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Old 12-06-2007, 04:42 AM   #1
skipdog
 
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May 2007
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Who out there uses a thermowell? I just purchased one and used with a ranco temp control and am not satisfied. I may be doing something wrong. Please let me know? I have a chest freezer(Temp controlled) and put the ranco thermocouple down the thermowell tube and set at 70 degrees with a 1 degree differential. The ambiant temp got so cold by the time the freezer shut off that the batch went down to 55 degrees and never warmed up since. I took it out of the thermowell and placed on the outside of the bucket for now. How are you guys using that piece of **** without getting such a drop in temps?

Please tell me....
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Old 12-06-2007, 05:49 AM   #2
WBC
 
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It has to do with thermal transfer and time. The larger the substance the thermowell is in, the longer it takes that substance to transfer the heat out of the substance into the refrigerated space. So I have discovered that you need to place the thermowell in a smaller volume of liquid and the transfer of heat will be faster and the cold will not dip so far below as it did before in the interior of the freezer or refrigerator. At first when the carboys are placed in the fridge the heat differential is huge and so the fridge works real hard to bring the interior down because you have the sensor in that 80 degree mass (in a thermowell) but once it gets to be equal to the set temp of the Ranco it is then off for large periods of time. I find this does not work well. I just put my Ranco sensor in the interior and let it hang in the air until the carboy is at the same temp as I set the Ranco and then place the sensor in the thermowell in a smaller container of water. This works well for me. This way you can open the door without it starting up because hot air rushes in. It takes a few minutes for the small water container to warm a bit. Some people just let the Ranco sensor hang in the air in the interior of the refrigerator or freezer and avoid the thermowell altogether and that works for them.
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Old 12-06-2007, 05:33 PM   #3
Bobby_M
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Yup, you've just seen the effect of insulating the controller probe with 5" of liquid on all sides. Ideally, the probe would sit in the beer but only say 1" from the container wall. That way it's measuring closer to the average temp of the liquid and would respond faster. The easiest method, not too far off from the best, is to securly tape the sensor to the side of the carboy and insulating it from the ambient air with some foam insulation. That way, it's measuring a bit more of the liquid temp and less of the ambient. I know that's not what you want to hear when you just dropped the dime on the well.

If you happen to use a bucket fermenter, you could very well make a new hole in the lid so that the thermowell does sit closer to the sidewall. This isn't so easy in a carboy.
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Old 12-06-2007, 07:23 PM   #4
skipdog
 
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May 2007
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Thanks for the advice. I used to put the probe on the outside of the bucket secured with duck tape. I bought the thermowell thinking it would be better but i will revert back to the old tape trick on the outside. I may try the method of modifying a new lid and drill closer to the wall.

Thanks again....
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Old 12-06-2007, 08:43 PM   #5
Bobby_M
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You can also just plug the old hole with a solid stopper but the lids are probably about the same price.
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Old 12-06-2007, 09:31 PM   #6
Beerthoven
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Quote:
Originally Posted by skipdog
Thanks for the advice. I used to put the probe on the outside of the bucket secured with duck tape. I bought the thermowell thinking it would be better but i will revert back to the old tape trick on the outside. I may try the method of modifying a new lid and drill closer to the wall.

Thanks again....
Bubble wrap seems to work well as an insulator. I tape a two or three layer square of bubble wrap to my carboy on three sides. Then I push the probe down into the pocket through the open fourth side as far as it will go.

Temp stays much more stable than when I just dangled the probe in the air.

 
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Old 01-23-2012, 04:37 PM   #7
Swilldog
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Skipdog, I'm having the same problem. I'm currently fermenting in a 15 gal firestone keg using a 24 inch thermowell on a modified keg lid, with a Johnson digital controller. I set the controller to 64 degrees and the ambient temp reached 58 degrees before the refrigerator shut off. I thought this would enable me to control temps more accurately, but the exact opposite has happened.

I'm going back to the way I originally controlled temps, I wrapped an old bungy cord around my keg and placed the probe under the cord, and this worked great. I also added another keg filled with water to add thermal mass.

 
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Old 01-23-2012, 09:52 PM   #8
phoenixs4r
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Fan + heat source = win.

 
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Old 01-25-2012, 06:07 AM   #9
BigRedOne
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This is interesting, as I have just bought one as well. I plan on using a chest freezer and one of the space heater pads that the HBS sells. I actually work for Johnson Controls and I acquired a controller that has many inputs and outputs so I can control and program it however I want. I was hoping with the thermowell that I could control the actual temp of fermentation rather than the ambient temp. I may just have to fill a carboy with water to test it out. I can gather data samples from the sensors and plot the "ambient" temp in the freezer next to the thermowell temp. Has anyone actually used one successfully?

 
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Old 01-25-2012, 03:00 PM   #10
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Quote:
Originally Posted by Swilldog View Post
Skipdog, I'm having the same problem. I'm currently fermenting in a 15 gal firestone keg using a 24 inch thermowell on a modified keg lid, with a Johnson digital controller. I set the controller to 64 degrees and the ambient temp reached 58 degrees before the refrigerator shut off. I thought this would enable me to control temps more accurately, but the exact opposite has happened.

I'm going back to the way I originally controlled temps, I wrapped an old bungy cord around my keg and placed the probe under the cord, and this worked great. I also added another keg filled with water to add thermal mass.
Try adjusting the thermostat in the refrigerator so it shuts off earlier, closer to the temp you want the beer. Remember, you are measuring the beer temp while the refrigerator is measuring the air temp.

 
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