McDonnell & Miller 157S Controller R-410A Designed with a 1/2-inch crank

Designed with a 1/2-inch crank arm

Key Benefits for Contractors: Precision Sampling: Optimized straight-tube design minimizes air turbulence for highly accurate static pressure readings

Proven Reliability: Features a liquid-filled sensing element for consistent accuracy across the aquastat controller lifecycle

Upgrade and maintain system integrity with the York S1-331-03009-000 Control

21-27 bracket gasket

McDonnell & Miller 157S Controller R-410A Designed with a 1/2-inch crankThe McDonnell & Miller 157S is a heavy duty combination low water cut off and pump controller engineered for commercial and industrial steam and hot water boilers. This specific OEM part #173502 features the 157S series head mechanism (part #173003) equipped with a snap acting SPDT switch. Designed for high pressure applications up to 150 psi (10. 5 kg cm), this controller ensures precise liquid level management, acting as a critical failsafe by