McDonnell & Miller 354140 Replacement Probe

The 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 integrity and responsive sensing to prevent dry-fire conditions. Professionals typically specify this unit when replacing probes in PS-801-RX2-24 or PS-802-RX2-24 systems to ensure the safety of the pressure vessel. The stainless steel remote sensor probe provides liquid level control with a maximum water temperature rating of 250°F and an operating pressure limit of 160 PSI. For contractors, this drop-in replacement ensures the boiler safety device operates within factory specifications without modification.

• System Compatibility: Direct replacement for PA-800-RX2 probes used in PS-800 and PS-850 low water cut-off series.
• Robust Construction: Precision-machined 1/2" NPT threads and stainless steel probe rod for long-term corrosion resistance.
• Accurate Sensing: Specialized remote mount design provides responsive liquid level monitoring to protect the heat exchanger.
• Standard Fit: High-tolerance NPT connection ensures a leak-free seal in standard boiler tapping ports.

• Will this probe work with legacy PS-800 series controls? Yes, this PA-800-RX2 assembly is effectively the standard replacement for most PS-800 and PS-850 series units requiring a remote probe.
• Can I use this for high-pressure steam applications? This probe is rated for pressures up to 160 PSI and water temperatures up to 250°F; always verify your specific system operating ranges before installation.
• Is the sensing rod cuttable? It is generally recommended to use the factory length to maintain calibrated sensitivity; however, consult the McDonnell & Miller technical manual for site-specific modifications.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.