Xylem-McDonnell & Miller 51-S-2-HD Head Mechanism 136200 51-S-2

The Xylem-McDonnell & Miller 51-S-2-HD 51-S-2 Head Mech. 136200 looks to be a replacement component for McDonnell & Miller 51-S-2 controls. These controls are commonly employed in hydronic heating systems, such as boilers. The Xylem-McDonnell & Miller 51-S-2-HD head mechanism most likely contains crucial components for sensing water levels and operating the burner accordingly. While I cannot go into detail about its function without additional information, its design enables quick and easy replacement without disturbing piping, potentially reducing downtime for repairs. If you can provide more information regarding the model 51-S-2 controls or the HVAC equipment you're working with, I might be able give you a more particular description.