McDonnell & Miller 751P-MT-120 GuardDog Electronic Manual Reset Low Water Cutoff – 120V

Condition: New, Open Box

The McDonnell & Miller 751P-MT-120 GuardDog is a manual reset low water cutoff designed for commercial and industrial hot water and steam boilers. It serves as a primary or secondary control for hot water systems and as a secondary safety control for steam boilers. This model meets ASME Standard CSD-1 requirements, ensuring that if a low water condition occurs during a power loss, the control will remain in lockout mode until manually reset.

The unit features an LED power indicator (green) and a low water LED indicator (red) for quick diagnostics. The test switch allows system verification, and the 20,000-ohm sensitivity probe ensures precise water level detection. It operates at 120V and has high electrical load ratings, making it suitable for heavy-duty applications.

Note: The PA-800 probe is not included in this listing. Only the items shown in the pictures are included.

Features:

• Manual Reset: Required to restore operation after a low water event
• Application: Compatible with hot water and steam boilers
• ASME Standard CSD-1 Compliant: Ensures safety in low water conditions
• LED Indicators:
  • Green LED: Power status
  • Red LED: Low water warning
• Test Switch: Allows easy testing of system functionality
• 20,000 Ohm Sensitivity Probe: Provides accurate low water detection
• Voltage: 120V operation

Electrical Ratings:

• At 120V: 7.2A (AFL), 43.2A (ALR)
• At 240V: 3.75A (AFL), 21.6A (ALR)

Environmental Ratings:

• Max Ambient Temperature: 120°F

Applications:

This low water cutoff is ideal for use in:

• Commercial & Industrial Hot Water Boilers (Primary or Secondary Control)
• Steam Boilers (Secondary Control Only)
• Process Heating Systems Requiring Low Water Protection

Comparable Products:

If the McDonnell & Miller 751P-MT-120 is unavailable, consider:

• McDonnell & Miller 750-MT-120 (Electronic, Manual Reset, 120V, Similar Features)
• Hydrolevel 1100 (Electronic Low Water Cutoff for Boilers, 120V, Auto Reset)
• McDonnell & Miller 63M (Mechanical, Manual Reset, Low Water Cutoff, 120V)

Related:

• McDonnell & Miller GuardDog 751P-MT-120 low water cutoff
• 120V electronic low water cutoff for boilers
• ASME CSD-1 compliant manual reset low water control
• Steam boiler safety cutoff switch McDonnell & Miller
• Hot water boiler low water protection device

Questions:

1. How to reset a McDonnell & Miller 751P-MT-120 low water cutoff?
2. What are the ASME CSD-1 requirements for boiler low water cutoffs?
3. How does the manual reset function work on the GuardDog 751P-MT-120?
4. What probe is compatible with the McDonnell & Miller 751P-MT-120?
5. Where to buy a replacement 120V electronic low water cutoff for boilers?

Disclaimer:

McDonnell & Miller is a registered trademark of Xylem Inc. This product description is provided for informational purposes and is not affiliated with or endorsed by McDonnell & Miller or Xylem Inc. Always verify compatibility before purchase.

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