Doing so can lead to heat exchanger fatigue

providing a reliable failsafe against overheating

If the millivolt output drops below the required threshold

including 17D

This "E" series spring is specifically dimensioned for the 325-5 and 325-5A regulators

Armstrong Furnace R44992-001 Sensor Ignitor Doing so can lead toThe Armstrong Furnace R44992 001 Sensor Ignitor is a critical OEM replacement component designed for high efficiency gas furnaces. This dual purpose assembly functions as both a hot surface igniter and a flame sensor, ensuring precise ignition sequences and reliable flame rectification. Engineered for high temperature durability, the R44992 001 provides the resistance required for consistent heating cycles while maintaining the millivolt signal