Loading cycle of a boiler with one level probe: The loading function regulates and controls the correct level of water in the boiler.

If the level probe in not covered by water, then the pump and solenoid valve output are simultaneously activated. When   the probe is reached by water, the pump and solenoid valve outputs are deactivated and remain switched off until the status of the probe changes again. In addiction there is a safety probe, when it is not covered by water, the activation of the outputs is not allowed.