I wanted to document my experience building a fermentation temperature control system based on Gotta-Brew's Cool Zone cooling jacket. I finally finished it up last night it works, so it's time to post!
Plan
The system is based on a cooling jacket around my carboy. Gotta-Brew's Cool Zone system includes a ready-made cooling jacket and insulated cover that fits my 6.5 gallon carboy nicely. Next to the carboy is a round Igloo cooler filled with ice water. The cooler houses a small submersible pump. The pump is plugged into the STC-1000 temperature controller. Inside the cooling jacket, taped to the carboy, is a heatwrap, which also is plugged into the temp controller. When cooling, the pump will circulate cold water through the carboy jacket. When heating, the heatwrap will activate and surround the carboy with heat. Temperature is monitored by the STC-1000 sensor inside a stainless steel thermowell placed inside the carboy. It measures the temperature of the fermenting beer itself rather than the ambient temperature.
One initial decision was whether to use a standard cooler for the cooling water or use my kegerator. Using the kegerator would require an additional hole through the side and a long-ish run of tubing that would need to be insulated. A separate cooler, in contrast, would require frequently replenishing the ice inside to keep the water cold. The separate cooler likely would be more compact, because it could be stored on the shelf next to the fermenter and the tubing would only need to span 1 to 2 feet instead of nearly 10 feet.
With only one batch fermenting at a time, I decided to start with the cooler and move to using the refrigerator if there becomes a need to ferment multiple batches at a time.
Components
- Cool Zone cooling jacket (purchased)
- Carboy thermowell (DIY) (completed)
- STC-1000 controller (DIY) (completed)
- Submersible pond pump (Amazon) (purchased)
- 1/2 ID tubing (no need to be food safe) (purchased)
- tubing quick connects (included with Cool Zone jacket)
- 5 gallon Igloo cooler (purchased)
Progress
I received the CoolZone jacket and 25 watt heater as a birthday gift from my lovely SWMBO. I also purchased a small submersible pond pump, some 1/2 ID tubing, and the parts to build a DIY temperature controller based on the STC-1000 unit.
I built the thermowell using a plain stainless steel thermowell from Brewhardware. I coated the STC-1000 sensor with thermal paste and slid it to the bottom of the thermowell. I then covered the top of the thermowell with shrinkwrap to make a splashproof seal around sensor wire.
I completed the STC-1000 controller last night and was gratified to have it work the first time I plugged it in. I guess Ive learned something from my EE dad! After reading the instructions, I programmed it to maintain 19.5 C (~ 67 F). I drilled a second hole in my spare stopper and sanitized it and the thermowell. When placed in my fermenting beer, it read 22 C (~ 70 F). After a 3 minute delay (the default setting on the STC-1000), the pump came on and began pumping cold water through the cooling jacket. Because the pump is inside the cooler with the lid shut, I could barely hear it when it came on. But you could see the cold water moving through the hoses.
After a few minutes, the temp dropped 0.1 C, and a few minutes later, 0.2 C. I would expect the temperature changes to be rather slow, given the thermal mass of 5 gallons of fermenting beer. I checked it this morning and it was a steady 19.6 C, within the 0.5 hysteresis setting of my 19.5 target temperature. All of the ice in the cooler was melted, so I added a frozen 1/2 gallon milk carton. It will take some time to determine how often ice needs to be replenished in the cooler. It will also require some experimentation to see whether the cooling jacket can bring the carboy temp down to cold crashing or lagering ranges.
Future Improvements
Future improvements include flashing the firmware on the STC-1000 to allow for setting and reading temps in F, and to program steps at different set points, set forth in this great thread. At $20 for a STC-1000, the risk is minimal.
Another improvement would be to move the pump and water bucket into my kegerator. There are three major hurdles to overcome: (1) distance between carboy and kegerator (placing it adjacent is not possible, because my wine refrigerator is next the kegerator); (2) drilling another hole in the refrigerator; and (3) finding room in the refrigerator, which is used for storing food as well as being a kegerator.
This was a fun project, and it was good to tackle the "cold side" of my process after building my electric BIAB kit (see build thread here).
Plan
The system is based on a cooling jacket around my carboy. Gotta-Brew's Cool Zone system includes a ready-made cooling jacket and insulated cover that fits my 6.5 gallon carboy nicely. Next to the carboy is a round Igloo cooler filled with ice water. The cooler houses a small submersible pump. The pump is plugged into the STC-1000 temperature controller. Inside the cooling jacket, taped to the carboy, is a heatwrap, which also is plugged into the temp controller. When cooling, the pump will circulate cold water through the carboy jacket. When heating, the heatwrap will activate and surround the carboy with heat. Temperature is monitored by the STC-1000 sensor inside a stainless steel thermowell placed inside the carboy. It measures the temperature of the fermenting beer itself rather than the ambient temperature.
One initial decision was whether to use a standard cooler for the cooling water or use my kegerator. Using the kegerator would require an additional hole through the side and a long-ish run of tubing that would need to be insulated. A separate cooler, in contrast, would require frequently replenishing the ice inside to keep the water cold. The separate cooler likely would be more compact, because it could be stored on the shelf next to the fermenter and the tubing would only need to span 1 to 2 feet instead of nearly 10 feet.
With only one batch fermenting at a time, I decided to start with the cooler and move to using the refrigerator if there becomes a need to ferment multiple batches at a time.
Components
- Cool Zone cooling jacket (purchased)
- Carboy thermowell (DIY) (completed)
- STC-1000 controller (DIY) (completed)
- Submersible pond pump (Amazon) (purchased)
- 1/2 ID tubing (no need to be food safe) (purchased)
- tubing quick connects (included with Cool Zone jacket)
- 5 gallon Igloo cooler (purchased)
Progress
I received the CoolZone jacket and 25 watt heater as a birthday gift from my lovely SWMBO. I also purchased a small submersible pond pump, some 1/2 ID tubing, and the parts to build a DIY temperature controller based on the STC-1000 unit.
I built the thermowell using a plain stainless steel thermowell from Brewhardware. I coated the STC-1000 sensor with thermal paste and slid it to the bottom of the thermowell. I then covered the top of the thermowell with shrinkwrap to make a splashproof seal around sensor wire.
I completed the STC-1000 controller last night and was gratified to have it work the first time I plugged it in. I guess Ive learned something from my EE dad! After reading the instructions, I programmed it to maintain 19.5 C (~ 67 F). I drilled a second hole in my spare stopper and sanitized it and the thermowell. When placed in my fermenting beer, it read 22 C (~ 70 F). After a 3 minute delay (the default setting on the STC-1000), the pump came on and began pumping cold water through the cooling jacket. Because the pump is inside the cooler with the lid shut, I could barely hear it when it came on. But you could see the cold water moving through the hoses.
After a few minutes, the temp dropped 0.1 C, and a few minutes later, 0.2 C. I would expect the temperature changes to be rather slow, given the thermal mass of 5 gallons of fermenting beer. I checked it this morning and it was a steady 19.6 C, within the 0.5 hysteresis setting of my 19.5 target temperature. All of the ice in the cooler was melted, so I added a frozen 1/2 gallon milk carton. It will take some time to determine how often ice needs to be replenished in the cooler. It will also require some experimentation to see whether the cooling jacket can bring the carboy temp down to cold crashing or lagering ranges.
Future Improvements
Future improvements include flashing the firmware on the STC-1000 to allow for setting and reading temps in F, and to program steps at different set points, set forth in this great thread. At $20 for a STC-1000, the risk is minimal.
Another improvement would be to move the pump and water bucket into my kegerator. There are three major hurdles to overcome: (1) distance between carboy and kegerator (placing it adjacent is not possible, because my wine refrigerator is next the kegerator); (2) drilling another hole in the refrigerator; and (3) finding room in the refrigerator, which is used for storing food as well as being a kegerator.
This was a fun project, and it was good to tackle the "cold side" of my process after building my electric BIAB kit (see build thread here).
