Heat of fermentation

[hoppyscotty]

I have a large fridge that I've converted into a fermentation cabinet. For heat I have two greenhouse tube heaters, one is 60w and one 40w I think, so 100W total power. Last weekend I did an IPA with Kveik yeast and set the Inkbird to 32C and pitched the yeast at around that temperature so right from the get go things were fine and temperature has been maintained well since and the yeast was happy and active within a few hours.

However just gone to it today to take a FG reading and the temp had dropped down to 13C. Thought initially it was because I'd opened the door of the fridge and let all the heat out, then remembered I have a thermowell so that temp is right in the middle of beer and sure enough the beer felt cool to the touch and the heating tubes were on and hot. Also noticed the fermenter had sucked in a bit (Fermzilla) so the temp drop had not just happened since I'd opened the door. Ambient temperature in the room is around 17C today, but might have been cooler overnight when the fermentation probably ceased.

FG is there or there about - a few points off 1.016 instead of the targeted 1.012, but was a few points up on OG so I'm calling it that fermentation is finished...but this begs the question are my heat tubes man enough for the task? Was the temperature being maintained purely from the heat of fermentation rather than maintaining temp from the heaters? Does fermenting yeast give off that much energy? would my heaters be man enough if it were winter and the ambient temperature closer to zero? Thanks

 

[An Ankoù]

Your ambient temperature is 17 but the beer was 13C.
You haven't got the fridge turned on, have you?
Sorry, but it has to be asked.

 

[hoppyscotty]

Your question prompted me to check. Oddly the fridge is on...so the ink bird was in heating mode with the heaters on AND the fridge was on but not supposed to be, so in a battle between fridge and heaters the fridge wins!

Odd, must be a problem with the ink bird, but its been happy sat at 32C since the weekend!! Maybe heaters plus fermenting action beats fridge!

Just unplugged the fridge and will see if temp begins to pick up. Now at target FG anyway after the sample has warmed to 20C so calling it anyway. Will get one more day of hop utilisation from the dry hops at a warm temp before plugging the fridge in and cold crashing. But looks like a strange Inkbird issue.