Difference Between Fermentation and Ambient Temps?

Hi all! I'm active in the beer forums but I'm doing my first KT today. Using a SCOBY from a friend and doing a 2L batch.

I know that it's not uncommon for fermenting beer to rise up to 10F above ambient temp, but that's also a lot of yeast activity. Is kombucha similar? Since I can't keep a thermowell in the beaker while I'm brewing it (metal), I'm wondering how to dial in the temperature I want.

I know kyt says he uses a water bath and an aquarium heater. If I do something similar, should I set it at 74F (target ferm temp) or lower to account for heat produced by the yeast?

I'm sure KYT will jump in if I'm off base but I just tape the thermocouple to the side of the glass jar with some insulation on the outside so that I'm sensing the heat closest to the KT. I've taken readings outside the glass and inside the KT so I know the differential. I have 6" heat wrap around my brew so it's fairly consistent temp around it. Not as good as the water method but it seems to brew tea just fine and I don't really have any significant temp change per se during an active ferment. At least not something I'm worried about spiking up Beyond the ability to control it simply. It's more of a gradual change.

You'll want to set it to a couple °F above target temp. That's the point where the heater will shut off, and air will cool it back down. Unless your air is hotter than target lol
However, if your water does not move, then only the heat convection current is all you have and that isn't very efficient. You can expect the water within an inch or so of the heater to be about target but the rest will be a couple to several degrees cooler. This all depends on total volume and dimensions of the bath of course. KT typically is not as vigorous as beer so you don't have to account for much difference between in/outside the jar. They'll be close enough. Just make sure the bath water level equals the jar fluid level. Don't exceed it or the jar will float and potentially tip over!

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Okay, well, I get all that. I have the probe right against the jar (actually a 2L beaker) inside a bucket with a ferm wrap, water level at the height of the tea in the beaker. Johnson controller set at 74f. So the water being measured is the water at the wall of the beaker.

My question was just whether there is a significant rise in temp within the KT during fermentation. Since it's nowhere near as vigorous as beer, I'm assuming there won't be an appreciable differential between the brew and the bucket. I just wanted to be sure.

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My bad. No there is not a significant rise in temperature.

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Thanks!

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