Description
Xylem-McDonnell & Miller 150S-MD Combination Low Water Cut-Off and Pump Controller
The Xylem-McDonnell & Miller 150S-MD (Part Number 171802) is a combination low water cut-off and pump controller engineered for reliable boiler protection and pump management in hydronic and steam heating systems. Featuring a snap-acting SPDT (Single-Pole, Double-Throw) switch with Maximum Differential Operation, this control delivers precise, dependable response to low water conditions — helping prevent costly boiler damage and extending system service life.
Key Features
- Combination low water cut-off and pump controller in a single unit for simplified installation
- Snap-acting SPDT switch ensures fast, positive switching action for reliable boiler protection
- Maximum Differential Operation provides the widest possible differential between cut-off and pump-on points, reducing short cycling
- Designed for use on steam and hot water boilers in residential and light commercial applications
- Trusted McDonnell & Miller design backed by Xylem’s engineering expertise
- Part Number 171802 for easy cross-referencing and replacement ordering
Product Benefits
- Dual-function design reduces installation complexity and component count
- Protects boiler from low water damage by cutting off burner operation when water level drops below safe threshold
- Controls pump operation to maintain proper system water levels automatically
- Snap-acting switch mechanism minimizes arcing and extends electrical contact life
- Maximum differential setting helps stabilize water level cycling for more efficient system operation
Applications
- Steam boilers requiring low water cut-off protection
- Hot water boilers with pump control requirements
- Residential and light commercial hydronic heating systems
- Boiler replacement and retrofit installations
Product Details
- Brand: Xylem-McDonnell & Miller
- Model: 150S-MD
- Part Number: 171802
- Switch Type: Snap-Acting SPDT
- Operation Mode: Maximum Differential
