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New fermenter, confused about temp control device, probe,and thermowell configuration

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  • New fermenter, confused about temp control device, probe,and thermowell configuration

    I am in the process of acquiring all of my fermenter/chiller parts and am confused as to how the temperTure control plugs into the fermenter via a thermowell... looking at a Johnson control temp controller. I have a tri clamp port on the jacketed fermenter. Would I have to purchase a separate probe or would the ones that come with the Johnson controller plug directly into the thermowell? Uggggg thanks

  • #2
    Originally posted by Beardown View Post
    I am in the process of acquiring all of my fermenter/chiller parts and am confused as to how the temperTure control plugs into the fermenter via a thermowell... looking at a Johnson control temp controller. I have a tri clamp port on the jacketed fermenter. Would I have to purchase a separate probe or would the ones that come with the Johnson controller plug directly into the thermowell? Uggggg thanks
    It's impossible to say without more information on what you have. But typically there is a TC thermowell that goes into your tri clamp port. Then the temperature probe goes into the thermowell. Some probes have a spring-loaded end that keeps the RTD in contact with the end of the thermowell. I think that's less common in a thermocouple sensor. There should be a dab of heat sink compound on the end of the probe but it depends on the geometry of the assembly...you may have to schmear the whole thing with thermal mastic.

    Often the whole thermowell is packaged with the RTD in it already...if that's what you got with your temperature controller, you can use it as-is, or perhaps you'll need to get a tri-clamp to thread adapter. It depends on what you have. Then you connect a signal wire between the terminal block in the thermowell, and your temperature controller. What you use for signal wire matters greatly in some cases.

    If your temperature controller is one of those cheap ones that comes with a pre-attached probe, you'll probably need a thermowell. I wouldn't put that in the fermenter directly.

    Ultimately, you want to go: beer > thermowell > thermal mastic > Temperature sensor > terminal block > Temperature controller.

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    • #3
      Ideally you would use a temperature probe that's designed for your thermowell. That would be a Tri-Clover assembly with a probe that's just a tiny bit longer than the well itself, spring-loaded so it makes good contact with the end of the well.

      However, that's would end up costing as much as the Johnson Control and you'd have to do some work to make sure its signal was compatible with the Johnson Control.

      You can certainly get away with using the Johnson Control's sensor. The important thing is to make sure it's reading the temperature of the beer, and not the surrounding air. You already can't touch the beer, but the wall of the thermowell *is* touching the beer so you have to make good contact between the thermowell and the sensor. If you just stick the sensor inside it will mostly be touching air, which means difficulty reading the beer temperature.

      I would get a long syringe and squirt a blob of thermal paste (i.e. thermal grease, heat transfer paste, etc.) into the very end of the thermowell. Then use a stick, wire, or other tool to jab the sensor down into that blob of paste. The paste conducts heat a lot better than air. Now stuff a wad of foam rubber into the thermowell opening to keep warm air out and help to hold the sensor wire in place.

      The paste won't dry out and glue the sensor in place so this isn't anything you can't change later.

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      • #4
        Thanks for the info. Right now I just have the fermenter with the tc port. How is your guys system set up? Would a pt100 probe attracted to the Johnson controller be an option?? If so how is this probe connected to the controller?since the controller comes with a prob (like the a419)? Another example - say I get a 9 inch thermowell. I would then need a 9 inch thermometer probe, correct? In this case how is the 9 inch temp probe attracted to the Johnson controller to give me a temp reading?

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        • #5
          Originally posted by Beardown View Post
          Thanks for the info. Right now I just have the fermenter with the tc port. How is your guys system set up? Would a pt100 probe attracted to the Johnson controller be an option?? If so how is this probe connected to the controller?since the controller comes with a prob (like the a419)? Another example - say I get a 9 inch thermowell. I would then need a 9 inch thermometer probe, correct? In this case how is the 9 inch temp probe attracted to the Johnson controller to give me a temp reading?
          It depends on your controller. If you have the A419, its designed for a specific probe, I think it's the A99, which is a resistive sensor on a silicon IC chip. A PT100 probe will only work with controllers that support RTDs. Usually these come already installed in a thermowell, and are used with higher end controllers (e.g. PID controllers). Neither are cheap, and probably overkill for a fermenter, which has simple on/off thermostatic control anyway.

          So if you have an A99 probe, follow Yellowbeard's advice: slide it into the thermowell with some mastic, shove some foam rubber in behind it, connect the wire to your controller, and start fermenting.

          Note, the A419 controller has several operating modes. Read the manual thoroughly to make sure you know how to set it up. If you buy a more expensive themowell, it should have a connection block in it where you attach the probe leads, and then run wires from there back to your controller. Because the peckerhead on the thermowell has a conduit fitting, you can protect it all in liquid tight flexible conduit. If you have a cheap ass homebrew style thermowell, there's no conduit body to protect your wiring, so jury-rig it up as necessary. But protect the wiring as best you can.

          Regards,
          Mike Sharp

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          • #6
            Has anyone used the a419 a99 combo? The a99 probe seems really short for the jacketed fermenter ... is there a longer probe comparable? Can't wrap my head around this one for some reason

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            • #7
              Originally posted by Beardown View Post
              Has anyone used the a419 a99 combo? The a99 probe seems really short for the jacketed fermenter ... is there a longer probe comparable? Can't wrap my head around this one for some reason
              The probe doesn't need to be the whole length of the thermowell. You just need the tip of the probe to touch the end of the thermowell (with the mastic paste). Stuff enough cord in that it reaches down to the end.

              As others have said, use a syringe (or straw attached to your mastic paste) to fill the thermowell. Use a stick of some sort to push the probe all the way in as far as you can.

              If I remember the a99's have like a 1/2" or 1" "probe end". That's plenty as the temperature is actually read near the tip. Longer thermocouples/rtds are really just for convenience. (Or if you don't use a thermowell - direct liquid measurement)

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              • #8
                Ah ok, starting to make sense. Would a 9 inch thermowell filled w paste with the a99 pushed all the way to the end be feasible to give an accurate reading ? Anyone have a thermowell recommendation for this type of setup? Thanks again for all of your help, this part is completely new to me ! Ugg

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                • #9
                  Originally posted by Beardown View Post
                  Ah ok, starting to make sense. Would a 9 inch thermowell filled w paste with the a99 pushed all the way to the end be feasible to give an accurate reading ? Anyone have a thermowell recommendation for this type of setup? Thanks again for all of your help, this part is completely new to me ! Ugg
                  Any depth thermowell will give an accurate reading, but the reading will be at the depth of the thermowell.

                  I.E. - if you use a two inch thermowell, you may receive a colder (but still accurate) reading, due to being closer to the glycol jacket.

                  I'd recommend at least 4-5" to get a good average temp reading. Longer is fine, but probably costs more. Temps during fermentation will be fairly even due to convection and yeast activity. When the beer is crashed, you will have more variance from top to bottom and more heat in the cone (from yeast activity and insulation).

                  Look at Brewers hardware for a cheaper one, or GW Kent if you like to spend money.

                  What are you called and when do/are you open? - My sister lives in Brec and I'll send her to try your beers!

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                  • #10
                    Ok great, I think I got it... we just recently picked up the system and fermenter so we are a ways off from opening. We want to have everything in line before we get into a lease etc. Small 3 bbl nano operation! What does the sis do up here? Also any recommendations on a temp controller to use? Just threw the a419 out there as an option but am hearing that it may not be the best for ferm contril? Thoughts on this? Experience with a specific temp control? Thanks

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                    • #11
                      You don't need to fill the thermowell with paste, either. Just apply a gob to the end of the probe, slide it in until it won't go any further (this will spread the paste out when it bottoms). Then shove some foam rubber in there to hold it securely in the well. The paste is just to make a good thermal connection between the probe and the wall of the thermowell. Filling the tube doesn't really help, it just increases the thermal mass of the probe. A metal-to-metal contact with a small amount of thermal paste is best.

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                      • #12
                        Cool, what is this foam rubber that u speak of that holds it in place?

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