If a furnace with a hot surface igniter does not light, what should a technician check before replacing the igniter?

When a furnace with a hot surface igniter fails to light, checking the voltage to the igniter is a crucial step. The hot surface igniter requires a specific voltage to function properly; if it is not receiving adequate power, it will not heat up and ignite the gas. This check helps determine whether the issue is related to the electrical system rather than the igniter itself. If the igniter is not receiving the correct voltage, troubleshooting can focus on potential issues with the power supply, control board, or wiring.

When addressing issues with a furnace, evaluating voltage is often an initial diagnostic step as it can quickly identify whether the igniter is capable of performing its function. If the igniter is functioning correctly but still does not ignite, further investigation may be warranted into other parts of the ignition system or safety mechanisms that might be affecting operation.