This Navien Printed Circuit Board (PCB) is a primary component designed for the NFB-C series of Navien boilers. The PCB serves as the control center for the boiler, managing and coordinating all its functions. It is equipped with a main board designation (B/D), indicating it's the central hub for electrical inputs and outputs within the system. The specific model, GBC301, is designed to be compatible with NFB-C series boilers, ensuring seamless integration and optimal performance. This PCB is responsible for interpreting signals from various sensors in the boiler, then sending appropriate commands to different components to maintain desired temperature levels and safe operation.