A low liquid level sensor in a hot water heating system permitting testing operability thereof in situ without draining down the system. The sensor is located in a cavity that has an opening in the bottom thereof in fluid communication with the liquid in the vessel during normal operation of the system. The end of the opening is at a lower elevation than the sensor and liquid from the vessel is in the cavity during normal operation of the system. When the liquid drops to a predetermined low level the sensor activates the safety cut-off. Valved passed mea...
In a pressurized heating system having water in a boiler and a low water level sensor and safety cut-off device associated with the boiler and operable to shut off the system when the water in the boiler drops below a predetermined level, said low water sensor device comprising: (a) a housing having a cavity; (b) means mounting said housing on the vessel such that a substantial portion of said housing, having the cavity therein, is external of the vessel; (c) a sensor in said cavity responsive to the liquid level therein and operably associated with the ...
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