OEM Lennox Hot Surface Ignitor — 98P77

The genuine OEM Lennox 98P77 hot surface ignitor (HSI) lights the gas burners in your Lennox furnace on every heating cycle. Energized by the furnace control board when the thermostat calls for heat, the element glows to ignition temperature and lights the fuel as the gas valve opens. Because it fires on every cycle, the HSI is one of the hardest-working and most commonly replaced parts in a gas furnace.

Common failure symptoms: No heat despite the blower running, a furnace that clicks but never lights, ignition lockout after multiple failed attempts, or an ignitor element that stays dark and cold. The silicon carbide or silicon nitride element is fragile and prone to cracking from age, thermal stress, or handling.

Why OEM matters: The OEM Lennox 98P77 matches the precise electrical resistance, warm-up profile, and bracket geometry required by your Lennox control system. Generic replacements risk incorrect timing, poor fit, and early failure. Choosing the genuine part ensures fast, reliable ignition and full compatibility with your equipment.