McDonnell & Miller 752P-MT-24 Control

The McDonnell & Miller 752P-MT-24 is a professional-grade electronic manual reset low water cut-off engineered specifically for technical requirements in commercial and industrial boiler applications. Operating on 24Vac control voltage, this unit serves as a critical primary or secondary limit control for hot water heating systems and a secondary safety control for steam boilers. As an ASME CSD-1 compliant device, the 176296 model ensures that if a low water condition occurs during a power interruption, the system remains locked out upon power restoration, necessitating a manual intervention to resume firing. This probe-type LWCO features a 20,000-ohm sensitivity and includes a 3/4-inch NPT standard probe for direct immersion. Integrated LED diagnostics provide immediate field status; the green LED indicates "Power On," while the red LED alerts the technician to a "Low Water" condition. A dedicated test switch allows for routine functional verification without draining the system, simplifying maintenance for HVACR contractors and facility engineers.

• CSD-1 Compliance: Meets strict ASME safety codes for manual reset functionality on pressure vessels.
• Dual Application Versatility: Compatible with both hot water and steam boiler configurations.
• Advanced Diagnostics: Green and red LED indicators allow for rapid troubleshooting of power and water levels.
• Integrated Test Switch: Enables code-required testing of the internal relay and probe circuit without manual blowdown.
• Memory Logic: Retains lockout status through power cycles to prevent unsafe automatic boiler restarts.

Common Questions

How do I reset the control after a low water event?
Once the water level is restored above the standard probe, you must physically depress the manual reset button. The LEDs will flash during the reset cycle before the burner circuit is re-energized.

Can this be used on a steam boiler?
Yes, the 752P-MT-24 is frequently utilized as a secondary low water cut-off on steam systems to meet CSD-1 manual reset requirements, though it is typically the primary control for hot water boilers.

What is the maximum pressure rating for this unit?
The probe assembly is rated for a maximum steam pressure of 15 psi and a maximum water pressure of 160 psi at temperatures up to 250°F.

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.