Primary ambient temperature?

Does the fermenting process generate significant heat? The reason I am asking the question is as follows:

a. If the primary is generating heat from the fermenting process then I will adjust my planned floor freezer temp to recommended yeast ranges to compensate for the actual temp on the primary.

b. This I assume would best be accomplished by placing a thermometer on the outside of the primary.

c. Assuming the primary is warmer by lets say 10 degrees. Then one could adjust the freezer temp to lets say 57 degrees to ensure the primary remains at 67 degrees. This assumes the fermenting temp range for the wort would be 65 to 70degrees.

Here in south Texas tempature control during the summer is extremely difficult to manage. So my brother and I are starting out focusing in on this issue before we even get started. We are planning a combination frig freezer set-up to handle our primary, secondary and storage needs.

Thank you in advance for your response.

You will find that this varies according to yeast strain, how much yeast is pitched, and how vigorous the fermentation is.


But as a general rule, you can expect the wort to be about 3-5 degrees above ambient temp during the most active period of fermentation. This will taper off as the vigor of the fermentation tapers off.

Then is it really necessary to monitor primary fermenting temp?

Yes- if the room is warm and the fermentation is strong, it will get too hot. Try to keep it in the range that the yeast likes best- that should be on the package. For example, California ale yeast:
Attenuation: 73-80%
Flocculation: Medium
Optimum Fermentation Temperature: 68-73°F
Alcohol Tolerance: High

I'd try to keep this one at the low end of the optimum temperature, around 68 degrees. If it gets up over 73 degrees, I'd cool it down a bit. I don't have a fridge with an external controller, so I'd do the "swamp cooler" thing or put it in the basement, or use my big igloo cooler. (See my gallery for pics of that cooler set up). Of course, I live in a cool climate so it's really not a big issue for me.

bpcsatx said:

Then is it really necessary to monitor primary fermenting temp?

Click to expand...

Absolutely. I'd say that fermentation temp control is one of the critical issues in making good beer. If you shoot for the lower end of the suggested temp range for your yeast strain in most cases, you should be good to go.

I make sure the ambient temp is never above 65 degrees during fermentation. This way, even a 5 degree temp increase will only bring me to 70 deg which is still in the range for all the yeast strains I typically use.

Thank you all for the detailed responses. We plan on using the floor freezer as our primary fermentation cooler. I like the Ranco temp controller the best to regulate both the frig and freezer.

I wanted to ask what is the most accurate way to monitor your primary fermentation wort temp? I would assume that most are on the outside of the fermenter which would have to be adjusted for actual internal temp.

Well the little strips on the outside of the carboy are ok- during fermentation, things are swirling around pretty well, so it's a fairly accurate way to tell while keeping your beer protected.

I went to wal-mart and got a bunch of those aquarium themometers (fish and ales like about the same temperature range). There were only a buck each and work great, they read a few degrees above during active fementation, and the same as ambient temp after fermentation subsides. So cheap, I got them stuck all over my fermenter so no matter which side I look at it, I can always see the temp.

The experiment has been done and the temperature on the outside of a fermenter is very close to the inside.

What I do is tape the Ranco probe to the side of the fermenter with a piece of foam (cheap sponge) over it or put it under the fermenter. You can purchase probe wells that let you have the probe inside the wort.

I think if you are doing 5 gal batches and keep the temp at the bottom of the yeast's range you should have no problem. If you using a larger fermenter or perhaps if you rack a high gravity wort onto a yeast cake then you will have to be more concerned with the fermentation temp.
I still have to warm my basement up to Ale temps so keeping it at 65F is no problem.
Craig

i prefer the bottom of the range myself no matter what, and figure if it goes a few over the bottom than i'm doing fine.

spices > esters