Different Size Batches, Same Ferm Chamber

[str1p3s]

Hello all,
I plan on brewing a porter recipe in two different sizes on the same day. First, I'll brew a 3 gallon batch and then a 5 gallon batch later that day. I am going to experiment with cocoa nibs in the smaller batch.

My question is, can I put them both in the same fermentation chamber? Which one should I attach the probe to? I'm afraid if I attach the probe to the larger one, the chamber will get too cold for the smaller one and stall the fermentation. And conversely, the larger one might get too warm if I attach the probe to the smaller one. Anyone with experience at trying this? Any other ideas?

 

[jwalk4]

This may come as too late, but my advise is to RDWAHAHB.

If you want, you could tape the probe to the big carboy, and adjust your temp setting to be a degree or two warmer. But mostly, I wouldn't worry my head over it.

 

[mattdee1]

Early on, I did a 7 gallon split batch of Centennial Blonde with a 5 gal bucket, and the 2 gal LBK from a Mr. Beer kit.

I had the STC-1000 probe attached to the bucket during fermentation. The finished beer from the bucket was great, the beer from the small fermentor was decent, but notably inferior. It had some weird ester-y flavors to it, which, in retrospect, I assume were caused by the wide temperature swings the small fermentor would have seen while sitting in a temperature environment that was being controlled to hold a much larger thermal mass at a certain temperature. Am I 100% certain that this was the cause of the weird flavors? No, but everything else was the same between the two beers (including the yeast, Nottingham) so it sure makes sense.

Again, this was a blonde ale... maybe a darker beer would be more forgiving.

 

[SGTSparty]

Given @mattdee1 's experience I'd attach your probe the the smaller vessel and then set your temp control to the low end of the range for that yeast. What yeast are you using? if the range is 60-70 for example then set it to 62 on the smaller vessel, odds are the larger vessel will be a bit higher and take longer to get down to fermentation temp but then it should swing less than the smaller one and should ride pretty smoothly once its down to temp and hopefully stay below the top end of the range. Or put it on the larger one and put the smaller vessel in a water bath to try and make up for the lack of thermal mass?