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Old 11-11-2009, 04:31 AM   #1
Nov 2008
Posts: 237
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I haven't gotten too sophisicated in my brewing techniques just yet, but have been thinking about controlling my process a bit more. Fermentation temperatures being one area I'd like to have more control over. Up until now, I've just used the Fermometer adhesive tapes you stick to the side of the carboy to indicate temperatures. Not really sure how precise and accurate these are, but they've helped me produce some damn fine beer thus far. Anywho, I've heard that yeast respiration actually produces it's own heat. Adding an additional 5-10 degrees...? I'm assuming the added amount varies depending on whether it is a really high gravity liquid vs. low gravity or a very active, strong fermentation vs. slow, lethargic fermentation, etc.

So a few questions I've been pondering: do the Fermometer tapes reflect the overall temperature of the liquid (ambient temp + additional degrees added due to yeast respiration)? If the Fermometer tapes (or whatever other external thermometer you might be using) only reflects ambient temperature, then I should not be adjusting temperature control based on what the tape is reading as the internal temperature of the liquid will be higher, correct? Also, I'm just curious if anyone has ever used a really accurate thermometer to measure the internal liquid temperature during active fermentation and compared that with what the cheaper temp gauges might be reading?

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Old 11-11-2009, 05:07 AM   #2
oldschool's Avatar
Aug 2009
southern IN
Posts: 708
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I have yet to actually test your thoughts by observing the temp strip Vs using an internal thermocouple. On the other hand I've seen the temp strip display 3-8 degrees warmer than the ambient temp for the first few days then slowly drop back down to ambient air temperature. I have one now that's been in the primary since saturday night and we're having to keep the room temp in the low 60s to keep the strip reading 68ish. I think that the surface of my fermenter is conductive enough to display the actual internal temperature close enough to keep everything happy. I doubt i've answered your question. I'm sure someone like Pol will put in his two cents worth...

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Old 11-11-2009, 05:39 AM   #3
Blender's Avatar
Jan 2006
Santa Cruz, CA.
Posts: 3,106
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Those fermometer strips are pretty good.I think they display an accurate enough temperature of the liquid inside to rely on them. Just don't get them wet because then they get screwy.

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Old 11-11-2009, 05:42 AM   #4
Palefire's Avatar
Jun 2009
Posts: 1,124
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I haven't tested the strips either, but there are a lot of threads around here where people say they have, and that fermometer strips matched pretty well with the internal temp of the liquid.

I do know that lots of the big names here use them, and that they seem to be happy with their beers!

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Old 11-11-2009, 03:43 PM   #5
david_42's Avatar
Oct 2005
Oak Grove, Oregon, USA
Posts: 25,599
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A bunch of tests were run 2-3 years ago and the temperature of the strip accurately reflects the wort temperature. Even a plastic bucket is more conductive than air.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"

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Old 11-11-2009, 05:05 PM   #6
Aug 2008
Portland OR
Posts: 5,387
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I am currently fermenting in a 15 gallon Corny style keg. Checked the temps of the side of the container last night and at the bottom it was 61F and near the top of the liquid level it was 70F. Moral of the story is knowing where to measure and no matter what you do you are going to end up with beer.

In the past using a thermo strip I found it to be accurate pre & post active fermentation.

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Old 11-11-2009, 07:00 PM   #7
DKershner's Avatar
Jul 2009
Bend, OR
Posts: 1,870
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In case the other 7 posts weren't enough, general concensus is that the outside of glass/plastic/stainless containers is within 1 degree of the internal temperature.

Secondly...your name looks familiar...

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