How much heat does fermentation produce?

[ARittner]

So, every time I do a batch of beer something goes wrong. Nothing so bad as to ruin the beer, but enough so that I know what to do to correct it for next time. This past batch had issues with temperature. Namely, the heat failed in my house and the ale was in the low 50's for a day before I knew.

I went ahead and made the investment in an 8 cubic foot chest freezer off of Craigslist, a Johnson Controls temp controller, and some other stuff. I figure this way I'll be able to keep it warm enough in winter, and cool enough in the summer.

My basement, on average, is about 50-55 degrees in the winter. I was going to do the lightbulb in the freezer trick to keep the air in there warm, setting the temp controller to keep it about 64 or so. The freezer itself would be plugged in obviously, just using it for it's insulated properties.

If the ambient temp is 55, would that even be needed? Is it possible that the heat from fermentation in a closed chest freezer would keep the air inside at the desired temp? I guess my only worry is I'll have the thing all set up to keep the beer warm, but should I consider that I may actually need to keep it cool?

I know, I won't be able to get a real answer from this until I actually go and do it. But I was wondering if anybody knew about how much heat to expect, or had run into a similar situation.

Thanks!

-Andy

 

[downinit]

Do you expect to loose power alot? If not you can just get a fermentation heater that wraps around your bucket or carboy. They are designed for just this purpose.

 

[Delorean1981]

Rough math, depending on attenuation, say at 100%, 5 liters (1 gallon) of ethanol contains roughly 100 MJ of energy. So in a 5 gallon batch, about 500 MJ is collected, equating to 475k BTU's. While sleeping, humans produce about 250 BTU's / hr.

If the full 475k BTU's are collected over a standard 2 week period, 24*14=336 hrs, 475/336=1.4k BTU's per hour of heat generated by the yeast. So for a standard 6 hrs of sleep a human produces the equivalent heat the yeast do in 1 hr. That's at 100% attenuation.

Unless I'm completely off..

 

[idigg]

Has anyone ever made a fermentation box made out of rigid insulation that could fit 2 fermenters? Would this help if someone's ambient temperature in basement was 60*F? I wonder if you made a "box" out of rigid insulation to hold a fermenter, if it would be warmer inside.

 

[bmbigda]

So, every time I do a batch of beer something goes wrong. Nothing so bad as to ruin the beer, but enough so that I know what to do to correct it for next time. This past batch had issues with temperature. Namely, the heat failed in my house and the ale was in the low 50's for a day before I knew.

I went ahead and made the investment in an 8 cubic foot chest freezer off of Craigslist, a Johnson Controls temp controller, and some other stuff. I figure this way I'll be able to keep it warm enough in winter, and cool enough in the summer.

My basement, on average, is about 50-55 degrees in the winter. I was going to do the lightbulb in the freezer trick to keep the air in there warm, setting the temp controller to keep it about 64 or so. The freezer itself would be plugged in obviously, just using it for it's insulated properties.

If the ambient temp is 55, would that even be needed? Is it possible that the heat from fermentation in a closed chest freezer would keep the air inside at the desired temp? I guess my only worry is I'll have the thing all set up to keep the beer warm, but should I consider that I may actually need to keep it cool?

I know, I won't be able to get a real answer from this until I actually go and do it. But I was wondering if anybody knew about how much heat to expect, or had run into a similar situation.

Thanks!

-Andy

It's not necessary to figure out just how exothermic fermentation is. All you need to do is attach your temp. controller's probe to the side of the bucket/carboy, and cover it with a folded up paper towel or similar insulator. I also cover the paper towel with duct tape but that may be overkill. You will now have your temp. controller reading the beer temperature, not the ambient chest freezer temp.

Of course if your temp. controller does not have a probe, it's another story. If that's the case you can only get so close, because the heat generated by fermentation is going to start high and steadily decrease, and at a different rate depending on the yeast strain and recipe of the beer.

 

[RM-MN]

How much heat is given of by fermentation is influenced by how fast the fermentation is which is in turn influenced by the temperature of the wort. I fermented my last 3 batches with an ambient temperature of 61 F. and at the peak of the ferment, the thermometer stuck to the outside of the fermenter showed 63 and then it subsided back to the 61. If your wort was warmer, the ferment becomes faster and you'll see a greater temperature rise.

 

[ARittner]

Do you expect to loose power alot? If not you can just get a fermentation heater that wraps around your bucket or carboy. They are designed for just this purpose.

I could, but I was going to use the freezer to keep the beer cool in the summer, when the basement hits about 75 or more. Besides, I already have it. I do have the temp controller with a probe too. I'll just have to keep an eye on it I guess, and see if its getting too warm.

 

[Sacreddog717]

You could add a space heater on its own temperature control like this one. http://www.williamsbrewing.com/BREWER_S_EDGE_SPACE_HEATER_P518.cfm

 

[munche]

Well, I'll give examples from my setup.

When I put a 1.080 beer onto a full yeast cake, I had my fermenterator at 65 ambient. The beer got up to 74 by the next morning, according to the Fermometer sticker on the side of the carboy.

I use a 2 stage digital temp controller to keep both heating, and cooling. Since my freezer has room for 4 carboys, I don't monitor off of a particular beer, but just sort of keep an eye on the temps and adjust the controller accordingly.

After looking everywhere to try to figure out how to heat the area (reptile heating element! light bulbs! fermwraps!) I bought a $14 space heater fan from Wal-Mart. Heats the whole thing up 10 degrees in 5 minutes if I leave it on. It's on the controller now and clicks on on those really cold nights. Works great.