The McDonnell & Miller 157S-A (Part Number 173702) is a combination low water cut-off and pump controller engineered for reliable protection and automatic water level management on steam boilers. Featuring a snap-acting SPDT (Single-Pole Double-Throw) switch and alternate tappings, this unit offers flexible installation options to suit a wide range of boiler configurations.
Product Overview
The 157S-A combines two critical boiler safety and control functions into a single, compact device. As a low water cut-off, it monitors boiler water level and shuts down the burner if the water drops to an unsafe level, preventing costly boiler damage and potential hazards. As a pump controller, it automatically activates the feed pump to maintain the proper operating water level, ensuring consistent and efficient boiler operation.
Key Features
- Combination low water cut-off and pump controller in one unit
- Snap-acting SPDT switch for reliable, precise switching action
- Alternate tappings for versatile installation and piping flexibility
- Float-operated mechanism for accurate water level sensing
- Designed for use on steam heating boilers
- Durable cast iron body construction for long service life
- Part Number: 173702
Applications
- Residential and light commercial steam boilers
- Hot water heating systems requiring low water protection
- Boiler systems requiring automatic pump feed control
Why Choose the McDonnell & Miller 157S-A?
McDonnell & Miller, a brand under Xylem, has been a trusted name in boiler controls and hydronic system components for decades. The 157S-A delivers dependable low water protection and pump control in a single device, reducing installation complexity and providing peace of mind that your boiler is protected against low water conditions. The snap-acting SPDT switch ensures positive, chatter-free switching, while the alternate tappings give installers the flexibility needed to accommodate various piping configurations.
