McDonnell & Miller RS-1-LP-S Sensor

The McDonnell & Miller RS-1-LP-S (Part Number 176218) is a heavy-duty, single-level low pressure remote sensor probe designed specifically for hydronic heating and low-pressure steam applications. Built for precision in liquid level control, this sensor features a 3/4" NPT tank connection and a fixed 2-9/16" short probe, making it ideal for tight clearance installations where a standard probe would be impractical. Engineered to interface with Series 750 or PCH/PCL control units, it provides a reliable low water cut-off signal to protect boiler internals. The unit is rated for a maximum steam pressure of 15 psi and a water pressure up to 160 psi, withstanding process temperatures up to 250°F. Its NEMA 1 general-purpose enclosure ensures protection for the electrical terminations while allowing for straightforward vertical or horizontal mounting. For contractors, the RS-1-LP-S offers a "set and forget" solution for monitoring critical fluid levels in commercial and residential systems without the need for constant maintenance or blow-down procedures.

• Compact Short Probe Design: The 2-9/16" probe length allows for installation in narrow manifolds or headers without grounding out against the pipe wall.
• High Temperature Tolerance: Rated for 250°F, ensuring performance stability in demanding hydronic and low-pressure steam environments.
• Versatile Mounting: Unlike many displacement-style sensors, this probe can be installed in either a vertical or horizontal orientation to suit existing piping.
• Minimal Maintenance: The probe technology requires no blow-down, significantly reducing labor costs and system downtime compared to float-type controls.
• Standardized Threading: The 3/4" NPT connection provides a secure, leak-proof fit with standard boiler tappings and equalizing piping.

Is the probe included with the RS-1-LP-S or sold separately?
The 176218 model is a complete assembly that includes the integrated short probe, unlike the standard RS-1-LP which often requires separate probe selection.

Can this sensor be used in high-pressure steam boilers?
No, this unit is specifically rated for low-pressure systems with a 15 psi limit for steam. For high-pressure applications up to 250 psi, the RS-1-BR-1 series is required.

What is the minimum clearance required for the probe?
To prevent false signals or electrical shorts, ensure a minimum of 1/4" clearance between the probe and any metal grounding surface within the tank or pipe.

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.