McDonnell & Miller 51S-2-HD Replacement HeadMcDonnell & Miller 51S 2 HD is a replacement head with cutoff designed for the 51S boiler line. This OEM grade component fits 136200 assemblies, delivering precise shutdown and reliable safety for your boiler system. Engineered for dependable performance, the 51S 2 HD replaces worn or failed heads quickly, minimizing downtime and extending the life of your boiler. Whether you are performing routine maintenance or a field repair, this replacement head

enhancing overall system longevity and reducing operational costs

By restoring proper housing alignment

close-on-rise switch with Therm-O-Disc components

Suitable for commercial and industrial applications

supporting consistent mounting spacing and sensor performance across varied ductwork configurations

The high-reliability design achieves a Cv of 5 with power ratings of 10

while the universal power input (102–260 VAC

The device also features a Lo-open point at 165 ± 6 psig and a Lo-close function

Set point ranges from -30 to 90°F

The Erie Controls AT13A00T Valve Actuator is a reliable electric actuator designed for heating and cooling systems

the ICM325A maintains stable head pressure

Industrial Water Control