If the flame rectification circuit is operating normally, how much current should flow through the flame sensor?

The flame rectification circuit is a critical component in many heating systems, particularly in gas furnaces. It serves to confirm the presence of a flame and is essential for safe and efficient operation. When the system is functioning correctly, the flame sensor generates a very small amount of current as it detects the flame's presence.

Typically, the current flowing through the flame sensor in a properly operating flame rectification circuit is in the range of microamps. This low level of current is due to the fact that the circuit operates on the principle of utilizing the ionization produced by the flame itself. Rather than needing a higher current to function, the flame sensor effectively utilizes the ionized gas to create a small electrical current that can be measured. This ensures that only a flame is capable of completing the circuit, thus enhancing safety.

Higher levels of current, such as milliamps or amps, would indicate that the system may be experiencing issues, as standard gas flames do not produce enough ionization to support such levels of current flow. Consequently, the presence of a flame shown by a current flow in the microamp range is an indication of normal operation in the flame rectification circuit.