Robust Construction: Industrial-grade bi-metal disc designed for high-cycle reliability in residential and commercial heating applications

Its Single Pole Single Throw (SPST) configuration ensures a clean

it has likely failed and requires replacement

protecting technicians from the blower assembly and electrical hazards

Safe Operation: Includes a built-in internal pressure interrupter to disconnect the circuit in the event of an electrical fault

McDonnell & Miller 324500 O-Ring Robust Construction: Industrial-grade bi-metal discMaintain precise system pressure and eliminate leak paths with the McDonnell & Miller 324500 Tetraseal O Ring. This pack of five high performance seals is the engineered replacement for the discontinued 324435 part number, ensuring a direct fit without the need for field modifications. Designed as a critical boiler control replacement part, these o rings are specifically optimized for low water cut off (LWCO) and mechanical water feeder assemblies.