McDonnell & Miller 51-2 Low Water Cutoff with Automatic Feeder and #2 Switch

The McDonnell & Miller 51-2 is a combination low water cutoff (LWCO) and automatic water feeder designed to protect steam and hot water boilers from dangerous low water conditions. This dual-function safety control automatically monitors boiler water level and adds makeup water when needed, while immediately shutting down the burner if water drops to an unsafe level.

Key Features:

• Integrated low water cutoff and automatic feeder in one compact unit
• Includes #2 switch configuration for 135,000 BTU boiler capacity
• Float-operated mechanism provides reliable water level detection
• Automatic makeup water feed maintains proper boiler water level
• Manual reset safety lockout prevents burner restart until water level is restored
• Durable construction designed for long service life in demanding applications
• Standard 1/2" NPT mounting connection

This control combines essential boiler safety and maintenance functions in a single device, reducing installation complexity and providing dual protection against low water damage. The automatic feeder maintains optimal water levels during normal operation, while the low water cutoff provides critical safety shutdown capability. Ideal for residential and light commercial steam and hot water boiler systems.