It is a double-pole

including the plunger assembly and return spring

Leaks typically occur due to mineral or calcium buildup within the valve seat or a degraded internal gasket

ensuring the integrated circuit board maintains gas flow only when ignition is confirmed

Lennox 19L57 Pressure Switch 30067439-890 It is a double-poleThe Lennox 19L57 Pressure Switch is a critical OEM safety component engineered for precise airflow monitoring in residential and commercial furnaces. This . 25" WC pressure switch is designed to verify that the draft inducer motor is creating sufficient negative pressure to vent combustion gases safely before allowing the ignition sequence to proceed. As an SPST (Single Pole Single Throw) configuration, it provides a reliable normally open circuit