McDonnell & Miller 94-7B-HD Controller Refrigerant Built with a NEMA 48

Built with a NEMA 48 frame size

this OEM heating element ensures proper oil viscosity and prevents the accumulation of liquid refrigerant in the sump during off-cycles

Broad Series Integration: Validated for use across major residential lines

Voltage drop usually occurs due to high resistance in the wiring or a failing thermopile generator

McDonnell & Miller 94-7B-HD Controller Refrigerant Built with a NEMA 48The McDonnell & Miller 94 7B HD is a high performance head mechanism only designed for heavy duty commercial and industrial steam applications. As a critical replacement head mechanism for Series 94 and 194 controllers, this unit integrates a combination low water cut off and pump controller to maintain precise boiler water level control. Engineered for systems with a maximum pressure of 250 PSI, it utilizes a 7B potentiometer switch to provide a 135