Description
Xylem-McDonnell & Miller 157S Combination Low Water Cut-Off and Pump Controller
The Xylem-McDonnell & Miller 157S is a combination low water cut-off and pump controller designed to protect steam and hot water boilers from the damaging effects of low water conditions. Featuring a snap-acting SPDT (Single-Pole Double-Throw) switch mechanism, the 157S provides reliable, precise switching action for both burner cut-off and pump control functions in a single, compact unit. This combination design simplifies installation and reduces the number of individual controls required on the boiler, saving time and labor costs.
Key Features
- Combination low water cut-off and pump controller in one unit
- Snap-acting SPDT switch for reliable, precise switching performance
- Protects boilers from low water conditions that can cause serious damage or failure
- Simplifies installation by combining two functions into a single control
- Float-operated mechanism for accurate water level sensing
- Durable construction built to withstand demanding boiler room environments
- Part Number: 173502
How It Works
The 157S uses a float-operated sensing mechanism to continuously monitor the water level in the boiler. When the water level drops below the safe operating threshold, the snap-acting SPDT switch activates to cut off the burner, preventing the boiler from firing under unsafe low water conditions. Simultaneously, the pump controller function can be used to manage the feed pump, automatically restoring water to the proper level. This dual-function design ensures comprehensive boiler protection and efficient water level management.
Applications
- Steam boilers in residential, commercial, and light industrial settings
- Hot water boilers requiring low water protection
- Systems requiring combined burner cut-off and pump control
- Replacement or upgrade for existing low water cut-off controls
Why Choose the McDonnell & Miller 157S
McDonnell & Miller, a trusted Xylem brand, has been a leading manufacturer of boiler controls and low water cut-offs for decades. The 157S continues that tradition of quality and reliability, offering HVAC professionals and building engineers a dependable solution for boiler safety and water level management. Its combination design reduces installation complexity, while the snap-acting SPDT switch ensures consistent, long-lasting performance cycle after cycle.
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