Mini Fridge To Cool Water for Flex Ferm Coil Idea

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May 5, 2020
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Queens, NY
I currently have 5gal of beer fermenting in my new Flex+ and couldn't be more excited. So excited in fact that I skipped an important trial for cooling during my initial tests.

I have the cooling coil package with pump sitting in a cooler of water/ice. My current setup is a 10gal cooler filled with water and ice packs to maybe 6-7gal capacity. I have been swapping out ice packs every 6-8 hrs during peak fermentation and every 12-18 hours to maintain, and removing roughly half of the warm water to replace with refrigerated water. Ferm temp is set at 66 and I've been holding pretty close but with a lot of maintenance.

I am looking for better ways to maintain fermentation temp and possibly cold crashing, and happen to have a spare mini-fridge. My idea is to fill a vessel of water inside the fridge with the greatest capacity with space available, ~3gal, run the lines from the Flex+ coil into the fridge and into the water vessel in the fridge, and keep the fridge temperature probe in the vessel of water. My hope is that I can keep the water cool enough where it doesn't freeze when not being pumped and yet can cool down enough to keep the fermenter happy and possibly bring it close to cold crashing as I can.

Does this seem feasible or a pipe dream without glycol or other setup? I've never had the opportunity to control fermentation temps since this setup.


Active Member
Apr 23, 2010
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Totally feasible. I copied others and built my own chiller. I took the cooling
coils from a mini fridge, and submerge them in a water/glycol mixture. Otherwise, the water just freezes into a block. Add a temp controller and pump and you've got a chiller to control fermentation temps.


Supporting Member
HBT Supporter
Apr 5, 2016
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I have the exact same set up. It works "ok" but I cant cold crash. Its very good at maintaining a temperature though. I can set it to 65F and it will stay that temperature throughout the fermentation process. But it cant cool the liquid down enough to rapidly drop the temp before transferring it to the keg.