Very little temp rise during fermentation

[pc_trott]

I am a week into my first brew (Block Party Amber Ale). I have read many reports, in this forum and elsewhere, that one can expect the working yeast to raise the temperature of the wort up to ten degrees. I added yeast to my primary when the wort temperature was between 64 and 65F degrees. (The ambient temperature of my basement hovers +/- 2 degrees of 60F.) The fermentation took off overnight, and for two days the airlock was bubbling like mad. Then it slowed down, and by the fourth day was bubbling an anemic once or twice a minute. I understand (I hope correctly) that this is normal. But my question is, should I be concerned that the temperature of the fermenting wort never went up more than a degree or two from the temperature at which I pitched the yeast? The layer of foam on top of the wort never got more than 3/4 of an inch thick, either. I was expecting to have to be ready to switch over to a blow-off tube at any minute, from what I'd read. Should I be worried?

 

[TechFanMD]

How do you measure temp?

If it is a stick on thermometer - that's just measuring the wall of the fermenter and may be different than the actual liquid temp depending on conditions. If you have decent airflow (from your HVAC or other means) it also keeps the fermenter closer to ambient temps and will not allow a change in ferm temp....my goal.

A thermal load rise during fermentation happens 100% of the time....whether the wort changes temp is a matter of temp control whether wet towels, a fan, a ferm chamber, or whatever.

 

[pc_trott]

I am using a stick-on thermometer, but I also have a wrap-around heating element attached to the carboy, which I set to 64 degrees F, and it and the stick-on have been pretty much in sync. I also have the fermenter wrapped in a thick towel to keep the heat in. I was told I should raise the temperature on the heating element to the low 70's during the last week of the ferment to keep the yeast active. But perhaps, as you are suggesting, the brew was warmer than either of my external thermometers were able to read?

 

[TechFanMD]

I am using a stick-on thermometer, but I also have a wrap-around heating element attached to the carboy, which I set to 64 degrees F, and it and the stick-on have been pretty much in sync. I also have the fermenter wrapped in a thick towel to keep the heat in. I was told I should raise the temperature on the heating element to the low 70's during the last week of the ferment to keep the yeast active. But perhaps, as you are suggesting, the brew was warmer than either of my external thermometers were able to read?

I'm suggesting that ambient conditions must have kept it cool

 

[RM-MN]

The temperature rise you get in the fermenter depends on how vigorously the yeast are working. How vigorously the yeast work depend on the temperature so that if you start the ferment at 75F and don't control the temp rise it can be up to 10 degrees. Since you started the yeast much cooler they work slower and you won't see as much temperature rise. I typically start mine at 62F and never see more than 2-3 degree rise even without active temp control.

 

[Buick Beer Gardens]

I start mine between 62-64 degrees. Visibly active fermentation is seen in about 48 hours at that temp. The activity gets more visible in 72 hours. The temp does not rise much. Controlling the temp at 62-64 degrees prevents me from needing a blow off tube. The bubbler burps a bubble about every second when the yeast are active and swirling around in the fermenter.

 

[Saunassa]

Where I ferment in winter it is 60-62 degrees. I had a fermenter with heat wrap and thermo-well and a t-shirt over it. Temp set at 65. When very actively fermenting the temp went up to 66 and stayed there needing no help from the wrap. Probably kept itself there around 12 hours. Amazing little beasties.

 

[DVCNick]

Of course ambient temp will have a large impact on wort temp, so what you are looking for is to keep the wort temp where you want it through controlling the ambient temp one way or the other (fridge, water bath, whatever it is).

When people are talking about temp rise from fermentation, they are talking about the differential between the wort temp and ambient temp; the heat generated by fermentation is responsible for this delta. I believe that is what you are talking about, but I just wanted to clarify.

My personal experience is also that the amount of heat generated is often overstated. I use a thermowell to measure the center of the carboy where it should be hottest, and I don't keep very careful notes on this aspect, but during high krausen with, say US05 I'm usually shooting for mid to upper 60's wort temp. About 5 degrees of differential is the highest I can ever remember seeing. I'm sure there are a million variables that could impact this; batch size is probably one of them as well, so... I'm talking about five gallon batches, fwiw.

 

[Kaz]

Your 60F basement kept the fermentation temp in check. Congrats, in the summer here, I have to use a refrigerator, I wish I had 60F basement all year long. If you had pitched at 65F and put the fermenter in a room that was 65F, you would've seen a much more dramatic increase in temperature. A slow temperature controlled fermentation will usually not result in the high temp swings that you hear about, of course this depends on the yeast, the wort gravity, nutrient levels in the wort etc. Either way, an Amber Ale fermented at 65F should be nice and clean, enjoy!