McDonnell & Miller 354081 Replacement Probe

The McDonnell & Miller 354081 Replacement Probe is a critical component for maintaining secondary low water cut-off (LWCO) functionality in commercial and residential boiler systems. This 3/4" NPT probe serves as the sensing element for Series PS-800, PS-850, and PA-800 remote probe controllers. Engineered for high-pressure environments, this stainless steel probe detects water levels via conductivity, ensuring the burner circuit is interrupted if a low-water condition occurs. As an OEM McDonnell & Miller replacement part, it is compatible with the 750, 750-MT-120, PS-801, and PS-851 models. Field technicians often prioritize this low water cut-off probe for its reliable signal transmission and resistance to scale buildup. When troubleshooting a boiler probe sensor that has failed due to fouling or electrical breakdown, installing this genuine McDonnell & Miller 354081 unit restores system integrity without the compatibility risks associated with aftermarket alternatives.

Technical Benefits for Contractors

• Direct 3/4" NPT Threading: Facilitates a standard mechanical seal into the boiler tapping or equalizing line.
• Broad Series Compatibility: Engineered specifically for McDonnell & Miller PS-800 and PS-850 systems, including high-pressure and remote sensing configurations.
• Conductivity Sensing Accuracy: Optimized for precise liquid level detection, reducing false trips and dry-fire risks.
• Rugged Material Construction: Designed to withstand high-temperature hydronic environments and chemical water treatments.

Common Questions

Is the 354081 probe compatible with the model 750 controller?
Yes, this probe is the specified replacement for the 750 series, as well as the PS-800 and PS-850 families of low water cut-offs.

Does this probe include the housing or just the sensor?
The 354081 is the replacement sensor probe only. It is designed to be threaded into existing 3/4" NPT ports on the boiler or remote sensor manifold.

Can I use this for both steam and hot water applications?
This probe is suitable for use in various hydronic applications where the controller (like the PS-800) is rated for the specific medium, typically found in hot water heating boilers.

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.