I did my first brew 2 days ago, and I’m quickly learning that controlling fermentation temperature is not necessarily as easy as I expected it to be. I’m storing my carboy in an unfinished/unheated (but insulated) room that has been in the mid-60’s F for the last couple of weeks. My wort was 65 F when I pitched (Danstar Windsor yeast 64-70 F optimum temp).
12 hours after pitching, the fermometer on the outside of my glass carboy had risen to 68F. Lots of active fermentation.
24 hours after pitching, the fermometer was at 72 F and decided I would need to do something to bring down the temp. I made a swamp cooler for it.
36 hours after pitching and 12 hours in the swamp cooler, the fermometer was back down to 68F. I go to sleep, check on it 7 hours later, and the fermometer is down to 60F, and there’s much less fermentation activity. Thinking that 60 is too low, I pulled the towel off it and turned off the fan before leaving for work this morning.
A few questions for the more experienced brewers here…
How will temp swings like this effect the the finished product?
Is there a danger of the yeast dying when it’s down at or maybe below 60F?
How accurate are the Fermometers? I’m guessing the liquid inside might actually be a couple of degrees higher than the Fermometer reading, but wondering if anyone has tested.