and MC-4311 series

The switch should read as "closed

This gasket is the primary valve seal for Series 53

Seamless Integration: Compact form factor and standard mounting allow for rapid installation in existing electrical control boxes or panels

including popular ALP

Armstrong Furnace R43127-001 Flame Sensor and MC-4311 seriesThe Armstrong Furnace R43127 001 Flame Sensor is a critical OEM replacement part designed for precision flame rectification in residential heating systems. This furnace flame sensor acts as a primary safety component, communicating directly with the integrated furnace control board to confirm burner ignition. If the sensor fails to detect the required microamp signal within the ignition trial period, the system triggers a safety lockout to prevent the