how's this for interesting?

[Papagayo]

So I'm fermenting some fresh cider I froze last fall, and right now I'm around 1.035 and in fervent primary fermentation. Tonight I went down to check temperature and gravity and got some very interesting measurements. SG is going along as predicted, but, here you go, the temperature of the must registered at almost four degrees above room temperature. I check numerous times with reliable equipment, and this is a small room with basically no variation in temp (i.e. there is no heating vent below my fermenter).

So what I'm wondering is if the movement of the CO2 bubbles through the must is actually raising the temperature of the must. If so, this would seem to have a possibly significant effect on how we go about gauging temperature during fermentation, in that, must temps during intense fermentation could go well above room temps.

Any thoughts?

 

[Hang Glider]

You state it is "fervent primary fermentation" - it is not the movement of CO2 bubbles necessarily, but yeast's metabolic activity during active fermentation will most certainly raise the temp of what it's fermenting (wort or must) from 4-10F. Yes, as high as 10F...in my own personal experience.

So, yes! we must gauge temperature during fermentation. For those using chambers of some description that employ temperature controls - the probe should be taped to the side of the fermenter and insulated against the ambient temps. For those using a water bath, the temp rise is much less significant, as AIR is an insulator, while WATER is much more efficient at moving thermal mass. A small inexpensive pond pump dropped into the water bath makes it much more efficient.

 

[BryanThompson]

Or you can use this for the most accurate tempurature of the fermenting liquid.