What is the method for checking flame sensor current when the igniter also serves as the sensor?

The method for checking the flame sensor current when the igniter also serves as the sensor involves measuring the current flow through the circuit that indicates the presence of a flame. When the igniter also functions as a flame sensor, the current that flows through it signifies that the flame is successfully established.

Installing a DC millivolt meter in series with the ground wire to the module is an effective way to assess the operational status of the flame sensor. This method allows for measuring the voltage drop across the sensor as current flows through it when there is a flame. By doing this, you can determine whether sufficient flame presence is being detected, which is critical for the safe operation of gas appliances.

Other methods, such as directly attaching a multimeter to the igniter, may not provide an accurate measurement of the flame sensing capability, as it could interfere with the operation of the igniter. Similarly, measuring the resistance of the igniter does not provide real-time data on its functioning during operation and cannot confirm if the flame is being detected effectively. Hence, measuring current flow through the ground wire to the module provides the necessary insight into the performance of the flame sensor.