Temperature control and yeast management are pretty important. A thermometer can tell you temp but won't control the temp for you.
Want to make a hef? Ferment at 75 and you'll get banana. Ferment at 63 get clove. Ferment at 68 and you get balance.
You want one and they're bitchin. I currently use Johnson a19 to control freezer ambient temp at 53 for porter secondary. and Johnson a419 temp controller with the thermowell and a brew belt to keep my wheat at 68 in the same freezer. House temp is 69 to 75 and I don't want too much banana in my wheat. (Both controllers are available at Midwest brew supply).
I started with the mechanical one then added the digital with thermowells. Between the temp controlled freezer, a brew belt, the thermowell and the a419 I have nice flexibility for my small space.
Simply sticking a mechanical probe in my wheat would not work for this.
On my a419 I wired it myself and can plug 3 things into it. They will all operate around the same set point so during sub fermentation winter temps I can do triple batches if similar beers. Put the thermowell in one of the batches, set all 3 brews close together so they are in the same ambient temp condition.
