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Thermowell

Got a couple of toys for Christmas ( a thermowell and a digital thermostat controller ). Started a batch on Thursday and put the thermowell into the carboy and slid the probe into the thermowell. It seems to be right on target of 55 degrees, but when checking it tonight found freezer running and the water in the airlock almost frozen. Now realizing that the ambient temp outside of the carboy is not the same as the wort inside. The thermometer I have hanging in the freezer said 25 degrees. I pulled out the probe and the freezer went off right away. Has anyone else experienced this and what can you do to fix it? Am afraid of waking up to a slushy in the am!! :cheers:

I just got a thermowell and plan on putting it to use this weekend. In the past I have taped my probes to the carboy. What controller are you using? What was your starting beer temp? Also what was your +/- setting?

My starting temp was 55 degrees. Cooled the wort down to 52 and let it free rise to 55 degrees. It has been ok since Thursday night and the temp on my thermometer hanging in the freezer was showing 54 degrees (very close). Tonight as mentioned, the freezer was running and the airlock was almost frozen, so I guess the freezer will run until the probe senses the correct temp inside the carboy. It could take a while for the wort to cool to proper temp since it is in the middle of the carboy and the outside air is cooling the liquid from the outside in. Thought this would be a more precise temp having the probe inside, but looks like trouble as the ambient temp in your freezer might get really low. Mine was down to 25 degrees and I’m sure the airlock would have froze if had not checked it. It has a +/- of 1 degree and is a Unistat-G

Something seems very wrong to me, perhaps with your unit. You are correct, if it is working correctly the freezer should run until you come within a +/- 1 of your temp; but even if you have 6 gallons of wort, I can’t imagine a 30 degree swing in ambient would not trigger a +/- 1 difference setting to shut the freezer off. My freezer temps don’t dip that low.
Do you have a fermometer on the carboy by any chance or can you take a reading with a standard thermometer?
If everything is proven to be working fine, and I’m very skeptical of that, you may need to switch to vodka in that airlock!

I have a fermometer on the carboy and it was in the 54-58 range which would support the reason the thermostat kicked on the freezer. The air temp was 25 degrees and airlock almost frozen when I noticed. It might have been ready to shut down soon when I noticed it. Might be a good idea to use vodka in the airlock. One thing not to do would be to put the probe in the thermowell if you are not close to your fermenting temp. If I would have done that the airlock would have frozen + possibly the wort on the outside reaches of the carboy may have frozen. :cheers:

It kind of sounds like the controller mode switch was set to heat, rather than cool.

How sure are you the accuracy of the hanging thermometer inside the freezer? It’s possible you have a very efficient freezer and can cool off the air much quicker than it takes to lower the temperature of 5 gallons of beer 1 degree I suppose.

This is a possibility! Again I’m not sure of your controller specifics, but my Johnson controllers have both heat and cool options, along with cut in and cut out settings. If it was on heat mode, it would run that freezer until it turned your beer to ice.

This is a possibility! Again I’m not sure of your controller specifics, but my Johnson controllers have both heat and cool options, along with cut in and cut out settings. If it was on heat mode, it would run that freezer until it turned your beer to ice.[/quote]

If that were true, the controller wouldn’t have shut off when put in the colder ambient temps.

This is a possibility! Again I’m not sure of your controller specifics, but my Johnson controllers have both heat and cool options, along with cut in and cut out settings. If it was on heat mode, it would run that freezer until it turned your beer to ice.[/quote]

If that were true, the controller wouldn’t have shut off when put in the colder ambient temps.[/quote]
Good point.

The controller has a heat and cool and it is set to the cool. Think it may be due to my freezer (an upright) rapidly cooling as it has a fan to blow the air which circulates it better than a chest freezer
causing things to chill down quickly. Kept an eye on it last night and decided to leave to probe inside the well. When I checked today it was fine and 55 degrees. As stated before-- advising anyone with a heavy duty freezer not to put the probe in if the wort is 10 + degrees above your target as freezing could occur. :cheers:

[quote=“lagerhead”]The controller has a heat and cool and it is set to the cool. Think it may be due to my freezer (an upright) rapidly cooling as it has a fan to blow the air which circulates it better than a chest freezer
causing things to chill down quickly. Kept an eye on it last night and decided to leave to probe inside the well. When I checked today it was fine and 55 degrees. As stated before-- advising anyone with a heavy duty freezer not to put the probe in if the wort is 10 + degrees above your target as freezing could occur. :cheers: [/quote]

If all it was freezing was your sanitizer water I don’t see it as much of an issue. Like other stated, using vodka would eliminate that. It’s not freezing your wort because that is a much larger thermal mass than what’s in your airlock. You said both the thermowell temp and the fermometer temp were in the mid 50’s. You may have some discrepancy in temperature between wort closer to the edge of the carboy and in the center where the thermowell is but I can’t see that being more than a degree or two.

The only way I can see it being an issue is if you had something like a 1 gallon and a 5 gallon carboy and put the thermowell in the 5 gallon.

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