What igniter fits my Lennox furnace?

The correct replacement for Lennox model OEM Lennox Ignitor & Flame Sensor Assembly — 79J21 is this exact part. It is the factory-specified replacement with exact OEM specifications. Using a part with different specifications can cause equipment damage or void your warranty. You can verify this by checking the data plate on your Lennox equipment which lists the model number OEM Lennox Ignitor & Flame Sensor Assembly — 79J21.

My furnace will not ignite. What part is bad?

A furnace that will not ignite after the draft inducer runs typically has a failed igniter. The hot surface igniter should glow bright orange within 60 seconds. If it does not glow at all, it is cracked or burned out. If it glows weakly, it is degrading and should be replaced preventively. Average lifespan: 3 to 7 years.

Lennox

OEM Lennox Ignitor & Flame Sensor Assembly — 79J21

Name: OEM Lennox Ignitor & Flame Sensor Assembly — 79J21
Brand: Lennox
SKU: LNX-79J21
Price: 29.95 USD
Availability: InStock

SKU: LNX-79J21 Brand: Lennox

$29.95 $39.95

OEM Guaranteed

Same-Day Ship

30-Day Returns

Secure Checkout

Texas CMBL #19328542014

SAM.gov Registered

Govt POs Accepted

The genuine OEM Lennox 79J21 combines the hot surface ignitor and flame sensor into a single factory assembly. The ignitor heats up to light the gas burners on a call for heat, while the integrated flame sensor confirms the flame using rectification so the control board can safely keep the gas valve open. It is manufactured to the precise resistance, mounting, and gap specifications required by compatible Lennox furnaces.

When this assembly fails, you may experience symptoms such as no ignition and no heat, a cracked or glowing-but-not-lighting ignitor, repeated ignition lockouts, burners lighting and immediately shutting down, or a control board fault indicating ignition or flame-sense failure. Hot surface ignitors are fragile and degrade over time with each heating cycle.

OEM matters because the 79J21 delivers the correct ignitor resistance and flame-rod signal characteristics that your Lennox control board expects. Aftermarket substitutes can draw the wrong current, crack prematurely, or produce unstable flame readings that cause nuisance lockouts. The factory assembly restores reliable, safe ignition and consistent furnace operation.

Shipping Information

Orders placed before 3PM CST ship same business day
Standard delivery: 2-5 business days
Express shipping available at checkout
Free shipping on orders over $75
Tracking number emailed upon shipment

Return Policy

30-day returns on unused parts in original packaging
Electrical parts (capacitors, contactors, control boards) are final sale once installed
Email info@nationalhvacparts.com to initiate a return
Refunds processed within 5-7 business days

OEM Lennox Ignitor & Flame Senso...

$29.95

Frequently Asked Questions

Does this Igniter fit my Lennox OEM Lennox Ignitor & Flame Sensor Assembly — 79J21?

Yes. This is the factory-specified OEM igniter for the Lennox OEM Lennox Ignitor & Flame Sensor Assembly — 79J21. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.

How do I replace the igniter on my Lennox OEM Lennox Ignitor & Flame Sensor Assembly — 79J21?

Difficulty: Medium (20–30 min)
Step 1: Turn off power and gas. Step 2: Open furnace panel. Step 3: Locate igniter near burners. Step 4: Disconnect two-wire plug. Step 5: Remove mounting screw. Step 6: Install new igniter — do NOT touch element with fingers. Step 7: Reconnect, close panel, restore power/gas.

My furnace won’t ignite. What part is bad?

Furnace won’t ignite after the draft inducer runs = failed igniter. The hot surface igniter should glow bright orange within 60 seconds. No glow = cracked/burned out. Weak glow = degrading. Average lifespan: 3–7 years. Replacement: $15–$40 DIY.

Is this igniter compatible with Bryant or Payne too?

Many Lennox parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.

Should I use OEM or aftermarket for my Lennox igniter?

OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.

How fast does National HVAC Parts ship?

Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.

Menu

OEM Lennox Ignitor & Flame Sensor Assembly — 79J21

Shipping Information

Return Policy

Frequently Asked Questions