|Cooler with ice water (left) and cooling jacket|
with fermenter inside (right). Temperature
controller and temperature monitors visible.
One aspect I've not controlled well so far is fermentation temperature. In part, this has been because I didn't think I needed to. I brew primarily Belgian beer styles, and most of the Belgian abbey brewers let the yeast ferment at whatever temperature it wants to. They don't try to cool it, because they claim this can make the yeast stall out. They don't heat it unless it drops below the yeast's tolerance range.
That has been changing lately. Earlier this year, I added a dual-stage temperature controller and a heat wrap. This helped some of my beers attenuate a little better and kept them from suffering a slowdown in fermentation as the temperatures in my basement dropped lower. What I couldn't do, though was control the upper end of the fermentation temperature.
I questioned whether I really needed to have a fermentation cooling option. An inexpensive temperature monitor watched one of my Belgian beers ferment, recording the wort's temperature every minute for two weeks. At no time did the wort exceed the yeast's tolerance range. I concluded from this that the combination of a low basement temperature and the thermal conductivity of a stainless fermenter might have been enough cooling. It certainly was for the batch I monitored.
|Cool Zone Jacket visible around bottom of fermenter,|
and blue water in/out lines connecting to cooler
I purchased a large zippered insulated cooling bag (the large black one pictured above and to the right) and dropped two frozen one-gallon jugs of water inside. This got the fermenter temperature down into the 55-60F range and kept it there as long as I changed the ice daily. I couldn't get it below 55F until I added more ice.
There had to be a better way. That's when a web search turned up Cool Zone Fermentation Control's Cool Zone Cooling Jacket. This product is a plastic and Velcro wrapper which goes around your fermenter. Ice water is pumped into the jacket through a convoluted channel and comes out the other side. As water flows through the jacket, the water chills the fermenter. Cool Zone claims to have gotten fermenters down to as low as 36F with this technology.
I purchased the cooling jacket ($69.98), 370GPH pump ($27.95), and their starter kit of tubing ($17.95). With shipping, this cost about $133. Since I already had a temperature controller I was happy with and a cooler I could use, I didn't need to buy those. I also didn't need to buy their insulated enclosure since I had the zippered model above. (Even if I didn't have that, I wouldn't have purchased Cool Zone's. It's too small for any of my fermenters.)
It took me about ten minutes to read the setup instructions, hook up the lines, fill the cooler with water, drop in the ice jugs, and set the controller.
Several minutes later, the temperature inside the fermenter had dropped from 55F to 48F. As soon as it did, the controller cut off the pump. The fermenter remained at (or at least very near) the 48F temperature for over 24 hours. At that point, I swapped out the ice jugs in the cooler, and put the mostly-thawed jugs into the freezer for later use. With daily changes of the ice jugs, I should be able to keep the fermenter at 48F as long as needed.
Since it's something new, I'm using my temperature monitors to determine how the temperature in the fermenter and ice water vary over time. This will help me determine how quickly the product can chill a fermenter and how long I might expect the ice water to remain cold enough to keep the fermenter under control.
To take this system to the next level, I'm planning to purchase a small dorm-room refrigerator. My plan would be to cut two holes into the top of it and place a container of water inside. Then, I'd use the refrigerator to keep the water cold instead of the ice jugs. This would eliminate the need to change out ice every day or two... and would make me feel comfortable about attempting a lager style beer that might need to be kept in the 32F to 52F range for weeks at a time. With ice water, I'd be concerned that I might miss a day replacing the ice and let the beer get too warm. The constant temperature inside the dorm fridge would solve that issue.
Overall, I think the Cool Zone Cooling Jacket is a good product. I'm a little concerned that the plastic used for the section through which the water pumps is thin and could be easily damaged but haven't experienced any issues with that yet. I'm planning to add a second Cool Zone kit for another fermenter, when I'm satisfied that this is working as intended. (And so far it is.)
|Jugs still have some ice in them after 30 hours. Pump in bottom right corner.|
|Ice water temperature (34.7F) after 30 hours of use|
|Fermenter temperature after 30 hours,|