Originally Posted by Rivenin
with a carboy full of wort and the fermometer on it. i haven't had an issue with temp yet. did you perform the test with it empty? or with a bucket/carboy in it?
I tried it both ways, empty and with a water-filled carboy. The carboy temp was obviously much more stable than the air temp and stayed within about a 5°F range over 24 hours (this is with the probe taped to the side of the carboy and insulated). The top of the carboy was 3-4°F warmer than the bottom. During fermentation, when the wort is constantly moving, I'm sure this wouldn't be an issue. I'm just really anal and it bugged me, so I added the fan and an external temp controller so I could keep the temp fluctuations to <1°F and maintain a stable temp during active fermentation.
Mind you this is with a pretty large fridge with thin walls (the 52-bottle Vissani that Home Depot sells). A smaller, better insulated fridge might be just fine without the fan.