McDonnell & Miller FPC-1000-U Control

The McDonnell & Miller FPC-1000-U (MPN 144706) is a universal, field-configurable electronic low water cut-off (LWCO) designed to replace nearly all probe-type controls in the field, including the PSE-802-U-24 and 752P-MT-U-24. This Boilerwize series control is engineered for both steam and hot water applications, featuring an extended barrel probe with a 3/4" NPT connection for deeper tapping penetration. Its patented conductivity-based sensing technology distinguishes between actual low water conditions and water volatility, significantly reducing nuisance shutdowns while providing dry fire protection. The unit is power-flexible, allowing for 24V or 120V operation, and can be configured for automatic or manual reset to meet ASME CSD-1 requirements.

Technical Superiority for Contractors: This control consolidates 19 legacy models into one SKU, simplifying truck stock. It features a self-cleaning probe designed to minimize scale buildup, extending maintenance intervals to five years. The integrated tri-function button allows for a push-to-test diagnostic without draining the boiler, ensuring the burner circuit interrupts as intended. With brass-threaded metal-to-metal seals and high-visibility multi-function LEDs (Green for Auto, Yellow for Manual, Red for Low Water), the FPC-1000-U provides clear status indication and a leak-free mechanical installation for residential or commercial hydronic systems.

Key Benefits for the Jobsite

• Universal Field Configuration: One control handles 24V/120V systems and auto/manual reset, acting as a direct cross for the McDonnell & Miller PSE-800 and 750 series.
• Patented Self-Cleaning Probe: Proprietary technology reduces mineral encrustation on the electrode, ensuring consistent conductivity readings and reducing the need for annual probe pulling.
• System Testing Without Draining: The tri-function test button verifies burner circuit operation and safety logic without requiring a physical water level drop.
• Robust Environmental Ratings: Supports maximum water pressures up to 160 psi and steam pressures up to 15 psi, with a 250°F maximum water temperature rating.
• Streamlined Installation: Features wrench flats and easy-access wiring knock-outs within a NEMA 1 enclosure to speed up replacement time.

Common Questions & Contractor Tips

Can this replace a float-style LWCO?
Yes, the FPC-1000-U can serve as a primary or secondary LWCO replacement for older float-style units, provided there is a suitable 3/4" NPT tapping available. It is often preferred for its lack of moving parts which can seize due to sediment.

How do I switch between 24V and 120V?
The voltage is field-selectable via internal jumpers. Always verify your supply voltage before powering the unit to prevent damage to the PCB. Note that the switch rating is 7.5 FLA at 120 VAC.

What does the blinking red LED mean?
A solid red LED indicates a low water condition. If the LEDs are blinking alternately during startup, the unit is in default mode and requires configuration using the test button to lock in your system settings (Steam/Water and Reset mode).

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.