I'm just curious as to how the micro breweries control the temperature of the fermentation with large fermentation. Do the FV have temp control built in or what.
Because of their thermal mass and the exothermic nature of fermentation only cooling is needed. as said a chiller unit pumping chilled liquid into a SS coil in the fermenter.
Forum member Uncle Pumble at Cheshire brew house has one big chiller unit running constantly and each fermentor has an ATC800 controller which controls a solenoid valve so when coolant is needed the vavle is opened allowing coolant into the SS coil and shut off when the right temp is reached.
Just brewed a 4 barrel batch and saw the temperature dip down below 17c towards the end of the fermentation so just put a little fan heater pointing at the bottom of the FV to keep the temperature up. Seems to work :)