Hydrolevel CycleGard CG450 Steam Boiler Low Water Cut-Off 120 VAC 20 Min ILT Standard EL1214 3/4" NPT Probe Hydrolevel's CycleGard Low Water Cut-Offs are used as the primary low water cut-off on residential and light commercial steam heating boilers. They are also used in certain low pressure steam process applications. Hydrolevel controls utilize a non-moving heavy duty electronic probe to sense liquid levels. The probe can be installed in an equalizing line or directly into a boiler or tank. When water is in contact with the probe it completes a circuit between the stainless steel probe tip and the tank or boiler surface in which the probe is installed. When the water level drops below the probe the circuit opens. Hydrolevel low water cut-offs for hydronic or steam systems use the water signal to allow the burner to operate. If the water level drops below the probe the circuit opens and the control shuts of the burner.[]