This SPST pressure switch is factory-calibrated to a

As a safety limit switch

What causes these door switches to fail prematurely

ensuring clean switching and protecting sensitive HVAC control systems from premature failure during high-frequency operation

Williams 8909 Conversion Kit 324846-701 This SPST pressure switch isThe Williams 8909 is a field proven Natural Gas to Propane (LP) conversion kit specifically engineered for Monterey Plus Top Vent Furnaces. Designed for compatibility with the 50098 and 50096A series, this kit ensures a precise fuel conversion while maintaining the unit's 50,000 BTU rating. As a veteran grade OEM furnace part, the assembly includes the necessary main burner orifices and a dedicated pressure regulator for Williams brand gas valves.