I purchased a Johnson Controls a few months ago and use it in a Mini-Fridge to create a temperature controlled fermentation chamber. It works incredibly well at controlling temperature, and my beer quality has drastically improved.
I've done about 10 beers using the controller in my Fermentation chamber, and I've kept track of (among other information) three temperatures: 1) the temperature that I set the dial/knob at; 2) the ambient temperature of the fermentation chamber; and 3) the temperature reading on the fermometer (i.e., best guess at beer temp.).
Naturally, during fermentation, the degrees can be drastically different. I may have the dial set on 48, creating an ambient temp of 55, with a fermentation temperature of 60~62. Obviously during any fermentation the fermentation temperature will be greater than ambient. After fermentation completes, I will have raised the dial to ~54, creating an ambient of ~61, and the beer will be 60~62. As the beer stops fermenting, it goes back to the ambient temp. This all makes sense.
However, it it appears that the actual ambient temperature of the fermentation chamber is about 7~8 degrees greater than the reading on the dial.
To remedy this, I believe I must re-calibrate the Johnson Controls unit.
Could anyone with experience with the Johnson Controls Analog A19 unit tell me how I re-calibrate it so that the temperature I set on the dial will be equal (or at least closer) to the actual ambient temperature?