A hot surface igniter is a ceramic element, usually silicon carbide or silicon nitride, that glows red-hot when energized and lights the gas at a furnace's burners. It replaced the standing pilot light on most modern gas furnaces, saving gas between cycles. Igniters are brittle and wear out over thousands of heating cycles.
Why it matters to you
In a heating-dominated climate like the Lower Mainland's, igniters see heavy use for much of the year, and a failed igniter means no heat at all. A furnace that clicks and runs its inducer fan but never lights is a classic igniter symptom.
Practical guidance
Never touch the igniter element — skin oils and a light knock can crack it. If your furnace tries to start but never lights, turn it off at the service switch and book a technician rather than cycling it repeatedly.