Lennox 79J21 Ignitor

The Lennox 79J21 Ignitor is a heavy-duty, genuine OEM electrode designed specifically for high-demand residential and commercial furnace applications. As a dual-purpose Lennox spark ignitor and flame sensor, this component provides the high-voltage arc necessary for rapid gas ignition while simultaneously monitoring the burner flame to ensure safe, continuous operation. This furnace ignitor replacement is built using a glazed L-5 steatite insulator and a nickel-plated steel male terminal to withstand the extreme thermal cycling common in modern high-efficiency units. Whether you are servicing a Lennox RTU or a compact rooftop package system, this 79J21 electrode ensures precise timing and reduces the risk of delayed ignition or lockout codes. Using an OEM Lennox part like the 79J21 is essential for maintaining the factory-specified combustion sequence and long-term reliability of the heating assembly in environments where downtime is not an option.

• Dual-Functionality: Operates as both a spark generator and a flame sensing rod, streamlining the combustion control process.
• OEM Precision: Engineered to the exact specifications of Lennox heating systems, ensuring perfect alignment within the burner rack.
• High-Temperature Durability: Features a high-grade ceramic insulator that resists cracking under intense heat and vibration.
• Corrosion Resistance: Nickel-plated terminals provide superior electrical conductivity and prevent oxidation in high-moisture environments.

How do I know if my Lennox 79J21 ignitor is bad?
Inspect the ceramic insulator for hairline cracks or a soot-covered tip. If the furnace attempts to light but fails to create a visible spark, or if it lights and immediately shuts down because the flame isn't sensed, this electrode is likely the culprit.

Is this a direct replacement for Lennox part number 79J2101?
Yes, the 79J21 is the current OEM designation and is fully backwards compatible with legacy part numbers 79H21, 79J2101, and PSE-L19.

Can I clean the tip of this electrode?
If the electrode is not cracked, you can lightly clean the metal probe with a fine-grit abrasive pad to remove carbon buildup, which often restores proper flame sensing signals to the control board.

This item is not eligible for free shipping.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.