Description
The Xylem McDonnell & Miller 150S is a combination low water cut-off and pump controller designed to protect steam and hot water boilers from the hazards of low water conditions. Featuring a snap-acting SPDT (Single-Pole Double-Throw) switch, the 150S simultaneously monitors water level and controls the feed pump, making it a reliable two-in-one solution for residential and light commercial boiler systems.
How It Works
The 150S uses a float-operated mechanism to continuously sense boiler water level. When the water drops below the safe operating level, the snap-acting SPDT switch triggers an immediate burner shut-off to prevent dry-firing and costly boiler damage. At the same time, the pump control circuit activates the feed pump to restore water to the proper level, then shuts it off once the correct level is reached — providing fully automatic, hands-free boiler protection.
Key Features
- Combination low water cut-off and pump controller in a single unit
- Snap-acting SPDT switch for reliable, positive switching action
- Float-operated water level sensing mechanism
- Automatic burner shut-off on low water condition
- Integrated pump control to automatically restore safe water levels
- Suitable for steam and hot water boiler applications
- Designed for residential and light commercial boiler systems
- McDonnell & Miller quality — a trusted name in boiler protection for over 100 years
Product Specifications
- Part Number: 171702
- Model: 150S
- Switch Type: Snap-Acting SPDT (Single-Pole Double-Throw)
- Control Type: Combination Low Water Cut-Off and Pump Controller
- Brand: Xylem – McDonnell & Miller
Application
The McDonnell & Miller 150S is ideal for use on steam boilers and hot water heating systems where both burner protection and automatic water feed control are required. It simplifies installation by combining two essential boiler safety and control functions into one compact, side-mounted unit — reducing parts count and labor time on the job.
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