As an auxiliary flame sensor

terminal G must be connected to an additional reference electrode that is as long as the lowest sensing probe to ensure a complete electrical path

Using it on normally open hardware may result in improper plunger seating or coil burnout

It is also compatible with 750mV heating systems

Emerson Alco 030623 Solenoid Valve 320734-701 As an auxiliary flame sensorThe Emerson Alco 030623 Solenoid Valve, technically designated as model 210CA 1 2 B 5 8P, is a 2 way normally closed pilot operated assembly engineered for high demand industrial steam and hot water applications. Designed with a rugged brass body and specialized ethylene propylene (EPDM) elastomers, this valve provides a reliable seal for hot water systems up to 210F at 100 PSI and low pressure steam systems at 15 PSI. The pilot operated mechanism