For the purposes of studying this batch I put an additional digital thermometer (the same red one that you see stuck to the propane tank in one of the pictures below) into the chamber to measure ambient air temperature. In addition, my kit came with a stick-on "Fermometer" which has a mood-ring like ability to indicate temperature, so I applied it to the carboy as well. I also got a standard mercury thermometer in the kit, so what the hey, I tossed it in as well.
Here's what I found this morning:
- The digital thermometer reads 73 F
- The Fermometer reads 66 F
- The mercury thermometer reads 66 F
- The temperature probe reads 60 F
Conclusion: I'm obsessing over this too much.