The McDonnell & Miller 157S-RL (Part Number 176902) is a heavy-duty combination low water cut-off and pump controller designed explicitly for steam boilers with an integral water column

ensuring the valve remains leak-proof against high differential pressures common in large-scale commercial piping loops

or obstructed return ductwork rather than a faulty switch

this valve is strictly engineered for R-22 refrigerant

This switch is compatible with a wide range of Amana

Lochinvar & A.O. Smith 100271886 Probe 326058-756 The McDonnell & Miller 157S-RLThe Lochinvar & A. O. Smith 100271886 Probe is a critical lower temperature probe designed for precise thermal monitoring in high efficiency commercial gas water heaters. Engineered with an integrated connector, this replacement water heater sensor ensures seamless communication between the storage tank and the unit's control board. It is specifically compatible with Lochinvar Cyclone and A. O. Smith BTH 300A, 400A, and 500A models. As a veteran grade