Originally Posted by deadguyry
I was not aware i needed a heat source i thought the point was that it would over ride the freezer and cause it to start heating up.
a freezer does not produce heat (other than as a byproduct of cooling). instead the controller will turn off the freezer - and if the outside ambient temp is below where you want your fermentation temp to be you are screwed.
A johnson controller does not automagically turn a device meant to keep things frozen into a device capable of heating.
there are two options on a single digital controller one for heat and one for cold - depending on which one you chose.
a dual stage can do both but must still be plugged into something capable of heating and a separate device capable of cooling.