Impact of "in range" temperature fluctuation during primary fermentation

[Hannabrew]

I don't have a fermentation chamber but I do use a combination of swamp cooling with fan as well as immersing the fermenter in a tub of water with the frozen bottle rotation (aka the poor man's fermentation chamber). All my fermenters have thermowells and I'm using inkbird controllers as my thermometer.

I usually use the tub of water to chill to my pitching temp as my IC only gets me so far in the summer. Sometimes I get antsy and pitch a bit higher than my target temp but keep cooling to get to where I want to be. Once I've hit that target I try to keep it there with the rotating frozen bottles but it can be challenging.

For example, I brewed a kolsch and a NEIPA yesterday.

I cooled the kolsch down to 62 and pitched w029 while continuing to chill to my target of 60. By the time fermentation activity started I was at 60 and kept it within 1F for about 12-18 hours. Over the course of one night it jumped from 61 all the way up to 67...I immediately added the full arsenal of frozen bottles to bring it back down to 60ish within a couple hours.

With the NEIPA I chilled down to 69 and pitched 1318 and continued chilling down to my target temp of 64F. I kept it between 64 and 66 for about 24 hours but that same night the temp jumped up to 71. Again I did what I needed to do to get it back down to 64F within a couple hours.

My questions are

1) how much does the initial pitch temp matter vs the temp it reaches an hour or so after pitch?

2) while I haven't gone out of the recommended range for the respective yeasts, I'm concerned about what the repercussions are of temperature fluctuations during primary fermentation (especially early on).

 

[dhop]

I've read that as long as the initial pitch temp is in the allotted range of the yeast you should be fine. So there shouldn't be a huge difference if you pitch at 62, and hope to ferment actively at 60. From personal experience, I've pitched above the stated range, perhaps around 75F, and then cooled down to 65F in my chamber. While there may have been subtle esters from the yeast, the beer was just fine.

I think fast wild swings are not great for the yeast, but I imagine the temperature swing is gradual so there shouldn't be a huge issue (your beer isn't ruined).

On a side note, perhaps these warm ups are due to fermentation beginning? The actively fermenting wort will raise its temperature a few degrees and could cause these spikes as opposed to just a warmer room temp. You could prevent this by keeping more bottles of ice in the water during the first few days of fermentation.

 

[Hannabrew]

It's definitely heat from fermentation, the room is at 70 consistently. I'm not worried about ruining my beer as I've had plenty of batches that have fermented like this and have been great. I guess I'm just asking from more of a scientific point of view, what are the potential risks of doing temperature control the way I'm doing it as opposed to set it and forget it?