Water jacketed fermentation chamber

I have found that attempting to control the temperature inside my glass carboy by manipulating the temperature of the surrounding air (refrigerator) is not really providing the type of control I desire. For ales, during heavy fermentation stage my carboy temperature rises as much as 3 degrees above my desired setpoint. Lager control is better due to the much slower fermentation.

The trouble is that the heat transfer coefficient of a glass carboy in air is horrible (i.e the thick glass is a good insulator and does a decent job trapping in the heat from fermentation). At times heat generation for 5 gallons of typical wort can approach 50 - 100 Btu/hr. The heat has to leave through the thick glass into the cold air by natural convection.

I realize that I could ditch the glass carboys and move up to the big leagues with stainless conical, but my wallet isn't ready for the big time. That is why I am considering moving to a water jacket. Typically, the heat transfer coefficient is increased by a factor of ~20 if the cooling fluid is changed to water versus air. This will be my first step - determining the overall heat transfer coefficient for my glass carboy in both air and in water. If the difference is as significant as I expect, I will press on!

Anybody tried this water cooled idea with a glass carboy fermenter?

Technically, yes... in a refined manner, no. In a room with an ambient temperature of 75 deg, I was able to ferment close to 63 deg by placing the 5 gal carboy inside my ten gal rubbermaid cooler and adding ice to the water periodically (I would drain water out of the spigot when space was needed. I wasn't measuring the ice/water, but kept an eye on the wort temp. Probably would have worked better with a smaller carboy/larger holding vessel as the thermal mass of the water was fairly small (space around carboy was 3/4" - 1" on all sides).

Interesting stuff. I am already looking at possible containers for the water and I saw the 10 gallon rubbermaid coolers. I am surprised you had to hold the water temperature so low (~32F) to achieve internal temperatures in the 60's. This is worrisome. I would have guessed that the water would need to be controlled at around 60 to achieve a temperature of 63, even during heavy fermentation. But, that is why I am doing some simple experiments to determine the heat transfer rates for my good lo carboy!

I think you're looking for this...

https://www.homebrewtalk.com/f51/water-fermentation-chiller-81501/

Why not lower your set temperature point on the fermentation chamber 3 degrees? This would achieve the same result of holding your desired fermentation temperature.

jmansfield said:

I have found that attempting to control the temperature inside my glass carboy by manipulating the temperature of the surrounding air (refrigerator) is not really providing the type of control I desire. For ales, during heavy fermentation stage my carboy temperature rises as much as 3 degrees above my desired setpoint. Lager control is better due to the much slower fermentation.

Click to expand...

Really? I'm surprised to hear this. I have no problems with maintaining fermentation temps with a small chest freezer and an Ranco temp controller?

Maybe its the difference between how cold a refrigerator can get vs. a freezer? Also, where do you put your temp probe?

If you pay close attention to the actual wort temperature, inside the carboy, you will see that it rises quite a bit higher than the fridge temperature. The Ranco will try to control the temp by cycling the fridge/ freezer but it simply cannot pull the necessary BTU's out of the glass carboy (especially for fast fermentations). Typically you will see a rise above your setpoint of 3-5 degF and then after 4-6 hours it will undershoot the setpoint by a few degrees. Kind of an ugly cycle. I have found that the heat transfer coefficient for a standard glass carboy is ~ 1.0 BTU/(hr-F-ft2). Very poor.

Thanks for the link to the water chiller. I am thinking something similar except instead of ice change-outs I am planning to try some small refrigeration (like an aquarium chiller). I think this little item will do the trick - they call it the "ice probe". http://www.novatecproducts.com/iceprobe_aquarium_chiller.htm

OK, I have finished the experiments. This was much simpler than I was expecting. Basically I ran two separate tests. In the first set I started with my carboy with 5 gallons of 100 F water sitting in my cellar at 70 F. In the second set I started with my carboy with 5 gallons of 100 F water sitting in a tub of water tightly controlled at 70 F. From careful measurement of elapsed time and temperatures and using heat transfer principles I was able to estimate the overall heat transfer coefficient of my glass carboy. Here are the results:

Ucarboy, air = 0.97 BTU/(hr-F-ft^2)
Ucarboy, water = 9.82 BTU/(hr-F-ft^2)
Carboy Effective Surface area ~ 4 ft^2

So, the carboy sitting in water transfers heat about 10 times faster than a carboy sitting in air. In my experiment, the carboy in air took 37 hours to cool from 100 F to 71 F, while the carboy in water got there in less than 4 hours !!!

I would expect actual heat transfer rates during fermentation to be slightly better than what is listed above due to the natural agitation that occurs inside the fermenter. What is now clear to me is that if I simply submerge my carboy in water coolant that is temperature controlled I can safely assume that the carboy contents are within 1 degF of the coolant. This is because at a 1 degF difference between carboy and coolant you achieve heat transfer rate of about 40 BTU/hr - which is equal to the typical heat of fermentation at high fermentation rates. The same cannot be said for air cooling, only capable of removing 4 BTU/hr at 1 degF delta.

jmansfield said:

If you pay close attention to the actual wort temperature, inside the carboy, you will see that it rises quite a bit higher than the fridge temperature. The Ranco will try to control the temp by cycling the fridge/ freezer but it simply cannot pull the necessary BTU's out of the glass carboy (especially for fast fermentations). Typically you will see a rise above your setpoint of 3-5 degF and then after 4-6 hours it will undershoot the setpoint by a few degrees. Kind of an ugly cycle. I have found that the heat transfer coefficient for a standard glass carboy is ~ 1.0 BTU/(hr-F-ft2). Very poor.

Thanks for the link to the water chiller. I am thinking something similar except instead of ice change-outs I am planning to try some small refrigeration (like an aquarium chiller). I think this little item will do the trick - they call it the "ice probe". http://www.novatecproducts.com/iceprobe_aquarium_chiller.htm

Click to expand...

Truthfully, I don't see this with my system (at last I don't think so). I have the probe taped directly to the fermenter so the temp controller is monitoring the temp of the fermenter, not of the air around the fermenter.

I see your point about the fridge/freezer not being able to efficiently to pull heat from a an already active ferment, but I don't think this is as big of an issue when you have temperature control in place before fermentation has started. A vigorous fermentation is the result of a ramp up stage in the 12-24 hours preceding it and if you have proper temp control in place at that point, I don't see how fermentation activity could "get ahead" of temperature control as you suggest. Again, maybe it comes down to using a freezer vs. a fridge and the temp of the air coming out of the compressor between the two.

Practically speaking, even if my temp control isn't spot on, I haven't noticed any off-flavors as a result. Works for me (and others).

I guess everyone's system is different...carry on!

Broadbill, I totally agree, if you are happy with your homebrew then there is no reason to try to fix it. In my case, I used to measure temperature the way you do (surface temp of my glass carboy) and one day I decided to use a measurement in the center of the fermenter, in the wort. I was very surprised by the difference, and not very happy with the control performance. By looking at the surface temperature of the carboy you are getting a measurement that is heavily "filtered" or "smoothed" (if you are using glass or plastic fermenter). So it makes you think your control is great. Really appreciate your input, and like you said what matters most is the final product - don't fix it if it ain't broke.

Here is a photo of my water cooled fermentation chamber. It is pretty simple...just a 20 gallon trash can inside a 32 gallon can with great stuff foam in the gap for seal and insulation. I am using the "Ice Probe" which I purchased for ~$100. I have not made any beer with this yet but have done some water testing to see what type of control I can get. In this configuration you end up with about 5 gallons of coolant water plus 5 gallons of "beer" in your carboy (any more coolant water and the carboy wants to float). What I see is that the ice probe will pull about 150 BTU/hr when the liquid is at room temperature and about 80 BTU/hr when I am 10 degF below room temperature - this means I should get great control of ales (63 - 75 F). I let the probe run continuously for 4 days and it was unable to pull the temperature below 55 F, so this "Ice Probe" ain't gonna work for lagers!

interesting, waiting to here how it works with a fermenting beer.

It works great! I have made 3 batches and the results have been better than I expected. I have fermented at 70, 66 and 64. I have never seen the wort temperature get more than 0.3 degrees above the swamp water temp. I will never go back to the old fridge setup, this is too easy. Initial $ for the trash cans and the iceprobe was $130 and it is extremely energy efficient.

What if you had an extra corney in the keggerator filled with water, and used a pump to circulate the cold water through copper tubing 'wrapped' around the carboy, or a kettle for that matter? I've been trying to figure a way to control ferm temp in a kettle on the brewstand.

I don't get why glass and stainless are the only two choices you are considering for fermenters. What's wrong with an ale pail?

Layne - not sure what you are going for there - sounds like maybe you are space limited so you want to ferment atop the brewstand? I looked at the idea of getting cooling by running copper tubing inside my fridge but it seemed too complicated, needing a pump and a whole bunch of tubing to pull the needed 50 - 100 BTU/hr. If your brew kettle is large enough you can put your fermenter inside of it, fill the kettle with water and stick it in fridge -stick temp controller probe in the water. Fridge does a great job transferring heat out of the stainless brew kettle and the cold water in the kettle is 10x better than the cold air of the fridge at removing BTU's from the beer in the glass or plastic carboy.

Weirdboy - a plastic ale pail works too. I found that it has very similar heat transfer as a glass carboy, it is a very good insulator making it difficult to cool the liquid in the fermenter during rapid fermentation. Submerge it in a temperature controlled swamp cooler like mine and you will be very happy.

Yesh, I have this idea of an all in one, start to finish brew system. Just in the thought stage now, may have to abandon the idea, but it would be cool if it could be done.

Jmansfield - Are you still using that setup? What are you using a temperature controller? Is it built in to the ice probe? Do you have any plans to add warming for winter months?

I really like the simplicity of that setup. I might do that with a wider tub that can fit an ale pale and a carboy.

Yes, I am still using it with no problems. I love the way it controls temperature and also when I am not using it I can easily move it out of the way or hang it up on the wall, it is very light. I am using a Johnson Temp Controller to switch the iceprobe ON/OFF. The Iceprobe guys also sell a temperature probe/controller but I don't know much about it. So far, I have not seen any reason to add a heater because my basement is pretty steady around 70 F. Good luck to you!

Jon!!! Thanks for the test results.

I am now sold on the need for a Water Fermentation Chiller like in the link posted earlier.

A little tweaking is needed since I will not be able to replace frozen water jugs daily as he does.

An idea I have is to pull the water through a radiator mounted inside my beer fridge. A heater core from a large car would be perfect for this. Then have a fan blowing through the radiator which blows only when the pump is on.

This is a great hobby! Now, where did I leave that hole saw?

Do you happen to know if a Better Bottle has similar heat transfer properties as a glass carboy or ale pail?

Edit: Sorry wrong thread.