Hydrolevel 650P Low Water Cut Off for Hot Water Boilers with Test Button & Light 120V

Hydrolevel low water cut-offs are electrically operated. A probe is installed in the boiler shell or external manifold and is connected to the control unit. Water is used as a conductor to complete the circuit between the probe and the boiler shell. When water is in contact with the probe, the circuit is completed; when the water level drops below the probe, the circuit opens. Hydrolevel controls provide contacts to de-energize the burner circuit in a low water condition. 

The 650P interrupts power immediately in a low water condition. Burner circuit locks-out if water remains below probe for 30 seconds. Manual reset will not trip due to power failures. Test button checks burner circuit to ensure proper control operation without lowering the water level.