Temp Control Questions

[jb1677]

I have been trying to get better with my fermentation temperature control. For my first 5 or 6 batches of ale I simply put the fermenter in the basement where ambient temp is ~68 year round. The results were decent but in the quest for better beer I decided I needed to lower the temperature figuring 68 ambient would mean 78ish in the fermenter.

To accomplish this I started placing the fermenter into a tub of water, basically up to the level of the beer enveloping the fermenter by 3" - 4" of water on each side. I use ice to keep the water ~60 - 65 and the results have improved.

My question is, when surrounded by cool water, how much higher should I expect the inside of the fermenter to be, still +10 like when fermenting in open air our would the temp be closer to the water?

I know a thermowell or similar reading inside the fermented would be best, but for now is there any science that can help explain the temp inside the fermenter?

 

[daksin]

It's going to vary depending on the beer and the yeast. Those stickon thermometers are super cheap and actually fairly accurate if you don't get them wet. I just put a bit of packing tape over them to protect against splashes and just make sure the thermometer is under the beer line but above the water line.

 

[progmac]

for many yeasts, i have noticed that the exothermic heat produced is substantially less once you get below about 65. when i ferment at 62-64, the wort seems to be 65-68 at peak activity. on the other hand, if i ferment at 68, the wort is easily 75+. some yeasts (RINGWOOD i'm looking at you) seem to take wort all the way from 62 to 70+, but these are the exceptions. the water bath is going to buffer this even more so i would think. i love daskin's idea of a protected stick on thermometer.

 

[jb1677]

I tried the stick on thermometers but learned as you pointed out they don't like water. I tend to keep the water level at the beer level, the more water the easier it is to maintain a steady temp AND in my mind if a portion of the fermenter was not protected by water that area would get warmer than the area protected by water.

I see a thermowell of some sort in my future

 

[Wynne-R]

I use water cooling up to the level of the beer and I find that the temperature difference for a well controlled fermentation peaks at about a degree Fahrenheit.

If the water is up to the level of the beer, the water temp tracks pretty well with the beer.

I have two thermowells, but I seldom use them. If I’m doing some sort of experiment I might do it, but not for a routine fermentation.

Using the water bath temp is easier and safer.

 

[AnOldUR]

Like Wynne-R says, if the immersion level is the same as the beer the difference will be negligible. Especially if you have some type of circulation. I use a cheap little fish tank pump to keep the water moving.