Fermentation chamber question

[car421]

I converted a 12cf to a fermentation chamber using a Johnson A419 controller. I was wondering if I need to offset the temp of the controller to get a proper temp in my carboy. I am using a 6 gal glass carboy.

 

[MonsterBrew]

Not sure of exactly what you mean... But when using a temperature controller, there is two main points to consider.

1. Keeping the temperature difference wide, this helps keep the controller from cycling the compressor too much. So if you want 68F, then you should probably set it so it ranges from 66 to 70.
2. During high fermentation activity, the temperature of the wort and the air can be off by as much as 5 - 8 degrees F. So consider setting the temperature lower than what you actually want to ferment at.

 

[microbusbrewery]

Attach the probe to your fermenter so that you're reading the temp of the fermenter and not the ambient air temp. It's also a good idea to sandwich the probe between your fermenter and some kind of insulation (e.g. a scrap piece of rigid foam insulation).