Author Topic: Ambient vs. Fermentation Temps  (Read 1481 times)

Offline cheba420

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Ambient vs. Fermentation Temps
« on: January 08, 2012, 11:30:12 AM »
I ferment in a refrigerator with a johnson control. I've read several times that fermentation increases the temperature in the carboy by as much as 5-10*. But that temperature decreases as fermentation goes on to completion. So, I know the answer to my question is to have a thermowell so I can measure the temperature of the fermenting beer. But lets say thats not an option at the moment. what should I be doing? It occurs to me that if I want to be fermenting at 68* and I set my controller to that point, I may actually be fermenting at 73-78*. Should I be adjusting the controller down to 60 or so to compensate for the fermentation temps?

Now, as the fermentation winds down, the temp of the beer will also cool down...correct? How does one measure this? Is there a rule of thumb? Should I be adjusting my temp in the refrigerator back up by the day or by gravity readings? 1 degree at a time? I make good beer but this question has always been on my mind and thought I'd throw it out here for you guys to comment on.
Matt
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Offline euge

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Re: Ambient vs. Fermentation Temps
« Reply #1 on: January 08, 2012, 11:42:45 AM »
My experience is that the interior temp of the fermenter is the same as the ambient temp of the fridge/freezer even at the height of the attenuative phase.

Leave the temp where you set it at unless you are adjusting temp according to a plan- for example raising the temp of a Golden Strong a few degrees over the course of the primary fermentation.
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Offline brushvalleybrewer

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Re: Ambient vs. Fermentation Temps
« Reply #2 on: January 08, 2012, 11:52:02 AM »
I have a thermowell, but I understand that many people tape their probe to the outside of the carboy and then cover it with some type of insulation, like styrofoam or bubble wrap, so it is mostly measuring the beer temperature. I also understand that people have found the temperature there to be within about a degree of what a probe in a thermowell reports.
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Offline Malticulous

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Re: Ambient vs. Fermentation Temps
« Reply #3 on: January 08, 2012, 05:34:16 PM »
I've seen 10F difference on a big beer. Most are just a few degrees. And yest it does go down as fermentation slows. I like to turn up the temp as it does, I usually just move the fermenter to room temp..

Offline tschmidlin

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Re: Ambient vs. Fermentation Temps
« Reply #4 on: January 09, 2012, 05:01:40 PM »
The thing to remember if you are fermenting cool is that it will slow the fermentation so it will also reduce the temp rise.  A warmer fermentation temp speed the process, so the temp goes even higher.  You need to manage it, and you'll get different results from different yeasts.

Set it a couple of degrees cooler then your desired fermentation temp and put the carboy in so that you can check the temp, whether that is from a thermowell or just a fermometer stuck on the side.  Adjust the temp up or down as needed to keep the beer where you want it.
Tom Schmidlin

Offline rjharper

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Re: Ambient vs. Fermentation Temps
« Reply #5 on: January 09, 2012, 06:46:20 PM »
I keep my carboys in a water bath, and keep it recirculating. I reckon the temperature of the beer has to be pretty much the same as the water bath since i keep the boundary layer on the outside of the glass disturbed.  This time of year I drop an aquarium heater into the water and control temps that way.

Offline tom

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Re: Ambient vs. Fermentation Temps
« Reply #6 on: January 09, 2012, 09:28:36 PM »
Which Johnson controller do you have - digital or analog?

What kind of fermenter do you use?
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Offline a10t2

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Re: Ambient vs. Fermentation Temps
« Reply #7 on: January 12, 2012, 11:47:09 PM »
Set it a couple of degrees cooler then your desired fermentation temp

+1. Also, get a $3 LCD thermometer for each of your fermenters so that you can monitor the actual beer temperatures. http://www.northernbrewer.com/shop/brewing/brewing-equipment/testing-measuring/thermometers/fermometer.html
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Offline stlaleman

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Re: Ambient vs. Fermentation Temps
« Reply #8 on: January 13, 2012, 02:53:53 AM »
Had my glycol pump die on one batch of ale. This was a ten gallon batch, but the temp went up 88 in a 72 degree room, was fermenting at 65, and it was a Scottish 70l beer. The temp does shoot up quite a bit. I strongly suggest a thermowell (sp?) for beers that you are interested in temp controllling.

Offline davidgzach

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Re: Ambient vs. Fermentation Temps
« Reply #9 on: January 14, 2012, 07:21:58 AM »
+1 on the thermowell, but mainly for lagers for me.
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Offline cheba420

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Re: Ambient vs. Fermentation Temps
« Reply #10 on: January 14, 2012, 08:16:07 AM »
Which Johnson controller do you have - digital or analog?

What kind of fermenter do you use?
Its an analog controller so I realize it doesnt have the precision of the digital. I have a few different fermentation vessels. If I only have one 5g batch going I ferment in my7.5g stainless conical. Other 5g batches go into glass carboys. If I max out there I have a couple of buckets handy. I ferment my 10g batches in a 15.5g sankey keg conversion.
Matt
Mesa, AZ.
#197645

On Tap: Vanilla Porter, Belgian Blonde, Saison, Black IPA, Punkin Porter
Primary: Pale 31 Clone, Raspberry Cider
Secondary: Vanilla Porter
Conditioning: Brett IPA
Bottles:Mosaic Wheat
On Deck: Flanders Red, Berliner weisse, Punkin Saison, Saison Brett