Bubble wrapped and bungied to the fermenter works fine for me. The bubble wrap keeps it from detecting ambient temperature swings too quickly and cycling too often. I use the thermowell on my wrap heaters for ales, but the bubble wrap and bungies or string tie to hold it in place for cooling lagers in the fermenting chest (painter’s tape may work, as well, but I have found that it doesn’t want to stick well to cold containers and I start pretty cold with lagers).
:cheers:
