Furnace Ignitor Replacement Cost

What a Furnace Ignitor Does

The ignitor is responsible for lighting the gas burner at the start of each heating cycle. When the thermostat calls for heat, the furnace control board activates the ignitor, which heats up until it is hot enough to ignite the gas flowing from the burner. Once the flame is established and confirmed by the flame sensor, the ignitor's job is done until the next cycle.

Modern furnaces use one of two ignitor types. Hot surface ignitors (HSI) are the most common, consisting of a small silicon carbide or silicon nitride element that glows red-hot when electric current passes through it. The glowing element ignites the gas on contact. Direct spark ignition (DSI) systems use an electric spark to ignite the gas, similar to a gas stove lighter but more powerful.

Older furnaces (generally pre-1990) used a standing pilot light instead of an electronic ignitor. The pilot light burned continuously and ignited the main burner when the gas valve opened. Standing pilots have been largely replaced by electronic ignition because they waste gas by burning 24 hours a day, even when no heat is needed.

Why Ignitors Fail

Ignitors are consumable components that wear out through normal use. Each heating cycle subjects the ignitor to extreme temperature changes as it heats from room temperature to over 2,500 degrees Fahrenheit and then cools back down. These thermal cycles cause microscopic cracks in the ignitor element that gradually weaken it until it breaks.

Most hot surface ignitors last 3 to 7 years under normal use, though some last considerably longer. Furnaces in cold climates that cycle more frequently will wear out ignitors faster than furnaces in mild climates. Silicon nitride ignitors tend to last longer than the older silicon carbide type because they are more resistant to thermal shock.

Handling is another common cause of premature failure. The oils from human skin can create hot spots on a silicon carbide ignitor that cause it to crack during operation. HVAC technicians handle ignitors with gloves or a clean cloth for this reason. If an ignitor was recently replaced and failed again quickly, improper handling during installation may be the cause.

Voltage irregularities can also damage ignitors. Power surges, brownouts, or dirty power from aging household wiring can cause the ignitor to draw uneven current, accelerating wear. Homes with frequent electrical issues may experience shorter ignitor life.

Signs Your Ignitor Has Failed

The furnace does not produce heat. The thermostat calls for heat, the draft inducer motor starts, but the burner never lights. You may hear the normal startup sequence of fans and motors but no whoosh of the burner igniting. After several failed ignition attempts, the furnace locks out and the error light on the control board flashes a diagnostic code.

The furnace cycles on and off without heating. A weakening ignitor may occasionally fail to ignite the gas on the first attempt but succeed on a retry. This causes the furnace to go through partial startup cycles before finally producing heat, resulting in longer waits between the thermostat calling for heat and warm air actually reaching the registers.

A visible crack in the ignitor element. If you can safely access and visually inspect the ignitor (with the furnace power off), a visible crack or break in the ceramic element confirms the failure. A healthy ignitor appears as an intact, smooth element. A failed one may show a visible gap, fracture, or crumbling at the connection point.

Error codes on the control board. Most modern furnaces have a diagnostic LED on the control board that flashes a specific pattern when the ignitor fails or the flame is not detected after ignition attempts. Check your furnace's manual or the diagram typically printed inside the access panel to decode the flash pattern.

Professional Replacement vs DIY

Ignitor replacement is one of the few furnace repairs that some handy homeowners can perform themselves, though there are important caveats to consider before attempting it.

Professional replacement costs $150 to $400 during normal business hours. This includes the service call fee (typically $75 to $125), the diagnostic time to confirm the ignitor is the problem, the replacement part, and the labor to install it and verify the furnace operates properly. A professional also checks for other issues during the visit, such as a dirty flame sensor, clogged filter, or signs of heat exchanger problems, providing value beyond just the ignitor replacement.

DIY replacement costs $25 to $75 for the part and requires basic mechanical ability, a screwdriver, and the correct replacement ignitor for your furnace model. The process involves shutting off power to the furnace, removing the access panel, disconnecting the old ignitor's electrical connector, removing one or two mounting screws, installing the new ignitor without touching the element with bare skin, reconnecting the electrical plug, and restoring power. Universal ignitors are available at hardware stores for $25 to $40, while exact OEM replacements ordered by model number cost $30 to $75.

When to call a professional: If you are not comfortable working around gas appliances, if the furnace does not start after the ignitor replacement, or if you are unsure which part is the ignitor, call a licensed HVAC technician. Incorrectly diagnosing the problem and replacing the ignitor when the actual issue is a gas valve, control board, or flame sensor will not fix the furnace, and you will need a technician anyway. Also, some jurisdictions require a licensed professional to perform any work on gas appliances, even simple component swaps.

Ignitor Types and Compatibility

Silicon carbide ignitors are the older standard, found in furnaces manufactured from the 1990s through the early 2010s. They are flat or round black ceramic elements that glow orange-red when heated. Silicon carbide ignitors are more fragile and sensitive to handling oils, but they are widely available and inexpensive at $20 to $35.

Silicon nitride ignitors are the modern standard, found in most furnaces manufactured after 2010. They are typically white or gray and are more durable, more resistant to thermal shock, and less sensitive to handling than silicon carbide. They cost slightly more at $30 to $50 but last longer on average.

Universal ignitors are designed to fit multiple furnace models and are available at most hardware stores. They work well for most standard furnaces, though some high-end or proprietary furnace models require an exact OEM replacement to function correctly. When ordering, note the ignitor's voltage rating, mounting style (flat or round), and connector type to ensure compatibility with your furnace.

Reducing Emergency Costs

Ignitor failure during peak heating season often forces homeowners into expensive emergency service calls. After-hours service typically costs 50% to 100% more than daytime calls, turning a $200 repair into a $400 to $500 expense. Several strategies can help avoid this scenario.

Schedule a professional furnace tune-up each fall before the heating season begins. The technician will inspect the ignitor for signs of wear and recommend proactive replacement if it appears near the end of its life. Replacing a worn ignitor during a $100 to $150 maintenance visit costs far less than an emergency service call on a freezing weekend night.

Keep a spare ignitor on hand for your furnace model. The part costs $25 to $50 and lasts indefinitely in storage. If the ignitor fails on a cold night and you or someone in the household can perform the replacement, having the part available avoids the emergency service call entirely.