Furnace Igniter — part that lights gas burners at home

A furnace igniter is a burner-lighting component that ignites gas at the burners in a modern gas furnace during startup.

Furnace Igniter diagram — labeled parts, dimensions, and installation context

What It Is

A furnace igniter is the part that lights the gas burners in a modern gas furnace. Most residential systems use a hot surface igniter that glows red-hot, while some older systems use spark ignition.

Types

Common types include silicon carbide hot surface igniters, silicon nitride igniters, and spark ignition electrodes. The replacement must match the furnace design and mounting arrangement.

Where It Is Used

Furnace igniters are used in gas furnaces and some other gas-fired heating appliances. They work with the control board, pressure switch, gas valve, and flame sensor.

How to Identify One

The igniter sits near the burners and is usually visible after the burner compartment cover is removed. If the furnace starts its draft cycle but never lights, a cracked or non-glowing igniter is a common suspect.

Replacement

Replace the igniter when it is cracked, electrically open, contaminated, or no longer heats enough to light the burners reliably. Because igniters are fragile, handling matters.

Furnace Igniter — FAQ

What does a furnace igniter do?

It ignites gas at the burners in a modern gas furnace during startup. In a home, that helps the surrounding system work the way it should.

How can I tell if a furnace igniter needs attention?

The inducer may run without burner ignition, the furnace may lock out after several attempts, or the house blower may come on with no heat. A visibly cracked igniter is a very common failure sign.

Can I replace a furnace igniter myself?

Some homeowners replace igniters successfully because the part is accessible and usually held by a few screws. The job still requires shutting off power and confirming the right replacement part.

How much does furnace igniter repair or replacement cost?

Igniters are often one of the more affordable furnace parts to replace. Total service cost rises if the real problem is the control board, gas valve, pressure switch, or flame-sensing circuit.