The McDonnell & Miller 1575 Controller (Part Number 171907) is a professional-grade combination low water cut-off and pump controller designed specifically for commercial and industrial steam boiler systems. This electronic control unit features a robust cast iron probe chamber with three pre-installed stainless steel probes, engineered to provide precise water level management up to a maximum pressure of 250 psi and temperatures of 406°F. The 1575 series utilizes solid-state technology and redundant circuitry to ensure fail-safe performance, protecting the burner from dry-firing while simultaneously managing boiler feed pump cycles. With 1" NPT connections and 1 HP rated relays for both burner and pump circuits, this unit excels in demanding mechanical rooms where reliability is non-negotiable. It includes a 60-second burner-off time delay to prevent nuisance shutdowns caused by surging or priming, and the probe sensitivity is optimized at 60,000 ohms for conductance-based level sensing. Key Benefits Dual-Function Reliability: Integrates primary low water fuel cut-off and pump control into a single, high-pressure rated assembly. Advanced Diagnostics: Features internal and external LEDs for real-time status monitoring, including high ambient temperature alerts and probe sequence validation. Flexible Installation: The remote electronic control unit can be mounted away from the probe chamber in a NEMA 1 enclosure, while the chamber itself is NEMA 4X rated. Field Customization: Probes can be cut to set specific pump differentials, and a 4th probe can be added for high-water alarm capabilities. Safety Redundancy: Equipped with an automatic reset and a manual test button to verify burner circuit interruption instantly. Common Questions How do I prevent nuisance burner shutdowns on this controller? Adjust the field-selectable burner-off time delay (up to 60 seconds) to compensate for turbulent water levels and momentary fluctuations common in high-load steam systems. Can the McDonnell & Miller 171907 be used for high-pressure applications? Yes, this model is specifically rated for 250 psi maximum steam pressure, making it suitable for high-pressure industrial process boilers and commercial heating plants. What should I check if the burner fails to turn off during low water? Inspect the stainless steel probes for scale buildup or rust, as fouling can bridge the gap and provide a false signal. Ensure the wiring at the 1 HP burner relay terminals is secure and follows the manufacturer's diagram. This item is not eligible for free shipping. 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.
