Another beginner question about temperature

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Well-Known Member
Mar 12, 2023
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I have a wifi thermometer attached to the side of my fermenter. I also have another in the same room a few feet away from the fermenter. When a certain yeast gives a temp range for a wort, such as 59-73F, should I use the room temperature thermometer or the one on the fermenter to gauge the correct temp for fermentation? I have heard that active fermentation can cause a reading of as much as 10 degrees higher at the thermometer attached to the fermenter. Cheers!
The temps given for the ideal range of temps is the wort/beer itself. But usually it's only a very brief period that the beer in the FV is over the ambient air temperature.

I haven't had any ales or porters stay at the top of their ideal fermentation temp for much more than a day if that long before going back down to near ambient air temp. Only one ever got so warm that I resorted to actively cool the FV for a short time.

I only do 1 to 2½ gallon brews of beer. So with bigger 5 gallon or more, YMMV.
the temp of the fermenter is what matters most. yeast can is temperamental depending on the yeast which is why it's important to pay attention to the yeast label, temperature control is a real thing