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Fermenting In A Chest Freezer, Issues With Temperature Swing.

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pat_00

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Hello internet.

I have just finished my first brew in my new fermenting chest. I'm having some problems with temperature swings.

Previously I was using a spare fridge for this, and the temp stayed much more consistent. With my new chest freezer setup, I am seeing variation of +/- 2 degrees. I am using an STC1000 controller, no heating attached. I would of assumed that my temps would be more stable with a chest freezer.

Any Ideas of how to solve this?
 

Nick JD

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Stick the probe to the fermenter with an old stubbie-cooler over it as insulation.
 

QldKev

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Stick the probe to the fermenter with an old stubbie-cooler over it as insulation.
+1

You don't care what the air temp is, it the wort temp that matters.

QldKev
 

tricache

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I have some guys put a stubbie (or some a small body of water) and put the probe in that....that way you are actually measuring an actual liquid temp not the air temp
 

QldKev

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I have some guys put a stubbie (or some a small body of water) and put the probe in that....that way you are actually measuring an actual liquid temp not the air temp

It's the temperature of the fermenting wort that matters.

Firstly cooling a small stubby of water will happen faster than a large container of wort. Hence the stubbie will be at temp fairly quickly, but the wort will be warmer for longer, not good.

Secondly the stubbie may start at a different temp. Ie. the stubbie is already at fermenting temp from sitting in the fermenting chamber, and you add a new fermentor of warmer beer. Mmm, stubbie is correct temp, wort stays too warm.

Thirdly wort fermenting is exothermic (produces heat), so in the same chamber the stubbie will most likely be cooler than the wort. This is mainly in the earlier stages of fermenting, but this is when the flavours are produced.


QldKev
 

tricache

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It's the temperature of the fermenting wort that matters.

Firstly cooling a small stubby of water will happen faster than a large container of wort. Hence the stubbie will be at temp fairly quickly, but the wort will be warmer for longer, not good.

Secondly the stubbie may start at a different temp. Ie. the stubbie is already at fermenting temp from sitting in the fermenting chamber, and you add a new fermentor of warmer beer. Mmm, stubbie is correct temp, wort stays too warm.

Thirdly wort fermenting is exothermic (produces heat), so in the same chamber the stubbie will most likely be cooler than the wort. This is mainly in the earlier stages of fermenting, but this is when the flavours are produced.


QldKev
There you go, I learnt something new today...good to know :icon_cheers:
 

pat_00

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I forgot to mention, the probe is wrapped in a layer of bubblewrap and gaffa taped to the side of my FV.
 

glenwal

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The freezer will have a greater cooling capacity than the fridge, so the air temp will get alot colder in the chesty whilst trying to get the wort temp down, and thus will cool alot more after the compressor switches off, resulting in the overshoot.
 

Nick JD

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Sounds like your probe is still registering the air temp in the freezer and not the fermenter temp. No way the fermenter is swinging plus and minus 2C with the compressor.

Perhaps try the bubble wrap only on the outside - with the probe physically touching the plastic. Also - 5mm neoprene is probably better than bubble wrap.
 

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