Inducer motor for starters. This blows hot gasses outside. Circuit boards need power, the switches and relays on the boards. There’s programming and timings that are on the boards. Most models now also have wifi modules too.
Wut? No. None of that.
Programming for what? What switches and relays? You have no idea what you’re on about. 🤦
Are you talking tank, or tankless. Tankless gas all of that
Tank can easily have none except solenoid in valve
Goddamn you’re an idiot. Were your parents more inbred than the Habsburgs?