Temperature Control Module for Beer Fermentor

The cooler/fermentation chamber is on the left. The two white containers are 8 gallon Speigel fermentation containers. I should be able to fit quite a few of those in the cooler when I get this little project accomplished. Beer is on me!

Your diagram is close to correct. The second output is on terminals 11-12, not 5-6. To match the manufacturer's instructions you would connect the heater to OUT1 and the cooler to OUT2, leaving the "oUd" parameter set to "heat". Since cooling is your primary function, you may want to switch this around. You could swap outputs and set that parameter to "cool" so the heater will be operated on OUT2.

Make absolutely sure to set the "control" parameter for your cooling output (the "Ctl" or "C_t" parameter depending on if you connected it to OUT1 or OUT2) to a very long time period. Even the maximum value of 150 seconds is not really as long as you'd like. You MUST do this before applying power to the compressor, or you will burn it out very fast from short-cycling. Compressors do not like being turned on and off rapidly.

Some general tips on using these controllers:

- Adjust the offset parameter ("PUF", called the "modification value" by the manufacturer) to calibrate your unit to your temperature sensor before you set up anything else. Use a glass packed full of ice then partially filled with water and allowed to sit for 10min as your 32F reference for calibration. Consider using an RTD instead of a thermocouple. They are more accurate and don't require special wire.

- Run the auto-tune routine under actual conditions of use, or the controller will not tune well and you'll have all kinds of problems later. To tune, fill your fermenter with an average load of fermentation containers full of water. The amount of water in there will make a big difference in the tuning. It will take a long time to tune - many hours at least. I had one of these controlling a mini-fridge with 5gal of water in it and it took about 3 days to tune. Verify that the tune worked by refilling all the carboys with warm water, then repeat with chilled water to test heating. Check to make sure the controller does not overshoot the setpoint unacceptably, which could kill your yeast.

- If your heating/cooling devices are capable of damaging your process if the controller malfunctions, use a separate thermostat as a safety device to make sure that doesn't happen. These controllers can fail with the outputs stuck on.

twisted-brew said:

Would I be better off bypassing the analog thermostat using something like an STC 1000 to control the temperature of the cooler instead of using the TA4 to switch the entire cooler on and off? The True GDM 49 Temperature Control Unit 800283 I think is an 8 amp unit.

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I assumed there was no thermostat on the cooler or that you had already defeated it. Setting the internal thermostat to a little above freezing would be a good safety backup to prevent your fermentation containers from freezing if the controller fails.

Should you use a basic non-PID controller instead of the TA4? Yes, probably so. I thought of that earlier but didn't say anything because you are so far along on this. However, PID is total overkill and really doesn't play well with a compressor. Like the manual says, it doesn't want to be turned back on until it's been off for 5min. The TA4 will be flipping it off and on every 150 seconds! That's not much time for the system pressure to equalize, and you may find that the compressor won't restart sometimes. I had that problem on a mini-fridge and on a chest freezer that are controlled by these PID units. I switched to a programmable thermostat on the freezer and it holds +/- 2 degrees just fine now and doesn't lock the compressor. On the mini-fridge I absolutely required PID because I had to hold within less than a degree to keep salt water partially frozen. As long as the ambient temperature is less than about 80F it's fine, but if it's hotter the compressor locks from the short-cycling and it stops working.

A basic programmable thermostat will do just fine in your application and fixes this. Since you have so much water in this thing, you should be able to hold the liquid temperature at +/- a degree or so with a simple electronic thermostat like the STC1000. Put your temp probe in the air, not the liquid - unlike with a PID controller, you need the thermostat to sense changes quickly so you don't overshoot the setpoint too much. You'll set the controller deadband to several degrees (maybe 3-6), and rely on the thermal mass of the liquid to smooth out that variation so the beer's temperature only varies by a degree or two. This is a simpler and more reliable solution.

My dilemma is, if possible, I don't want the cooler running constantly. Keeping temperatures between 50* and 70* I may not have a choice considering the cooler is in the garage. It may need to run every few minutes or so. The garage ambient temp is between 75*-90* depending on how much the door is opened. I definitely don't want to burn out the compressor. From the manual: NOTE
If the cooler is disconnected or shut off, wait five minutes before starting again.

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The duty cycle of the compressor (percentage of the time it's on) depends only on the difference in temperature from inside to outside the cooler. The method of control has no influence on this. If it's 80deg in the garage and you keep the cooler at 60deg the compressor will run for the same percentage of time with a mechanical thermostat, digital thermostat, or PID controller. The only difference is in how frequently it will cycle and how tightly the temperature will be controlled. The tighter the temp control the more frequently it must cycle. That's why the internal mechanical thermostat will give you the longest cycle times and worst temp stability, the STC1000 intermediate (adjustable by changing the deadband), and the PID controller requires the shortest cycles but gives the tightest regulation.

If I went with an AGPtek Stainless Steel PT100 RTD, where do each of the three connectors go? There are two blue and a red.

I think might be in a bit over my head, but I'm savvy and a quick learn. :vs_worry:

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The TA4 wiring diagram shows the two parallel leads (both blue wires) on terminals 7 and 10, and the other lead (red) on terminals 8 and 9. As I recall, 8 and 9 must be jumpered. You'll get it all figured out!

I have an in and out on the knob control of the thermostat, both are red wires. I assume the "in" is live and so is the "out" once the thermostat switches on? Out to compressor basically. If that is the case I connect the red "out" to Pin 7 of the ITC-1000, Pin 8 is goes to the red "in" wire.

Victory!!!

Thanks again mpoulton.