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Author Topic: Fermentation chamber questions  (Read 1235 times)

Offline Alfredbrewer

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Fermentation chamber questions
« on: December 11, 2020, 01:51:20 pm »
I’m going to convert my 7 cu ft deep freezer into a fermentation chamber. I have a Johnson a421 wired controller. My two questions are 1) do I just plug the freezer into the controller and set the temp with it while leaving the existing freezer control alone and 2) if I’m not using a thermowell should I put the probe in a beer bottle of water for a liquid reading or could I put the probe on the side of my bucket and cover it with insulation and tape it to the side to try to get a reading from the actual fermentation? Thanks.

Offline ravenwater

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Re: Fermentation chamber questions
« Reply #1 on: December 11, 2020, 02:54:31 pm »
I don't know that it really matters where the freezer's control is set - your additional temperature controller will determine when (how much) the freezer cycles to stay cold. On my similar setup - a freezer used for fermentation chamber - I have the freezer's controller set fairly low and it does fine, but again, if it were set lower it wouldn't matter because it shuts off when my temp controller tells it to. I question how accurate your reading would be with the probe taped to the side of your fermenter (bucket, etc). That will not reliably give you the actual temperature within your fermenting wort, which can run higher due to exothermic reaction in the yeast activity. A thermowell is more ideal for this, but without one you would do just as well to have your probe
in a decent sized thermal mass that changes temperature more slowly than the ambient air in the freezer. A beer bottle would approach this but before I got a thermowell I used a gallon jug filled with water to hang the probe in - more mass, slower temp change = the freezer holding more reliably within a set temperature versus rapid cycling on and off if the air inside the freezer warms. I feel this is no worse and likely better than a probe taped to the fermenter, even if insulated.
« Last Edit: December 11, 2020, 02:58:41 pm by ravenwater »
Shawn Crawford  -  Rio Rancho, NM.  
 BJCP, Worthogs Homebrew Club of New Mexico

Life is good. Beer makes it gooder.

Offline Alfredbrewer

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Re: Fermentation chamber questions
« Reply #2 on: December 11, 2020, 04:43:06 pm »
Thanks for the help. I considered putting the probe in a growler of water and going 10 degrees or so below target during the initial activity and then gradually bumping it up, but it sounds like I should just get lids for thermowells for a bucket and a bigmouth bubbler. I have 3 of each, but none are setup for a thermowell. If that’s the best way for accurate control, then I’ll go that route. I appreciate the info.

Offline ravenwater

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Re: Fermentation chamber questions
« Reply #3 on: December 11, 2020, 06:26:10 pm »
Yes, if you’re willing to spring for lids an a thermowell or two I think you’ll be happy with the result. What I like about that setup is that as the beer warms due to fermentation activity the chamber cools according to the setpoint on my controller to hold at my ideal fermentation temperature. Good luck & happy brewing. Cheers!
Shawn Crawford  -  Rio Rancho, NM.  
 BJCP, Worthogs Homebrew Club of New Mexico

Life is good. Beer makes it gooder.

Offline wst

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Re: Fermentation chamber questions
« Reply #4 on: January 14, 2021, 09:08:38 pm »
I have a chest freezer and use an inkbird controller.

I used a thermowell but the problem I had is when the freezer went on to cool the wort it would take a long time to bring the 5 or 6 gallons down a degree and then it would cool it too much because the freezer itself would be pretty darn cold by then.

I use glass carboys.   I have the thermopen that has a waterproof lead and probe that I use for brewing and for the freezer.  I took some flexible foam and plastic bubble wrap, and cut out the foam so the probe will lay flat against the carboy and be insulated from the ambient temperature after I metal duct tape and seal it to side of the carboy.

I hang the inkbird probe from the underside of the lid to read the ambient temp in the freezer.  This has worked well.  The probe on the glass of the carboy reads, I think, pretty accurate wort temp.   I can keep the ambient temp at levels that control the wort temp +/- a degree and if it gets out of whack then can raise or lower ambient and get it a back to in several hours without over/under shooting.  (I also have a little personal heater plugged into the inkbird).