[Howie]

Sorry, have been out of town for the week and didn't want to run the fridge while I was gone. I need to make a few modifications to the door and then will post results of it's trial run.

How about some completed pics?

[Given2fly]

How about some completed pics?

Well, the outside is not 'complete' yet - still need to add the trimwork (want to wait to see how the fridge performs). Here is a pic of the door added...Put a thermometer in the bunker last night and the inside temp sits at 64 degrees (there's also a carboy filled with water sitting in the bunker). Started up the fridge this morning and will post results as the fridge starts to cool things down.

[Howie]

Well, the outside is not 'complete' yet - still need to add the trimwork (want to wait to see how the fridge performs). Here is a pic of the door added...Put a thermometer in the bunker last night and the inside temp sits at 64 degrees (there's also a carboy filled with water sitting in the bunker). Started up the fridge this morning and will post results as the fridge starts to cool things down.

Looking good. I'm liking this idea. I'm kind of thinking of a hybrid design something between yours and what this guy did with his dorm fridge. While I like the idea of yours, for roughly the same space I'd rather keep my two separate fridges two have two temp controls. I just want one to be a little bigger so it could hold two better bottles or one sanke. I only need to extend it out about 10-12" to get it to hold two better bottles.

[Given2fly]

Been a little over two days now and the temp is currently at 54 degrees (down 10 degrees from the original 64 degree temp). It is still slowly dropping in temp, just not as quick as I had hoped. Good results so far in terms of fermenting regular 5 gallon batches, but if I don't see temps drop more, then I may have to resort to plan B when it comes to fermenting the larger batches.

[SnailPowered]

Did you put any foam in the bunker? I had a room here in Iraq that was insulated with spray foam and it got down right frigid in there. I would think that if you aren't running some sort of insulation then you are absorbing a lot of energy the little fridge is trying it's best to cool off. If you spray a layer of spray foam in there and then wet it down it won't expand as much. It will take a lot more spray foam to get the job done but I would think that you would have something that transferred almost no heat to the interior...and was virtually bullet proof but that's another subject entirely! Good luck!

[3rd party JKor]

Did it take two days to get to 54, or is that just where it stabilized?For a point of reference, my ferm chamber (~2'x2x'5' w/5000btu AC) gets down to 10°F in like 15 minutes.