Description
The Xylem-McDonnell & Miller 150S-M-MD is a heavy-duty combination low water cut-off and pump controller engineered for reliable protection of steam and hot water boilers in commercial and industrial hydronic systems. Featuring a snap-acting manual reset SPDT switch with Maximum Differential (MD) operation, this unit provides precise water level control and boiler safety in a single, compact device.
Product Overview
The 150S-M-MD combines two critical boiler protection functions — low water cut-off and pump control — into one robust unit, reducing installation complexity and cost. The snap-acting SPDT (Single Pole Double Throw) switch ensures fast, positive switching action, while the manual reset feature requires deliberate operator intervention before the boiler can restart after a low water condition, adding an important layer of safety. The Maximum Differential (MD) designation provides the widest possible operating differential between pump-on and pump-off water levels, making it ideal for applications where water level fluctuates significantly.
Key Features
- Combination low water cut-off and pump controller in a single unit
- Snap-acting SPDT switch for fast, reliable switching response
- Manual reset operation — requires intentional reset after low water trip
- Maximum Differential (MD) operation for wide water level control range
- Designed for steam and hot water boiler applications
- Compact, integrated design simplifies installation and reduces component count
- Part Number: 172802
How It Works
The 150S-M-MD uses a float mechanism to continuously monitor boiler water level. When water drops to the low water cut-off threshold, the snap-acting SPDT switch opens the burner circuit, shutting down the boiler to prevent damage from dry firing. Simultaneously, the pump controller function manages the feedwater pump to maintain proper water level. The Maximum Differential setting allows the pump to operate over a broader water level range before switching, reducing short-cycling and extending equipment life.
Applications
- Commercial and industrial steam boilers
- Hot water heating boilers
- Hydronic heating systems requiring low water protection
- Systems requiring combined pump control and low water cut-off functionality
Why Choose McDonnell & Miller
McDonnell & Miller, a brand of Xylem, has been a trusted name in boiler controls and hydronic system protection for over a century. The 150S series is a proven platform widely specified by engineers and relied upon by boiler technicians across North America for dependable, long-service boiler protection.
Reviews
There are no reviews yet.