The furnace ignitor is a critical component that lights the burner and keeps a home warm. Resetting an ignitor can resolve common issues like a failed ignition or intermittent heating, but it requires careful steps to avoid damage or safety hazards. This guide explains when to reset, step-by-step procedures, safety precautions, troubleshooting tips, and when to call a professional.
| Issue | Quick Action | When To Call Pro |
|---|---|---|
| No heat, clicking sound | Reset power and check ignitor visually | If ignitor is cracked or repeatedly fails |
| Intermittent heat | Inspect connections and restart furnace | If issue recurs after resets |
| No clicking, no ignition | Check power, thermostat, and control board | If control board or gas valve suspected |
How A Furnace Ignitor Works
A furnace ignitor replaces the traditional pilot light and uses a heated element—either hot surface ignition (HSI) or intermittent spark—to ignite the burner. HSIs glow red-hot to light gas, while spark ignitors produce a spark. Both types are controlled by the furnace’s control board and safety sensors. Understanding the type helps diagnose failures and choose the correct reset and replacement procedures.
Safety Precautions Before Resetting The Ignitor
Working on a furnace involves risks including electrical shock, gas leaks, and fire. Before any reset attempt, turn off power at the switch and the breaker, and shut off gas if indicated by the manufacturer. Wear safety gloves and eye protection, avoid metal tools near the ignitor, and follow manufacturer instructions. If odor of gas is present, evacuate and call the gas utility or emergency services.
Tools And Materials Needed
Gather basic tools: a multimeter for electrical checks, a screwdriver or nut driver set for access panels, a flashlight, a soft brush or compressed air for cleaning, and a replacement ignitor if necessary. A camera or phone can document wiring positions before disconnecting. Using the correct replacement part number is essential to avoid damage.
Pre-Reset Checklist
- Verify thermostat is set to heat and above room temperature.
- Confirm furnace switch and breaker are on.
- Inspect air filter and replace if dirty.
- Listen for blower or inducer motor operation and any unusual noises.
- Look for error codes on the furnace control board LED and consult the manual.
Steps To Reset A Furnace Ignitor Safely
1. Power Down The Furnace
Turn off the thermostat, flip the furnace power switch to the off position, and switch off the circuit breaker serving the furnace. Waiting at least 60 seconds ensures capacitors discharge and the control board resets electrically.
2. Access The Ignitor
Remove the furnace access panel(s) using the appropriate screwdriver or nut driver. Locate the ignitor near the burners; HSIs are ceramic rods or plates, while spark ignitors are small electrode assemblies. Avoid touching the ignitor surface directly if possible.
3. Inspect And Clean
Visually inspect the ignitor for cracks, chips, or signs of burning. Clean nearby dust and debris with a soft brush or compressed air. For HSIs, do not sandpaper or use solvents—fragile ceramic elements can break easily.
4. Check Electrical Connections
Ensure wiring to the ignitor and ground connections are secure and not frayed. Document wire locations before disconnecting. Use a multimeter to check continuity per manufacturer specifications if comfortable doing so.
5. Restore Power And Attempt Restart
Reinstall access panels temporarily, restore breaker and furnace power, and set the thermostat to call for heat. Observe ignition sequence: inducer motor, pressure switch, ignitor warm-up or spark, and burner ignition. Many modern furnaces will attempt ignition automatically after a reset.
6. Manual Reset If Furnace Has A Reset Button
Some furnaces include a reset or “limit” switch accessible on the blower housing. Only press a reset button once; waiting 30 minutes between attempts prevents overheating damage. Refer to the owner manual for location and specific instructions.
Diagnosing Common Outcomes After Reset
If the furnace ignites and runs normally, monitor for a full heating cycle to confirm stability. If ignition fails, note any error codes, clicking sounds, continuous attempts to ignite, or complete silence. These observations guide the next diagnostic steps.
Troubleshooting: Why Resetting May Fail
- Cracked Or Burned Ignitor: Visible damage requires replacement—reset won’t help.
- Weak Electrical Supply: A tripped breaker, loose wiring, or voltage drop can prevent proper ignition.
- Faulty Flame Sensor: The sensor may shut down burners immediately after ignition if dirty or failing.
- Gas Supply Issues: Closed valves, empty gas connection, or a failing gas valve can stop ignition.
- Control Board Malfunction: If the board fails to cycle the ignitor or interpret signals, professional diagnosis is needed.
How To Test The Ignitor With A Multimeter
With power off, disconnect the ignitor and set a multimeter to measure resistance (ohms). For HSI ignitors, typical resistance ranges between 40 and 120 ohms but varies by model; consult the spec sheet. Spark ignitors will show high resistance and are usually tested by observing spark operation. If resistance is infinite or outside recommended range, replace the ignitor.
Replacing A Furnace Ignitor
If inspection or multimeter testing indicates failure, replace the ignitor. Order the correct OEM part using the furnace model number. Replacement steps generally include removing the old ignitor assembly, installing the new element carefully, reconnecting wiring, and testing ignition. Handle the new ignitor by its mounting bracket, not the ceramic element.
Maintenance Tips To Prevent Ignitor Failures
- Replace disposable air filters every 1–3 months to reduce dust and airflow strain.
- Schedule annual HVAC maintenance to inspect the ignitor, flame sensor, and burners.
- Keep the furnace area clean and free of clutter to avoid dust buildup.
- Ensure proper ventilation and carbon monoxide detectors are installed and functioning.
When To Call A Professional
Contact a licensed HVAC technician if the ignitor is cracked, if repeated resets don’t fix the problem, or if gas valve and control board issues are suspected. Professionals perform safe gas handling, complex electrical diagnostics, and parts replacement with warranty considerations.
Costs And Time Estimates
Typical ignitor replacement parts cost between $30 and $150 depending on the furnace make and type. Labor costs for a technician can range from $100 to $300, depending on service fees and travel. A DIY replacement may take 30–60 minutes for a competent homeowner; professional service appointments usually last 1–2 hours.
Common Myths And Risks
Myth: Repeatedly pressing reset is harmless. Fact: Multiple resets can mask underlying issues and cause component stress. Myth: Ignitors can be cleaned with sandpaper. Fact: Abrasive cleaning damages ceramic elements. Risk: Working without shutting off gas or power can cause fire or electrocution.
Key Indicators That Resetting Helped
- Stable Ignition: The burner lights on the first attempt and remains lit for the full cycle.
- No Error Codes: Control board LED returns to normal status.
- Consistent Heating: Room temperatures match thermostat settings after a cycle.
Frequently Asked Questions
How Often Do Ignitors Fail?
Ignitor lifespan varies by usage, but many last 3–10 years. Frequent cycling, dirt, or electrical issues can shorten life. Regular maintenance extends lifespan.
Can A Homeowner Replace An Ignitor?
A homeowner with basic mechanical skills can replace many ignitors safely if power and gas are off and the correct part is used. However, if unsure, hiring an HVAC pro is recommended for safety and warranty preservation.
Why Does The Furnace Click But Not Ignite?
Clicking may indicate the control board is attempting ignition but the ignitor isn’t heating or sparking. Causes include a failed ignitor, weak electrical supply, or a blocked gas flow.
Will Resetting Fix Intermittent Issues?
Resetting can clear electronic faults, but intermittent problems often indicate a failing component or wiring issue. If problems recur after a reset, further diagnosis or replacement is required.
Additional Resources And Manufacturer References
Consult the furnace owner’s manual for model-specific instructions and error codes. Reliable resources include manufacturer websites, the U.S. Consumer Product Safety Commission for safety recalls, and EPA guidance on indoor air quality. For gas leaks or safety emergencies, contact local utility services or 911.
Final Tip: Document any resets, repairs, or part numbers to help technicians diagnose recurring issues and to maintain a clear service history for the furnace.