DIY fermentation heater chamber for beer

by Daniel on January 27, 2012

my belgian (american) tripel happily bubbling at 70F

Keeping your fermenter at the ideal temperature for the yeast is extremely important to making a good batch of brew.  Living in Rochester, NY in an older house, the ambient temperature of my apartment rises and falls 10-15 degrees F on any given day.  The basement is much more constant, but generally too cold for fermentation (40-50 F).  What to do then to keep my fermenter right at 70 F when it’s cold?  Build my own garbage can fermentation chamber!

After researching many different areas, I found an extremely great solution.  Rather than buying a semi-expensive temperature regulator and plugging it in to a special heat wrap (or even more expensive adapting it to a spare fridge/freezer), I decided to purchase a 20 gallon Rubbermaid garbage can ($14 Home Depot), and a 50W submersible aquarium heater with temperature setting capability ($18 Amazon & free shipping – bought myself Designing Great Beers to qualify over $25).

a perfect 70F, all day, all night

Water is a fantastic insulator – having a very high heat capacity.  So by submersing my fermenter into a larger garbage can containing water (not over the brim of the fermenter of course) that is set to 70 F by my aquarium heater that uses minimal power, I’ve got myself a great way to control my temperature, for much less than it may otherwise cost!  Analog temp controllers by Johnson Controls run around $60 (for fridges), and digital ones are upwards of $80.  Plus, rather than controlling the ambient air around my carboy, I am insulating it with water, which will maintain a temperature much more consistently.  So far, the belgian tripel that I brewed on 2/4/12  has been extremely happy with it, and the temperature has not fluctuated from 70F during any time of day, while my apartment’s ambient temp has been rising and falling from 55F – 70F.

A note after using this for my primary fermenter the first time, and now my carboy for secondary: Leaving the lid of the garbage can unsealed & slightly cracked over the top is a good idea to prevent condensation buildup so things don’t get wet in there. Just better that it all stays dry, but it still will keep the sunlight out.

Happy brewing!  Check out my other easy DIY projects here.


{ 30 comments… read them below or add one }

Robert Orzel September 2, 2015 at 2:57 pm

A great idea. I followed your instructions. However, how do you prevent the 6.5 gallon fermenter from floating in the 20 gal garbage can?


Daniel September 9, 2015 at 9:13 am

As long as the water level is just slightly less than the level of the beer in the bucket, you’re good!


Sue April 4, 2015 at 2:44 pm

Daniel, would it be possible for you to post pictures of inside the trash can showing the position of the heater? thanks


Daniel April 6, 2015 at 10:39 pm

Thanks for the comment Sue! I generally just stick it to the bottom of the can with the suction cup mount that comes with the unit, in between the wall of the bin and the side of the bucket or carboy.


Logan February 17, 2014 at 1:40 pm

This is a great idea! And will definitely save me a lot of money! Although I seem to have the opposite problem as I live in Arkansas and need cooler temps in the summer time. However, before I try this, I just wanted to know if I could set the temp on the aquarium heater cooler than ambient temp in my house so it would actually cool my water instead of heat it?


Daniel March 8, 2014 at 8:45 pm

Hi Logan, unfortunately the aquarium heater will only heat the water, it cannot cool it. If you’re looking for something to keep things cool, get a chest freezer and build my DIY temperature controller for freezer/keezer! (


Dustin February 11, 2014 at 12:19 pm

Great idea. I think I’ll steal this next time I brew. I wonder if using distilled/filtered water would make it even more effective (lower conductivity than tap water), and if the few extra bucks would make it even worth it??


Daniel February 14, 2014 at 4:16 pm

Thanks Dustin, glad to hear you’re going to try it out! In my opinion, it wouldn’t probably be worth the extra cost for the distilled water. If anything, use the distilled for your brew if you want to change the water profile by adding your own minerals.


Leo December 2, 2013 at 10:53 am

I used this technique to finish out a saison. I brew 1 gallon batches and my bucket fits in a standard cooler. The cooler was in the garage and the heater held the water at 80-82 F! Thanks for the tip, now I can brew summer beers in the winter.


Jacques November 13, 2013 at 1:06 pm

Hi, Daniel. A buddy and I did basically the same thing last year when we started brewing in December here in San Diego. While not as cold as Rochester, it was too cold for our initial brews and not being experienced enough to pick beers that want colder fermentation (it was in the low 60’s in our “brewery”), we did a tub and a glass, tubular-type fish tank heater. We added a small fish tank pump to circulate the water and added a little bleach to keep it from getting nasty. It worked like a charm. Now that I’m brewing on my own, I will stick with this system, but get one of those trash cans. I use glass carboys for fermenting so it should fit great. Getting my freezer for cold fermenting today. Great blog, by the way.


Paul November 9, 2013 at 7:15 pm

Excellent post! Does your fermenter have a spigot at the bottom? Wondering if it is safe to submerge in water.


Daniel November 12, 2013 at 1:28 am

Thanks Paul, good question. No, I use a bucket without a spigot as my fermenter. It’s probably fine to submerge, but make sure you disassemble the spigot and thoroughly clean & sanitize it frequently to avoid buildup of microflora!


Leo November 4, 2013 at 10:14 am

Great idea and project! I just brewed a saison last weekend and it is a bit cold in my house. Probably should have brewed it a month earlier. Anway, do you lay down the aquarium heater on the bottom of the trash can or put it vertically?


Daniel November 8, 2013 at 12:19 am

Thanks Leo! I usually stick it to the bottom of the trash can.


KF September 30, 2013 at 10:37 am

So glad I found this idea. My wife was tired of my fermenters all over the house at different times of the year with blankets, and heat pads; straddling heater vents, etc… Now I can banish all of it back to the basement! I went out yesterday and got the can at HD for $13 and an aquarium heater for $24. This morning my gorgeous bubbling beast of an IPA brewed on Saturday is happily kraeusening away at 67.5° F – perfect!

I actually had built one of those insulated fermentation cabinets a couple of years ago with the false bottom, light, recirculating fan, and digital temp controller. Though it holds two fermenters, it just seems to run all the time. This idea my friend makes so much sense, and the aquarium heater barely kicks in.

Good stuff, man!


Daniel September 30, 2013 at 10:25 pm

KF, I’m so glad you found it, used it, and liked it! It’s getting to be the perfect time of year for this option, and it’s just so simple, affordable, and darn good at keeping consistent fermentation temperature. Good luck with the brews, I’d love to hear how they end up with your new-found setup.


Jason August 26, 2013 at 6:45 pm

I have just been using an old heating blanket to wrap around my fermenters. I can get it completely around 3, 6.5 gallon buckets or carboys. I put a wool blanket on the floor and it works beautifully! I also put my bottles under it to speed up the carbonation in the winter.


Daniel August 28, 2013 at 2:36 am

Thanks Jason. You’re right, that works great too, depending on the stability of the ambient temperature where you store everything. A lot of people do that with great success!


JC February 18, 2013 at 1:49 pm

Hello Daniel……..just ordered the same heater you have through amazon. I also bought my trash can yesterday at Home Depot. The heater came out to $22 but I bet it’s going to be worth it. Wish me luck!!!


JC January 10, 2013 at 7:02 pm

I really want to do this DIY but don’t know anything about aquariums and their heaters. I found this on Amazon…….

What do you think? It’s only $16.


Daniel January 21, 2013 at 12:57 am

This heater looks plenty sufficient. 50W is enough to heat 10 gallons – which is what you need because you’ve got 5-6 gallons of wort submerged in 5 gallons of water in the garbage can. The only forseeable issue that I can’t predict is whether this one in particular can be set low enough so not to overheat your beer. We often want to keep things at 68-70F for ales, whereas fish are more at the 75F+ range. I would guess however that your chances are better maintaining safe temps with this 50W version you found than a 100-150W or higher unit.


JC January 9, 2013 at 3:05 am

This is awesome!! Brewed my first 5g batch and it’s tasting like green apples. The bottles have been conditioning for over a month and still the weird taste. I’m sure it was the fluctuating temp in my basement room. It was pretty ridiculous. I’m gonna do exactly what you did to keep temps steady. Will a Brute trash can from Home Depot work OK? I would love to see you do some kegging projects for beginners and maybe converting a full size frig into a kegerator. Just a thought. Keep the posts coming!


Daniel January 21, 2013 at 12:53 am

Thanks JC! Yes, the Brute cans from Home Depot are awesome. As for the kegging project I do have a DIY kegerator using a chest freezer – just check out the “DIY Projects” link in the Nav menu at the top of the page. I like chest freezers better for kegging in general, you just have to make the temperature controller that I show you step-by-step. Keep the suggestions coming!


Daniel February 13, 2012 at 11:15 pm

I’m very happy to say now that after 9 days in my fermentation chamber, the temperature of my primary fermenter regardless of the ambient temp of my apartment has still been maintained at 69-70 degrees F. I couldn’t have asked for an easier and more affordable build or a better result!


Leslie February 7, 2012 at 8:24 pm

Love the blog


Daniel February 7, 2012 at 10:04 pm

Thank you so much! I am always looking for suggestions for subjects to post on. Let me know what you’re interested in and I’ll see how I can help!


Mike January 28, 2012 at 10:03 am

I built a wooden box for my fermenter, with a single light socket inside, depending on the time of year a 40w or 60w light bulb did was enough to keep the temp right. Of course you can’t use the “green” bulbs.


Daniel January 29, 2012 at 5:54 pm

Yes, this would work too, with some tinkering. It is important to note for other readers, that it is important to shield your fermenter from light. So if you use this technique, put your fermenter in a garbage bag, with a hole for the airlock to stick through.


Eric January 27, 2012 at 11:19 pm

Great idea, Dan! Water heat capacity is a guiding principle of our nuclear navy.

Do you think a wrapped moving blanket would have done the trick, too? I only say this as I had a near catastrophe smoking some pig for our last social – it was too darn cold to for the electrical head unit on my smoker to even cycle on, so I pulled the head unit off, cleaned the connectors and warmed the circuitry with a hair dryer…worked like a champ…THEN, my smoker would not maintain temp throughout the 25 degree night outside….so, I wrapped it in a POS old U-Haul furniture blanket. Kept the temp perfectly. Might do the trick decently with a fermentor in a temp-controlled (albeit cold temp-controlled) basement.


Daniel January 27, 2012 at 11:28 pm

Good question Eric. A moving blanket isn’t quite enough when the temp gets too cold, because the fermentation process isn’t exothermic enough to maintain its own temperature. If you’re indoor temp is warm enough, say 63F and you want your fermentation to be 65+F, you can probably pull it off with a good blanket. However, Rochester in the winter as you know from your own lake effect hometown gets darn cold–so I need a little something to keep the temp right without using up tons of gas leaving the furnace on all day. Big point to remember though: it’s not just the absolute temperature. To much temp variation, even if it’s in the acceptable range, can throw your yeast off.


Leave a Comment

Previous post:

Next post: