Furnace Ignitor Guide: Hot Surface vs Silicon Nitride for Minnesota Homeowners

Furnace Ignitor Guide: Hot Surface vs. Silicon Nitride — Minnesota Homeowners

The ignitor is the spark plug of your furnace—it lights the gas burner every heating cycle. When it fails, your furnace won't light. Understanding ignitor types helps you diagnose problems faster and know when replacement is coming.

How Modern Furnace Ignitors Work

Modern furnaces use electronic ignition rather than standing pilot lights. When the thermostat calls for heat, the control board sends power to the ignitor, which heats to 1,800–2,000°F within seconds, then ignites the gas burner. The whole sequence takes about 30–60 seconds.

Hot Surface Ignitor (HSI) — Silicon Carbide

The most common ignitor type in furnaces from the 1990s–2000s. Silicon carbide ignitors glow orange when working correctly. They're fragile—touching them with bare hands deposits skin oils that cause premature failure. Lifespan: 3–7 years typically. Cost to replace: $50–$150 including labor.

Silicon Nitride Ignitors — The Modern Standard

Goodman and other modern furnaces use silicon nitride ignitors, which are significantly more durable than silicon carbide. They withstand more thermal cycling, handle moisture better, and typically last 7–10+ years. All new Goodman furnaces from Furnace Direct include silicon nitride ignitors.

Signs Your Ignitor Is Failing

Furnace starts then shuts off quickly (no ignition). No glowing element visible during startup. Furnace runs blower but no heat. See our diagnosis guide, ignition guide, and emergency guide.