I’m learning how to home brew and saw temperatures that I did not expect, its a long description of what’s going on but I appreciate seasoned veterans’ opinions:
I’m brewing 5 gallons of honey porter in a plastic fermenter bucket. The bucket has a liquid crystal temperature strip on the side, it also has one thermocouple taped and insulated with foam placed nearby. A second thermocouple is placed in a one gallon container of water, that container has a lid to prevent evaporative cooling, the temp strip and both thermocouples are all at about the same height.
The fermenter and 1 gal water sample are all inside an insulated bag, I’m using ice bottles to keep it cool and temps have been very steady. The bucket measurements, thermocouple and temp strip, are consistently the same. The water thermocouple is typically about 2-3 degrees warmer than both measurements on the bucket.
I would have expected that to be the other way around and the bucket would be warmer than the water. My theory is that the ice bottles are touching the fermenter, which even though it’s plastic, that contact is providing direct cooling vs the water which only cools from the air inside the insulated bag. Ive confirmed it’s not the thermocouple, there’s an actual and consistent temp difference. I wonder what experts think?