Lochinvar & A.O. Smith 100074451 PCB 321894-708 provided the connection sizes match

provided the connection sizes match your suction line

it meets UL555 and UL555S requirements for smoke control

while the second switch is utilized to energize the boiler feed pump or a motorized feed valve as water levels fluctuate

this assembly includes the necessary baseplate to simplify installation for technicians

and VG9000 series globe valves

Lochinvar & A.O. Smith 100074451 PCB 321894-708 provided the connection sizes matchThe Lochinvar & A. O. Smith 100074451 PCB is a critical integrated control module designed for high efficiency commercial and residential water heaters and boilers. Known as the MC50 PCB, this genuine OEM component manages vital system operations including ignition sequences, temperature regulation, and safety circuit monitoring. Engineered for a precise fit in Lochinvar Knight and various A. O. Smith tankless models, it ensures absolute signal