The three-way valve does not switch to the sanitary circuit

If the boiler set temperature exceeds the value set by the parameter Th21 = 72 °C (Sanitary Thermostat 2), the three-way valve does not switch to the sanitary circuit for safety reasons.

To allow the proper operation of the three-way valve, it is necessary to reduce the boiler set temperature below the threshold set by the parameter Th21.