Head Mechanisms

McDonnell & Miller model number 42S-HD is a head mechanism for model number 42-S controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller model number 64-HD is a head mechanism for model number 64 and 764 controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller model number 93-HD is a head mechanism, with standard number 5 switch, for model number 93 and 193 controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller model number 93-7B-HD is a head mechanism, with standard number 7B switch, for model number 93 and 193 controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller 162402 model 93-HDLS head mechanism less switch for low water cut-offs and pump controllers used on steam boilers. Learn More

McDonnell & Miller model number 94-HD is a head mechanism, with standard number 5 switch, for model number 94 and 194 controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller model number 94-HDLS is a head mechanism, without standard number 5 switch, for model number 94 and 194 controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller model number 94-7B-HD is a head mechanism, with standard number 7B switch, for model number 94 and 194 controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller 173003 model 150S-HD replacement head mechanism with snap-action switch assembly repairs Series 150S and Series 157S low water cut-off pump controllers for steam boilers. Learn More

McDonnell & Miller 172809 model 150S-M-HD replacement head mechanism with snap-action switch assembly with manual reset repairs Series 150S-M and Series 157S-M low water cut-off pump controllers for steam boilers. Learn More

173103 McDonnell & Miller model 150S-MD-HD head mechanism with maximum differential operation for Series 150S and Series 157S low water cut-offs with the maximum differential function. Learn More

McDonnell & Miller 172810 model 150S-M-MD-HD replacement head mechanism with the maximum differential operation and manual reset switch for Series 150S and Series 157S boiler controls. Learn More

McDonnell & Miller model number 159S-HD is a head mechanism for model number 159S controls. Head mechanisms include everything except a float chamber. They allow for quick and easy replacement by removing the bolts on the float chamber and then removing and replacing the new unit, with no need to disrupt piping. Learn More

McDonnell & Miller replacement head mechanism with manual reset for Model 94-M combination low water cut-off/pump controllers. Learn More

McDonnell & Miller combination low water cut off and pump controller head mechanism with two snap-acting manual reset and SPDT switch for steam boilers with 150 psi max pressure. Learn More

McDonnell & Miller model number 64M-HD is a head mechanism for use with model E-11M-24V (SKU: MI1615) or model E-11M-120V (SKU: MI1616) reset switches. Learn More