Fermentation Chamber Options

October 13,2010 by 31 Comments

Do you think Eskimos lager in igloos?

Just how important is your fermentation temperature in homebrewing? I came across a startling result from an experiment reported in the new homebrewing book Yeast, by Jamil Zainascheff and Chris White.

Chris White is the President of White Labs, a brewer’s yeast manufacturer. White Labs conducted a study in which two of the exact same ales were brewed, except one was fermented at 66°F and one at 75°F. They then tested for the difference in flavors.

Most of the flavors that we’d consider “off-flavors” showed a moderate increase, but what was really startling was the increase in acetaldehyde, which gives beer that green apple flavor. Its concentration was 8ppm in the 66°F beer, but 152ppm in the 77°F beer. So a 9 degree increase in temperature, but the acetaldehyde was 19x higher!!

Controlling Fermentation Temperatures

I’ve known for some time now  that fermentation temperatures are important, but over the past year have realized just how important they are. Examples like the one above, plus other information in this book, advice from other brewers, and most importantly, my own experience has taught me that if you want to make the best beer possible, you need to nail your fermentation temperatures.

But that requires equipment.

Putting the carboy in the back of your closet and praying isn’t going to cut it. Even if your house stays at a cool 66°F, during the height of fermentation your beer can easily go up 10 degrees because of the exothermic reactions. And 76°F is going to produce more flavors that will rob your beer of a clean taste.

The good news is that most of these flavors are produced during the first 72 hours of fermentation, so you don’t need to maintain the cooler temperatures the entire time the beer is in the fermenter. In fact, it is beneficial to let the temperature rise after fermentation so they yeast can fully attenuate and clean up some of those flavors produced during the height of activity.

Those first 72 hours is where the magic happens though, and we need to make sure we hit the correct temperatures.

Fermentation Chambers

Temperature control gadgets truly run the gamut in the brewing world. From a chilly corner in a homebrewer’s basement, to glycol cooling jackets on a commercial brewery’s stainless steel conical tank, to everything in between. When it comes to controlling temperatures, there is certainly more than one way to skin a cat, but I’m going to look at the most practical options for homebrewers.

Swamp Cooler

The swamp cooler is one of the cheapest and easiest ways to cool your fermenter. There are a few different swamp cooler variations. Most consist of a container to hold water and require the brewer to continuously rotate frozen water bottles for cooling.  A t-shirt over the carboy can be used to draw water up, and some people point at fan at the fermenter to get the evaporative cooling effect.

As you can read in my swamp cooler experiment, keeping consistent temperatures is the biggest problem. Large temperature swings are inevitable unless you are able to rotate bottles in every few hours. Even if you had that kind of freedom it would be a pain in the ass.

A more advanced swamp cooler I’ve seen uses an Igloo cooler with a foam top. This is a huge improvement because insulation is the weak point of the swamp cooler. YooperBrew over on HomebrewTalk has has one of these swamp coolers which she calls “The Lagerator”. This is a future project for me.


  • Good way to combat the heat of the summer

    Swamp Cooler

    My cold water bath style swamp cooler

  • Ability to get beer to ideal temperature range
  • Cheap


  • Labor intensive because you must frequently rotate out frozen water bottles
  • Difficult to maintain temperatures
  • Lagering is very difficult

Son of a Fermentation Chiller

This contraption is one of the most common homebrewer DIY projects out there. Commonly referred to as the “Ken Schwartz Son of a Fermentation Chiller,” it seems that Mr. Schwartz originated this thing.  Here is his document which is often referenced for plans.

How does it work? Schwartz say it best,

The Fermentation Chiller is an insulated box which uses ice, a thermostat, and a small fan to accurately regulate the temperature of a fermenter. While simpler insulated boxes and other simple temperature-management techniques often work reasonably well, they can’t regulate the temperature; they can only cool to “some point” below ambient, which changes as the ice melts.

So basically, you place gallon jugs of ice into the “ice chamber” and when the thermostat says it is time for cooling mode, the fan cuts on and blows cold air into the fermentation chamber until it is at the desired temperature.

Son of a Fermentation Chiller

The chambers of a Son of a Fermentation Chiller

Pretty nifty.

The obvious drawback about this is the work involved. The other is that it still involves rotating bottles of ice, but it is much more infrequent (every couple of days) vs. the swamp cooler (every few hours).


  • Cheap (~$70)  compared to a freezer or refrigerator
  • Small footprint (2’x3′) and lightweight
  • Very low cost of electricity


  • A bunch of upfront work needed, not to mention craftsmanship and tools
  • Requires exchanging of ice
photo credit

Chest Freezer/Refrigerator

For those looking for a more automated approach, you will want to go with a chest freezer or cooler. I personally prefer chest freezers because their design makes them more energy efficient (the cold air stays inside when the door is open). Their drawback is that it takes more lifting to get fermenters inside.

Chest Freezer Fermentation Chamber

Chest freezers are pricey, but a great option

These devices must be used in conjunction with a thermostat to control the temperature, which usually cost between $60-$100. Prices for the chest freezers vary based on size and condition. You could easily find a small cheap one on Craigslist for $50, or pay $400 for a large brand new model. The added benefit of this option is that they can double as kegerators. That’s a big plus in my book


  • Very little construction and maintenance involved
  • Keeps the most accurate temperatures
  • Can double as a kegerator


  • Expensive ($100-$300 for the appliance and $60-$100 for the thermostat)
  • Large and difficult to move alone
  • Higher electricity cost
photo credit

Temperature Controlled Conical Fermenter

At a starting price of $1,800, I’m not going to give much attention to these. Just revel in its awesomeness for a minute and think to yourself, “One day…”

Conical Fermenter

We're not worthy!

So where do I stand in this sea of  options? Unfortunately I’m not as sophisticated as I would like. I’m still using my ole’ blue tub as a swamp cooler, which allows me to mitigate high temperatures, but not get the consistency and accuracy that I would like.

The chest freezer fermentation chamber is my goal. Since mine bit the dust on my move to Denver, I’m watching Craigslist like a hawk for a good deal. Once I find one, you can expect a full report on how it turns out.

Do you practice temperature control on your fermentations? What do you use?

About Billy Broas

He is the founder of The Homebrew Academy, a BJCP beer judge, and the homebrewing expert on the Rocky Mountain PBS television show Colorado Brews. He lives in the fine beer town of Denver, Colorado.

31 responses to “Fermentation Chamber Options”

  1. I use the swamp cooler method, which works pretty well. I live in South FL, so the temperatures are high year round. I try and keep my apartment around 75F, so using a large tupperware container, filled halfway with salty water and 6 16.9 fl oz bottles of frozen water, tends to keep my fermentation temperatures around 66-68F if I rotate the bottles every 6-8hrs. Luckily, my wife is in grad school, so she can trade the bottles during the day, and I trade them at night.

    After primary fermentation is complete, I try to keep the beer around 70-73F so the yeast can continue to clean up the beer. Billy, do you think that is too high after fermentation is complete?

  2. OtownPyle says:

    Yeah I follow the swamp cooler method, like you showed on your site a few months ago, referenced above. I’m just looking for the right timing and a good deal myself as well.

  3. Jim Lavin says:

    I’ve tried several of the methods mentioned and by far re-purposing a refrigerator or chest freezer worked the best for me. However, when you start to get into some serious brewing, you end up needing at least 3 units. One to handle ales, a second for lagers and a third for storage. I don’t know about you but my garage is too cramped to handle 3 chest freezers.

    That is why I went a totally different route and started building out a cold room to store everything in. There are several great examples on the web. When completed I’ll be able to control the temps for fermenting beers and have room for storage.

    Also, building something for the home brewery from scratch is always a fun project!

  4. Jorge says:

    Excellent post! I talk a lot about keeping temperature constant during fermentation and getting equipment to control temperature before upgrading any other equipment…

    I personally use a wine cooler fridge, which I picked up for $130… although I’m thinking of getting a freezer so I can brew more than one batch at a time…

  5. Brett says:

    Swamp cooler being a pain in the ass is right! I am still living with my parents, and my mother is wonderful enough to swap out bottles for me during the day, but still the temp swings are a problem. I have an old mini fridge I am planning on building an insulated box to attach it to. If I only had a truck and the extra space in the house – I have seen a number of good refrigerators for $50 on craigslist the past couple of days!

    Also, I am going to be making the temp controller as seen on HBT’s “Ebay Aquarium Temp Controller” thread. I have trouble finding a balance between saving money, and having the joy of doing something myself! But ultimately, I cannot wait until i have an automated fermentation chamber setup!

  6. Billy Broas says:

    @John Yea if you have someone to help you the swamp cooler method can work really well. Sometimes I’m out of the house for 10 hrs at a time with no one to help so it becomes a problem. About your question, I think 70-73 is great for cleaning up the beer and you could probably go higher without having any ill effects. That book I mention talks about letting the temp get up to the mid 70s for ales not only to clean up off flavors but to make sure they fully attenuate. For lagers I think they say let it go to 68F for the diacetyl rest. It’s the same idea though – warmer temps at the end of fermentation. Thanks for the comment.

    @OtownPyle Man they go fast on CL. I’ve called a few people they day the post and they’re gone already. Might try yard sales too. Then there is the issue of fitting it in my Elantra..

    @Jim Excellent point about all the different chest freezers you would need. That’s something I’ve been struggling with in my mind. Even for your ales that are fermenting, you’ll want your fridge at different temps depending on how far along the beer is. For one at high krausen you might want your fridge at 50F to combat the high temps but for a beer that has calmed down, 50F would bring it down too far. Ah decisions decisions…

    A cold room though – Hell Yea! That should have been after the conical on the list. Do you have a link you can provide for someone looking into it? Also, how do you handle different temperature requirements in the room? Do you have sections that are colder for lagering? Really appreciate you stopping by and sharing.

    @Jorge I’m with you on that – temperature control is probably more important than going all-grain. A wine fridge eh? Hadn’t thought of that. Let us know how the freezer project turns out since it looks like a few of us are going that route.

    @Brett So right about it always being a balance between money, time, and the fulfillment of DIY. I think I saw a HBT thread about what you mentioned – basically expanding a fridge with an insulated box and using it for the cooling power. Another good idea, especially if you get a cheap (or free) mini fridge. Thanks for the heads up about the aquarium controller too, I’m gonna set aside some time to read through that thing.

  7. Thile says:

    I use the swamp cooler method as well. I am able to keep it around 68, with a little drop for the time I have the ice bottle in there. I think it peaked out around 70 – 72 during the height of the summer. I do keep the house cool, set on 72. Unfortunately the side of the house I use, probably gets the hottest in the Mississippi summertime.

    @OtownPyle and I have both been looking for other options. He watches CL more than I do. I’m about to start putting back a few dollars a month to move towards fermentation, then kegging, then all-grain. Although I’m not sure about how high a priority it is to move to all-grain. I don’t foresee a need to have a lagering chamber so should maybe work towards the chest freezer option.

  8. Bill Muneio says:

    Just finished building the “Son of a Fermentation Chiller” It was actually pretty easy and fun to build I’m pretty excited to brew my next batch.

  9. Billy Broas says:

    @Bill Hey Bill I’d love to hear more about the SOAFC. Got any pictures we can check out? About how long did it take to make? It seems like a fun project. I’ve also seen people get really creative and turn it into a nice piece of furniture for the house. Thanks the comment!

  10. Bill Muneio says:

    Hey Billy there’s some pics here (http://picasaweb.google.com/Bill.Muneio/SonOfAFermentationChiller?authkey=Gv1sRgCI_szvjH4deXEw&feat=directlink). It took me about 3-4 hours I guess, it’s pretty simple. I basically followed Mr. Schwartz’s plans the only thing I did different was instead of using dowels to hold the 2 removable panels in place I used some Velcro and nylon webbing, this seems to work pretty good it allows you to really cinch it up tight. I got most of the materials from Home Depot, but they only had 1 1/2″ sheets of foam so I glued that and a 1/2″ piece together to get the desired 2″ thickness also in addition to the adhesive I used some 3″ deck screws with fender washers to help hold things together (just tighten them lightly) I ordered this thermostat (http://www.amazon.com/gp/product/B000WEOQ6I/ref=oss_product) from Amazon because I couldn’t find one cheap enough at HD and that should be here tomorrow hope it works? The fan I pulled from a dead PC. I think my total cost was about $60.

  11. Billy Broas says:

    Wow Bill that’s one impressive piece of equipment. And only $60 & 3-4 hours? Nice work! I you’re going to see a huge return on your investment with the quality of beer you’ll be churning out. Thanks for sharing, I’m sure other people (including me) will be inspired to make their own now.

  12. Bill Muneio says:

    UPDATE: Just installed the thermostat I ordered from Amazon (Honeywell RTH111B). Followed Mr. Schwartz’s electrical diagram and it works perfectly :) Pic here: http://picasaweb.google.com/lh/photo/2lfQLk_I_0eOJSDBTDqlgSBCQMrIF9g3wF5tZaNU7Lw?feat=directlink

    PS It really is an easy project. The only tools required were a jig saw, a screwdriver and a caulking gun.

  13. Jason Harris says:

    I am running two different freezers now, one for fermentation and one for serving. I scored a full size stand up freezer off Craigslist for $100 that has room for four carboys. Just added a chest freezer that should hold 4 kegs once I add a collar. I work long days and it gets above 80 in my house during the day, so the other options are not too feasible for me.

    Luckily, now that the money is spent, my system won’t require much for maintenance.

  14. Billy Broas says:

    @Bill Glad that thermostat works well. I’ve got it bookedmarked on Amazon. Very cool looking too.

    @Jason That’s a nice set up, and is similar to what I’m headed towards. So in your stand up freezer do you use a shelf to fit all of the carboys? I don’t think I’ve mentioned it, but shortly after I posted this I found a ~ 10 cu. Ft. chest freezer for $50. My first priority is fermenting, but since I already have a kegging set up I want to get back into that. The goal is to go your route and have a dedicated chamber for each. Or maybe someday I’ll actually have a couple temperature controlled conicals. Yea, right….

  15. Steve says:

    I’m lucky to have a dad that manages to always get free stuff. He picked up a chest freezer that can hold 5 kegs and a mini fridge. I’m going to rework the mini fridge into a fermentation chamber for ales and I’m going to use the chest freezer for lagering. My real dilemna is whether to use it for lagering or kegging but since there’s no budget for kegging supplies right now it gets to be a lager cabinet.

  16. Billy Broas says:

    Hey Steve, way to go with the free chest freezer hookup. Alright Dad! I was struggling with the same decision with my existing chest freezer – fermenting or kegging. Since it’s used a little beat up I’m buying a new one for kegging, as described in this post: http://billybrew.com/kegerator-build. I’m running out of floorspace fast though. Thanks for the comment!

  17. Jay says:

    I use the upgraded version of the “Son of Fermintation Chiller” seen here:


    It worked great on my first two batches when the highs were in the mid to high 80’s and the back of my garage (dug into a hill) which stayed in the 70’s. Right now it’s 80 in the garage and 100+ outside. I’m trying to ferment my first all-grain wit and, at last check, it was at 70 with a goal of 67. I have no doubt the cooler can get these temperatures but, I need at least 24hrs for the blocks of ice to freeze. I plan to skin it out with some nice paneling so the wife will let it in the house for next summer.

    • Billy Broas says:

      I’m going to build one of these next month and might go with the upgraded version. Let me know if you have any pictures of yours. Sounds awesome.

  18. Caleb says:

    Hello, I just finished a fermentation chamber and was wondering what other methods might be out there when I read this.
    For mine, I got a $20 mini fridge off craigslist, removed the door, and built a foam box onto the front of it. I found some 2″ thick foam on the road that must’ve fallen off a truck or something. I made a sort of lap joint to the front of the fridge by carving the foam and then held the five sides together and onto the fridge with four ratchet straps.

  19. Brian says:

    My friend and I are getting into home brewing. We have brewed our first batch, and it is in fermentation. We put it in my basement bathroom. The temp in there is a consistent 61-62F. We also wrapped a blanket around it to help warm it up a little more.

    My question is with the SOFC if you are in a colder climate like we are (Michigan) how would it warm up the cooler if it needed to?

    • Billy Broas says:

      Hey Brian, the SOFC doesn’t heat up, at least not in the original designs. You could modify it to heat though. You would need something like a heat lamp or brew belt: bit.ly/VKTgnY

  20. Cory says:

    The best and easiest way I have found to get your dual temperatures for lager and ale is by converting a chest freezer and placing a thermostat on the side with the evaporator coil. This will let you control the temperature of that side to a lager temperature and then by creating a hybrid of the son of fermentation chamber with a small fan on a 2″ foam divider connected to a simple mechanical thermostat to pull the colder air from the lager side to the ale side. It works like your home refrigerator where the freezer is the only part that is actually cooled and it just pulls whatever amount of cool air you need to make up the difference. Nice thing about this setup is that you can take out the divider and use the whole thing for lager or ale if you are doing a bigger batch of one or the other. I have a 15 cubic foot freezer someone was throwing away because it “didn’t get cold enough” and I can fit 3 carboys in each side or 6 for a full load. (never done one full load)

  21. Jon Styre says:

    Hey guys, Here’s a question that I can’t find an answer to anywhere. Just brewed my first batch last Sunday. Carboy is fermenting in a 7 ft3 chest freezer with an external Johnson Controls thermostat. Do I need to vent the freezer to let the Co2 escape?

    • Billy Broas says:

      Hey Jon, you don’t need to vent it. It really doesn’t produce that much CO2. If you’re worried about it you could simply lift the lid every few days. It does tend to collect around the bottom so if you lean in there for some reason, hold your breath. It’s not too pleasant ; )

  22. Ben says:

    I just finished up a method that I use my chest freezer to chill water and then use a temperature controller to pump the cold water through a stainless immersion coil in my fermenter. I already keg beer so all I needed was the pump and coil and another controller. This allows me to keep beer cold for serving and keep my fermentation temperature under check. I would mention that I brew 15.5 gallon batches and ferment in a 33 gallon stainless open fermenter that my uncle gave me. So fitting that in a chest freezer was not going to happen very easy. I am going to insulate the fermenter soon with http://www.zorotools.com/g/Insul-Sheet%20S2S%20Insulation/00069515/ to allow me to lager in it. Cheers!

  23. Stuart says:

    I moved from a house to an apartment (hopefully it’s not permanent) and bought a CoolBrewing (https://www.cool-brewing.com/) refrigerator bag for about $55. It folds down when not in use and I was finally able to brew my first lager after 8 years of brewing only ales. It requires more work to maintain desired fermentation temps than a chest freezer though. After cooling my wort, I placed a pre-frozen gallon of water and a 20 oz bottle of frozen water inside the cooler to keep my German Pils at 50 degrees and switch it out with another frozen gallon of water about every 10-12 hours. It’s not perfect, but it has allowed me to brew a lager, while still dreaming of a chest freezer in the future. Next up is a Maibock for my birthday, which is May Day!

  24. Todd says:

    I liked your post of the different methods of fermentation temperature control and appreciate the link to the chamber build. Something I would like to build but I have a question or rather an idea;
    I wonder if it would be possible to build a chamber that utilized a thermowell (readily available through various home brew supply companies for plastic and glass carboys) and a low price temperature controller like the stc 1000 or the DC 12V Digital Temperature Controller I saw on Amazon (which is basically a DC version of the STC1000) to control the fermentation temperature more accurately ?
    What are your thoughts on this ?

    • Billy Broas says:

      Hey Todd, you could use any controller. I just bought an STC myself to play around with. Cheers.

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