McDonnell & Miller 354140 Replacement Probe 30067439-890 Ensure the flow arrow on

Ensure the flow arrow on the housing points toward the expansion device during installation

Engineered specifically as a 2-position spring return motor

especially if mineral scale or heat stress has caused the original polymer to degrade

This furnace high limit switch replaces multiple legacy part numbers

Direct OEM Compatibility: Serves as the official successor to 624721 and 621957

McDonnell & Miller 354140 Replacement Probe 30067439-890 Ensure the flow arrow onThe McDonnell & Miller 354140 is a high precision PA 800 RX2 replacement probe engineered for field service reliability in low water cut off (LWCO) applications. Designed specifically for the PS 800 series and PS 850 series controls, this probe features a 1 2" NPT male threaded connection and a remote mount configuration for versatile installation in steam or hot water boilers. Built to withstand demanding boiler environments, it maintains high signal