Flow switch. Water differential pressure switch.
This warning appears with the opening of the contact relating to the flow switch or to the differential pressure switch. This alarm is not detected in the first 40 seconds from when the pump is switched on. The machine goes into lockout when the maximum number of flow switch interventions allowed is exceeded. If frost protection mode (and therefore the pump too) is activated in standby, the flow switch status is also controlled. FL/PD.