Building a Fermentation Chamber

I have been brainstorming how to build a fermentation chamber for quite some time now. I want to have reasonably high output (8, six gallon carboys) with the option of fermenting two different batches at two different temperatures. Given these parameters I have come to the realization that it may be easier to build a custom refrigerator from scratch.

I have seen DIY projects where people cut doors and ceilings off of old refrigerators and built around them to make a larger storage space. I have considered this, but I am leaning towards building a unit from scratch because of the ability to customize the unit to be exactly what I want. I was wondering if anyone has ever taken on this project before. I have researched on the internet tirelessly to try to find information on how to build a fridge and I've found some useful information, but it seems very limited. I am planning on going to an appliance parts warehouse this weekend to discuss the project with their associates to get further insight, but I wanted to know if anyone else has tried and/or succeeded in a similar project.

I know that once I build the insulated box I need a compressor hooked up to the steel or copper coils, with an expansion valve, and obviously the coolant inside. Are those the only major parts? Any help would be more than greatly appreciated. I know this is a rather complex topic, but it is a project that I've really wanted to tackle and I just can't let it go without giving it a shot. The ability to ferment almost 50 gallons of beer at optimal temperatures would be a dream come true....

It is possible but the problem is if the existing compressor and evaporator coils can efficiently transfer heat in a space larger than what they were designed for. Making a refrigerator larger than it is requires much more knowledge than the typical DIYer has. It can and has been done but then again those people wonder why their compressors never turn off and eventually burn out.

There are a few members here who have removed the guts of refrigerators, and re-purposed them in a heavily insulated boxes to create rather large fermentation chambers. I would think that would be much less hassle than actually building a fridge from scratch (since the condenser/evaporator system would be pre-fabbed).

Whatever you do, heed PurpleJeep's warning about overworking the compressor, and make sure that the heat load doesn't outpace whatever system you decide to put together.

PurpleJeepXJ said:

It is possible but the problem is if the existing compressor and evaporator coils can efficiently transfer heat in a space larger than what they were designed for. Making a refrigerator larger than it is requires much more knowledge than the typical DIYer has. It can and has been done but then again those people wonder why their compressors never turn off and eventually burn out.

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I am looking at buying a new 5 cubic ft. deep freezer that I found on Craig's List that is less than a year old. I would imagine the compressor on a deep freezer would have higher output capacity than that of a refrigerator comparable in size?

markd87 said:

I am looking at buying a new 5 cubic ft. deep freezer that I found on Craig's List that is less than a year old. I would imagine the compressor on a deep freezer would have higher output capacity than that of a refrigerator comparable in size?

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The output would probably be enough for what you're trying to do, but modern chest freezers have coils run throughout their walls. It's no trivial task to dismantle the walls without damaging the coolant and evaporator lines.

markd87 said:

I am looking at buying a new 5 cubic ft. deep freezer that I found on Craig's List that is less than a year old. I would imagine the compressor on a deep freezer would have higher output capacity than that of a refrigerator comparable in size?

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not necessarily. freezers and refrigerators both are mainly meant to keep what is inside cold (so mainly they just have to fight the small amount of heat leaking in thru the insulation, or from spradic opening of the door), and not to continuously remove a large influx of heat like putting tens of gallons of warm liquid in.

air conditioners on the other hand, are meant to sink LOTS of heat and to do it continuously. a typical fridge will have the capacity of 1000-2000 BTUs/hr. the smallest and cheapest air conditioners can do 5000. since you can often find perfectly working window air conditioners for almost free, thats probably a much better route. then all you have to do is get some rigid foam and build a box.

the energy requirements would be about the same, since both A/C's and refrigerator/freezers are all phase change coolers. the a/c would just be able to reach a temperature faster and the compressor would not need to be on as long. you do need to set the hysteresis band wide enough that its not constantly short-cycling, though.

Check out the Cool bot available at www.storeitcold.com . I don't own one or have an interest in the company, but I think it's a good indicator of what's possible with an ac unit.

The OP obviously has no idea how refrigeration works. I would say go ahead and build it and your compressor will wither burn out or your power bill will go up. Go get a book on basic refrigeration design if you want to build your own unit.

Thanks for all the input guys. I just randomly stumbled across a commercial freezer that I think should provide me with ample space (49 cubic ft.). Although it's well out of my price range I think am going to try to negotiate to get it down about 20% and hopefully just buy it since building one myself will still cost a pretty penny, but probably not be nearly as effective and take a fair amount of hours. I am still waiting to hear back from the seller, but I'm hopeful.

http://chicago.craigslist.org/nwc/app/2622530758.html

Greetings from Chicago!

I highly recommend going with an AC unit if you want to build something to purpose for multiple temperature zones. Especially if you're talking about using one compressor to cool two separate areas, I'd expect that an AC unit would do the job best because it has a big ol' fan in it pushing the cool air around. You'll need the fan in the AC unit plus some extra fans to move cold air from one zone to another. Besides, a 5,000 BTU AC unit can be had for next to nothing compared to a freezer.

Naturally, you won't have to build anything if you buy a freezer, but if you expect to be dealing with 50 gallons of brew in carboys and buckets or similar fermentation vessels, the dimensions of most commercially available chest and upright freezers and refrigerators won't be optimal. The space might seem sufficient, but the problem is how the space is laid out in most of them.

Here's something prrriiide did that really fits the bill:
Planning stages: https://www.homebrewtalk.com/f163/fermentation-chamber-build-222380/

Building stages: https://www.homebrewtalk.com/f51/fermentation-chamber-build-239480/

If you decided to go with refrigerators or chest freezers, it would probably be a lot easier to buy two and just set them for different temperatures.

Just my .02. Building a whole new refrigerator from scratch is for factories. Foam insulation sheets are relatively inexpensive and do just fine insulating.

ilikethetrees said:

Greetings from Chicago!

I highly recommend going with an AC unit if you want to build something to purpose for multiple temperature zones. Especially if you're talking about using one compressor to cool two separate areas, I'd expect that an AC unit would do the job best because it has a big ol' fan in it pushing the cool air around. You'll need the fan in the AC unit plus some extra fans to move cold air from one zone to another. Besides, a 5,000 BTU AC unit can be had for next to nothing compared to a freezer.

Naturally, you won't have to build anything if you buy a freezer, but if you expect to be dealing with 50 gallons of brew in carboys and buckets or similar fermentation vessels, the dimensions of most commercially available chest and upright freezers and refrigerators won't be optimal. The space might seem sufficient, but the problem is how the space is laid out in most of them.

Here's something prrriiide did that really fits the bill:
Planning stages: https://www.homebrewtalk.com/f163/fermentation-chamber-build-222380/

Building stages: https://www.homebrewtalk.com/f51/fermentation-chamber-build-239480/

If you decided to go with refrigerators or chest freezers, it would probably be a lot easier to buy two and just set them for different temperatures.

Just my .02. Building a whole new refrigerator from scratch is for factories. Foam insulation sheets are relatively inexpensive and do just fine insulating.

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Yea I kind of bailed on the idea because of the freezer I found that I mentioned above. I got the measurements and I think it should fit 16 six gallon carboys so it should be more than enough. I agree with your assessment though. It seems like the A/C unit would be the easiest route from everything I was reading. However, it would require more space which is tough to come by in Chicago.

16! Wow, that really puts mine to shame. Great find! : )

Someone posted a commercial fridge like that with glass doors in fon du lac wisconsin....I think price was 300. Don't quote me, check classifieds here.

EDIT: here is thread....

https://www.homebrewtalk.com/f16/fond-du-lac-wi-area-commercial-fridge-not-mine-271803/

An AC unit works well. I split mine and ran only the coolant lines into the fermentation chamber, instead of constructing a “window” in the chamber.

The small fan runs only when the heat/cool system is powered, to move the air around. Would like to put it on a delay but I don’t currently have the technology.

Heat provided with a terrarium lizard heater.

The controller is switched for heating and cooling operations. The unit is set for heat or cool but not able to do both as everything runs off the same controller.

I bought a large chest freezer on sale at Best Buy and got a digital temp controller online for around $50. Hooked it up and set for 65 degrees. Maintains from 64 - 66 like a dream.

Rick near Atlanta

Here's the fermenter fridge that I'm building. I brew with conical's, so I went with a glycol system, but if you wanted air cooling, it would have been easy to put the evaporator in the top half. For what it's worth, the old fridge has a 1500btu/hr capacity, and I've currently got it in the garage fermenting a lager @ 52 degrees.....with no door. (liquid cooled not air cooled)

I plan on getting the door done soon, then adding some form of radiator+fan to allow the air temp in the box to be cooled as well (if needed)

might give you some ideas

https://www.homebrewtalk.com/f51/glycol-fridge-fermenter-mod-build-268741/