Revelation: taping to the side of a fermeter doesn't do a great job for me. ACTUAL REAL-LIFE PIC OF FERMENTER SHOWN BELOW -
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I scored this fridge last week which has an internal circulation fan - perfect (found on the side of the road, the owner said "it's no good, it freezes things all the time and we couldn't fix the temp adjuster thing". Whimmy-wham!).
- I set my STC-1000 to 10°C for my pilsner. Yeast nutrient, 02 for 1 min. Noted activity after 12h.
- Day 2 - not much action. Check SG which had dropped 3 points. Bumped temp to 11°C
- Day 3 (yesterday) - just beginning to see krausen.
I've noticed that the 'new' fridge seems to run a lot for a fridge trying to achieve 11°C.
Considering it should be well underway by now I put a glass (which you can see in the pic) next to the fermenter with my thermometer in it. I left it for a few hours and came back to see it sitting at 6°C. As far as I'm concerned the two liquids should be the same because the air is being recirculated. This explains the slow start, and I gave the pilsner a gentle stroke to show my appreciation that even though it was at 6°C, it was still fermenting.
I had my STC-1000 adjust to +1 so in effect it was set to 10°C, but still controlling 4°C lower than set value. To account for this I've adjusted the offset but it goes to show that it's hard to trust the sensor if it's not submersed.
Yes, I have checked the accuracy of the STC temp probe with my thermometer before and yes, I will be buying a submersible probe tonight. Life's too short to gamble with pilsners.