The CH return water temperature sensor error
CH return sensor out of normal operating range (short circuit or open circuit). If sensor goes outside the range, error will be generated. In case sensor is back to the normal operating range, error is gone. In error mode, heat demands will be disabled. In case 2 or more sensors are broken, controller will pick up the first that was outside the operating range. Resolving situation can be achieved only if the sensor is within operating range again.
