What condition must be met to consider an HSI functioning properly?

To determine whether a Hot Surface Igniter (HSI) is functioning properly, the condition regarding the resistance matching the specifications is critical. The resistance of the HSI is a key indicator of its operational health. Each HSI model has specific resistance values that are considered ideal for it to function correctly. When the resistance is within these specifications, it ensures that the HSI can draw the appropriate amount of electrical current needed to heat up and eventually ignite the gas.

Moreover, if the resistance is out of specifications, it may suggest that the igniter is defective, potentially leading to insufficient heating and failed ignition of the burner. Therefore, checking the resistance against the manufacturer specifications is a reliable diagnostic step to verify the HSI's functionality.

While it is beneficial for the surface of the HSI to glow, this is not a definitive measure of proper function by itself since glowing may occur without the HSI effectively igniting fuel. Similarly, airflow is important for overall system efficiency but does not directly relate to the functional evaluation of the HSI itself.