Originally Posted by jason91notch
We have heard great feedback from customers simply adding a few bottles of warm water to raise temperatures instead of ice. Also if left sealed during active fermentation the heat given off will slightly raise temperatures.
Homebrewers have reported success using a fermwrap heater, thermowell stopper and a temperature controller to dial in exact temps they want in very cold environments.
We just caution the use of a heating element as our fermentation cooler's upper material limits are 115 degrees F and our fermentation cooler was not specifically developed to be used in conjunction with a heating element.
Hope this helps!