What is the proper method of testing flame rectification?

The proper method of testing flame rectification involves measuring the DC microamps produced by the flame sensor when it is exposed to the combustion flame. When the flame is present, it creates a rectifying effect due to the ionization of the gases in the flame, allowing a small amount of current to flow. By placing the meter in series with the flame sensor, you can accurately measure this DC microamp current flow, which is essential for confirming that the flame is present and that the sensor is functioning correctly.

This microamp measurement is critical because it indicates whether the flame sensor is detecting the flame as intended. A flame sensor typically requires a certain minimum current to operate effectively; therefore, accurate measurement is crucial for troubleshooting and ensuring safe and efficient operation of the gas furnace. When the meter is set up in this manner, it allows for direct observation of the flame sensor's response to the flame, providing valuable insight into its performance.

Other methods, such as using a voltage meter in parallel or an ammeter that is improperly connected, would not yield the correct information needed to assess the operation of the flame sensing system, and measuring flame temperature would not provide the electrical information required to verify flame rectification.