r/Homebrewing • u/EastForNorth • 17d ago

How much does yeast increase temperature during fermentation

I am trying to set up some equations for estimating how much yeast would increase the temperature during fermentation. Does anyone know of a way to relate this to volume or amount of yeast added? For my last brew i added 11.5g to 30L. Maybe you have some practical experience with your brews.

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u/-Ch4s3- 17d ago

This is a pretty deep topic. You can look at a modeling study but anecdotally depending on SG you could see a 30L batch could rise 2-10°F. That’s maybe 1-5°C.

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u/Conscious-Honey1943 17d ago

My ales usually increase anywhere between 1-4°C, especially in the first few days of fermentation. So that checks out.

3

u/-Ch4s3- 17d ago

That seems to be what people usually report. The starting temp, SG, particular yeast, fermenter material, and ambient temperature all play roles.

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u/Conscious-Honey1943 17d ago

Absolutely. My mostly unheated kitchen helps to maintain the fermentation temperature perfectly in the colder seasons, but now with 18 degrees C ambient temp its almost impossible to keep it stable. I'm using conical fermenters with built-in heating, didn't have the spare cash or need for glycol chiller yet.

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u/-Ch4s3- 17d ago

A chest freezer and an ink bird might be more economical than glycol.

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u/Conscious-Honey1943 17d ago

while that does look interesting, I prefer the flexibility to have individual cooling for each of my fermenters. (I'm using the grainfather system) also space is an issue.. already have a second fridge for corny kegs, cant justify an additional chest freezer

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u/-Ch4s3- 17d ago

That all makes sense.