Temp Caused By Fermentation....

Are the high temps caused by the fermentation itself ever taken into consideration? For instance, I have a beer fermenting in a room that has varied 65-67 however, shot with a heat gun, the Carboy is at 78*. It's in strong ferment mode 2nd day. But it's still temp. Just wondering if this is the norm or do I have to ferment at lower ambient temps?

Yes, most of us take that into account. You can get a cheap "fermometer" that will read the temperature on the carboy. And if you're using active temperature control, insulating the temp probe against the carboy is generally the best option.

What yeast are you using? A beer temp of 78 can produce some pretty nasty fusels. Also keep in mind that those IR thermometers can be fairly inaccurate, unless you input the specific emissivity of the surface.

Catfish1320 said:

Are the high temps caused by the fermentation itself ever taken into consideration? For instance, I have a beer fermenting in a room that has varied 65-67 however, shot with a heat gun, the Carboy is at 78*. It's in strong ferment mode 2nd day. But it's still temp. Just wondering if this is the norm or do I have to ferment at lower ambient temps?

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You need to account for this increase - all the temps listed for yeast and in recipes usually mean fermentation temp (i.e. the temperature of the beer) and not ambient temp. Still, an ambient temp of 65°F should be fine...an increase of 13°F seems high. Is your heat gun calibrated?

Yes, the yeast in their activity create a lot of heat. I don't know anything about heat guns, so can't comment on how accurate that is. You could get a stick-on strip thermometer and attach it to the carboy and that will give you a sense of the temperature inside it. I use a temperature controller and a chest freezer, and attach the probe of the temperature controller to the carboy - I stick it snugly underneath the webbing of the carboy carrier I use, so its held tight against the glass. For most of the ale yeasts I use, I start the fermentation temps at 60F and raise it up slightly as fermentation continues.

Before my current setup, I used a big rubbermaid bin in my basement - ambient temps in the 60s - filled the bin with water and put the carboy in it, then swapped out 1/2 gallon frozen juice bottles. I kept a floating thermometer in the water and aimed for 58-64.

The yeast is wlp001. I was really surprised to see it that high also. I'm hoping the gun is just off. It's a good gun, but been around a while. Just in case, I moved it to another cooker area, and will be getting stick on thermometers real soon. Probably too late to worry about this one, but lesson learned.

Yes yeast generates heat. From my experience if the ambient temp is near or below the low end of the recommended range for that yeast, the temp rise is usually only a few degrees. If the ambient is near or above the upper end of the temp range the temp rise can be 10 or even more degrees higher. I always like to start off at the lowers end of the temp range. The ferment is much easier to control that way.

140 kcal/kg extract

10 lbs of grain is 4.54 kg, x .85 =3.86 kg extract which would yield 540 kcal.

540 kcal would raise the temperature in 19L (5gal) 28.4 °C ( 51.1 °F)

So there is enough energy to heat 5 gallons by fifty degrees Fahrenheit. Which is to say if the reaction occurred in zero time, if it went off like a bomb, that’s what would happen.

I ferment in a water bath and in a well controlled fermentation the beer will be as much as 1.0 °F warmer than the water bath in the first few days. That’s measured with a calibrated thermometer in a thermowell. I don’t know what it would be in air, my guess is 10 times that.