McDonnell & Miller 51-2-HD Control Freon the internal snap disc has

the internal snap disc has failed and the replacement limit switch is required

The minimum position (MinPos) potentiometer allows contractors to set a fixed minimum opening for the damper

Note that single pole pressure controls with manual reset have a fixed differential

for maximum service life and to prevent sediment buildup

McDonnell & Miller 51-2-HD Control Freon the internal snap disc hasThe McDonnell & Miller 51 2 HD is a heavy duty head mechanism only (Part Number 135100) designed specifically for field replacement on Series 51 2 mechanical water feeders. This unit is engineered for low pressure steam and hot water boiler applications, supporting systems with a maximum vessel pressure of 35 PSI. As a specialized low water cut off (LWCO) component, it features a snap acting SPDT switch that provides simultaneous feed control and