Ideal part is located within the printed circuit board section. The printed circuit board or printed circuit board is the boilers central control. It monitors and controls every process that occurs via the sensors, switches and thermostats. It also enforces the safety protocols, making sure that the boiler ceases to function if any of the internal readings point to any kind of error or fault. The printed circuit board is essentially the brains of the appliance, ensuring everything is running correctly and safely.