Dial setting for freezer thermie?

[Monk]

I've used a thermostat controlled freezer to ferment for years, but I always set it at ~62F. I want to be on the safe side, knowing that the fermentation will increase the temp of the liquid. I've not had any problems with that technique, but I don't know exactly what temp I'm fermenting at, either.

For those who use a temp controller, how do you know exactly what temp you're fermenting at? I'm brewing a Fullers ESBish bitter and want to ferment around 68-69F, how much temp increase do you think the yeasties will cause?

monk

 

[Hex23]

If you read about the exothermic nature of yeast fermentation you'll find quite a wide range of temp increases cited. And the temp increase depends on alot of conditions. You might be able to say that it averages 3-5F? and just set accordingly.

If you're really concerned about getting the exact temp, you could buy a thermowell. It's a stainless steel rod-shaped cavity that sits in the wort/beer, into which you can place your temp probe. The second best thing would be to fix your temp probe to the side of the fermentation vessel, with an insulator over that.

 

[Monk]

Do most of you set your thermie a few degrees lower than your intended ferm temp, or stick the probe to the fermenter and dial it in to exactly the temp you want to ferment at?

 

[Tanagra]

Do most of you set your thermie a few degrees lower than your intended ferm temp, or stick the probe to the fermenter and dial it in to exactly the temp you want to ferment at?

(Lengthy but informative)

When I first started brewing lagers, I bought a chest freezer with an external thermostat (dial). The probe 'hangs' in the middle of the freezer and is not in contact with anything but open air.

I received a 'weather station' device as a gift, and decided it would be a great idea to put the transmitting end inside the chest freezer to double check the accuracy of the dial thermostat. This proved to be an invaluable device, as the dial is not very accurate. I now even use the chest freezer for fermenting my ales as the temperature can be calibrated so precisely.

Once I dial in and adjust the dial over the course of two or three days with the help of the weather station, I am able to get a perfect 3°F swing in temperature. After every adjustment and subsequent temperature rebalancing (about 6 hours of wait-time), I simply reset the stored temperatures and the weather station starts downloading and storing new samples (every five minutes). After a day or so of samples, the weather station will tell you the 'coldest' and 'warmest' temperatures that it received - the average of the two is my actual ambient temperature for fermenting purposes.

It wasn't until I bought a stainless steel conical fermenter with a thermowell that I actually believed that the temperature rises so greatly during fermentaion - especially during high activity. I noticed that while the fermentation was most active, the beer in most of my ales was ~5°F warmer than the ambient temperature, and slightly less with lagers (due to the naturally less rigorous and colder fermenting temperatures of most lager yeasts).

Since nearly all yeast strains have at least a 5°F swing of optimal temperature range, I set the chamber to the very low end of the scale and let the beer ferment. This way, at the height of fermentaion, the beer will not breach the high temperature threshold. Once the activity slows and the beer nears final gravity, I turn the dial 10°F warmer for diacetyl rest and to keep the yeast from flocculating early, then decide where to go from there - spunder/rack/secondary/cold crash/condition/filter/whatever.

Short answer - YES! Set to 5°F lower than you want the beer to ferment at during its most active state, and then after fermentation slows, raise the temperature by 5°F.


Hope this helps!

John Quasarano

 

[Monk]

Hope this helps!

John Quasarano

Heck yeah this helps! Thanks for taking the time to type all that out, brother. :rockin:

 

[Seanwallner]

Very helpful. Thanks John!!

 

[GilaMinumBeer]

Do most of you set your thermie a few degrees lower than your intended ferm temp, or stick the probe to the fermenter and dial it in to exactly the temp you want to ferment at?

I have a thermowell that fits through a bung or through the grommet in a bucket and is sized such that my thermister slides just inside. So, I set my controller to the temp that I want the beer to ferment at and let my controller either cool or heat as is needed to maintain that temp.