Every brewing system - be it a mashtun, BIAB device or fermeter - is different. To perfectly hit the set target temperature it is therefore possibly and necessary to adjust the temperature controller settings to your device.
Usually, a automatic calibration will do this for you. Read how it works here: Calibration.
In some rarer cases, you might want to change the parameters yourself. You can do this for Relais and PWM capable switches separately. This section will explain the reasoning behind it.
The following parameters are available:
: If 1, the relais will turned of when the target temperature is reached. If the relais will be turned of earlier.
: Controls the influence of the temperature change rate. The higher the bigger.
: Controls the influence of the integrated temperature change. The higher the bigger.
: The hystersis is a dead zone around the target temperature, in which the relais will not be turned on again. It is symmetrical and covers both positive an negative deviations. This means, that if the hystersis is set to 0.2°C and the target temperature is 60°C (140°F) the deadzone will span from 59.9°C to 60.1°C.