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

If the microamp signal remains low after cleaning

for maximum service life and to prevent sediment buildup

Optimized Performance: Maintains the internal pressure required for efficient fuel-to-air ratios and peak boiler efficiency

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

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