What terminals should measure 24 volts if the pilot has been proven?

When the pilot has been proven in a heating system, the terminals that should measure 24 volts are the ones responsible for confirming that the ignition sequence is complete and that the system is prepared to engage the main burners. In this case, the terminals designated as 4 and C are typically connected to the secondary circuit of the transformer, ready to supply power for the operation of the gas valve or burner system once the ignition process is verified.

The configuration is designed to ensure that if the pilot light is successfully ignited and stable, the system provides the necessary voltage to activate the main components that require power to operate safely. This measurement is crucial in confirming that the system is functioning correctly and that there is power where it is needed to heat effectively.

While other terminals may exist for various functions within the system, they would not be active in this scenario of having a proven pilot light. Therefore, recognizing that terminals 4 and C are the correct ones that indicate a successful ignition and activation of the heating elements is fundamental to understanding the diagnostics of gas and oil heating systems.