Configuring a new thermostat

Hi all,

I bought and installed a Dixell XR02CX thermostat.
manual: http://www.weissinstruments.com/dixell/pdf/XR02CX.pdf

should I calibrate it before using?

First probe calibration: (-9.9÷9.9°C) allows to adjust possible offset of the first probe.

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how do I do this? standard thermometers are never completely accurate. Or did I misunderstand this?

a second question:

Differential: (0,1°C ÷ 25°C) Intervention differential for set point. Compressor Cut IN is SET
POINT + differential (Hy). Compressor Cut OUT is when the temperature reaches the set point.

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as I understand, if I want to ferment at 20°C and my "Differential" is 2°C
then the temp will move between 22°C and 20°C (in practice probably even 23°C-19°C due to probe sensitivity). Is this what it means ?

so what would be a good setting for the Diff ?
what temp swings still allow for healthy fermentation?

I'm not familiar with that particular controller, but generally you should not need to calibrate the probes supplied with the unit. I would check them and only adjust the offset if need be. The two degree C differential should be fine. The beer temps won't swing anywhere near that much and will likely vary less than one degree. I have no idea what the optimum differential would be. It will always be a compromise and my best guess would be to keep the fermenting wort temperature swings to +/- one degree C and that should be easy to do. The large volume of wort or beer will only change temperature very slowly due to it's large thermal mass. The air in the fermentation chamber will see much larger temperature swings, but not the beer itself.

(I had to edit this and change the suggestions as I realized that you were working with centigrade, not Fahrenheit)