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What temp is my beer?

Do fermento meters reflect the rise in tempeture caused by fermentation? Does anybody know of any experiments where the rise in temperature during fermentation is proven. Everyone says it but I’m searching and not finding any studies or tests. I’m sure some Homebrewer/ scientist has a blog where the change in temp change is documented I just can’t find it. Any help?

The temp rise is going to vary widely based on volumes, fermentation vessel, etc. I do trust the fermometer to pretty closely read the temperature of the wort and I do think others have verified < 1 degree difference from the center of the carboy. In my experience the max difference between fermentation temps and ambient has been max ~5 degrees when I’ve got a very vigorous fermentation. I’ve been able to get that temp difference to be even more by wrapping the carboy in a blanket.

At home I do have a link to a real experiment. If memory serves, the center of a fermenter is like 2-3 degrees warmer than ambient at peak krausen. So, yes, there is a difference, but not huge.

Over on the HBT forum, there is a major discussion by two heavyweights in the homebrew field- AJ vs. Wynne( Engineer vs. Physicist). I think the thread is called ‘Thermodynamic help’ or something like that. Gets pretty thick, but this is what I took out of it:
1.Yes, definitely fermentation is an exothermic reaction and will generate heat, the amount depends on the size of your container and the circulation of the wort/beer in the fermenter.
2. That heat will transfer to the sidewalls of the fermenter in order to try and equalize with the environmental temperature.
3. If your fermenter is sitting in a swamp cooler that is cooler than the beer, then that heat will be transferred to the water bath. The rate of transfer depends on the conductivity of the walls of your fermenter(metal best, glass good, plastic the slowest) as well as the circulation of the water bath, and the circulation of the beer.
4. So, in practical terms, yes swamp coolers do work. You want to keep the water bath at least a couple degrees below your target temperature. The fermentation process generates a circulation so you’re OK in there, but generating a circulation in the water bath helps some.
Made me feel pretty good about my process since I rely on swamp coolers for all my temperature regulation needs.

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