McDonnell & Miller 51-2-HD Control 30067439-890 while the wide operating temperature

while the wide operating temperature range of -30°F to 140°F ensures dependable performance in unconditioned mechanical spaces

Its robust NEMA 1 enclosure protects the snap-acting switch mechanism

allowing for a thermostat-free flow control setup that simplifies field installations

Precision Performance: Maintains a ±

McDonnell & Miller 51-2-HD Control 30067439-890 while the wide operating temperatureThe 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