View Full Version : Best practice for multiple temp probes per tank

07-30-2010, 07:40 AM
I am installing new 60bbl tanks. Each has three cooling jackets and also three thermowells for temperature probes. With stratification I can see each temp probe reading something a bit different. Should I just put a probe in the middle of the tank? Should I somehow put in three probes and then take an average? Should I have a solenoid and probe per jacket to control these independently? The latter sounds expensive. What do other people do?


James Murray
07-30-2010, 08:54 AM
We have several 60 BBL, 80 BBL, 100 BBL, and 200 BBL tanks that came with multiple thermowells. We opted to put a single probe in the middle of the tank since our glycol controls are linked to the probes. I know that Stone Brewing has 3 probes per tank on their 450 BBL tanks. You might want to give those boys a call. I haven't experienced any stratification in our tanks, but we are also filling them in a 24 hour period. Good Luck.

James Murray
Lead Brewer
Ballast Point Brewing & Spirits
San Diego, CA

Ted Briggs
07-30-2010, 10:22 AM
Independent jacket control is ideal. This would need 3 probes and separate lines and solenoids for each jacket. You should be able to run them off of one controller per tank though, with 3 outputs and inputs.
And yes it will cost a little more, but its worth the added performance and flexibility, ie: partial batches or cone cropping yeast, and improved performance in cooling.
Id ask Pro-Refrig. for their opinion...

dick murton
08-06-2010, 10:50 AM
During fermentation, a single probe, normally just above the cone will suffice due to the recirculation currents. However, if you unitank, and cool in the tank without recirculation or tank to tank transfer, then a probe at the top is required due to the density of water / beer being greatest at about 4 C. Without a switch to a high level probe under these conditions it is easy to form ice layers on the top.

If you have more than one temperature probe, then I suggest you use the one just above the cone for control during fermentation and cooling down to about 6 C, and the top one for temperatures < 6 C, but use the others as cross checks only. Using an average is a recipe for disaster during cooling post fermentation (ice formation at the top again)


08-06-2010, 11:47 AM
If the probes are thermocouples then wiring them in parallel should produce and average.

I agree that individual control is the way to go if you can afford it.


08-06-2010, 10:39 PM
Beermkr, does wiring thermocouples in parallel really work? I've never tried it. It may work with thermocouples (which actually generate a tiny current from dissimilar metals), but won't with RTDs or thermistors (which are resistance based). Usually, resistance based sensors are multiplied by an array of equal parallel and series sensors. For example, two sensors in series coupled in parallel to another two sensors in series. Two sensors in series will double the resistance, but then adding another series set in parallel halves the doubled resistance. Arrays of three x three and bigger work, too. Of course all sensors must be the same style. This array style of averaging is used in large commercial coolers.

08-07-2010, 01:59 PM
Everything I have seen/heard/read says it works for a THERMOCOUPLE. I agree it will not work for anything else for the exact reasons you say. Resistive sensors wont parallel as the resistance will not be an average but actually roughly half of the individual resistances. I cant figure out how to adequately type the formula :)

Here is reference for thermocouples in general and all that can be done with them.



08-07-2010, 08:35 PM
I have a question on the wire used, I am running two thermocouples into my control box. There are other electrical wires in the box controlling pumps and solenoids. I will be running the solenoid wire in separate conduit but they will have to be exposed in the control box unless I wrap them with some kind of wire wrap. I can set the controls for the solenoids to anticipate a difference in temperatures if I find the solenoids are reading off from actual water temp's. I am also running a very good "T Type" wire with thermal insulation to cut down on heat and electrical interference, until it runs into the box of course.

Has anyone had a problem with off temperatures due to the electrical interference in the control box? Has anyone wrapped the wires in the box and found them to be more accurate?