Ignitor & Pilot Light Repair in Erie, Colorado
When your furnace won't light, the ignition system is usually the culprit. Modern furnaces use hot surface ignitors or electronic spark ignition, while older units have standing pilot lights. We diagnose and repair all types of furnace ignition systems.
Types of Furnace Ignition Systems
| Type | How It Works | Common In |
|---|---|---|
| Hot Surface Ignitor (HSI) | Electric element heats to 1800°F+ to ignite gas | Most furnaces since 1990 |
| Spark Ignition | Electric spark lights a pilot, pilot lights burners | Mid-efficiency furnaces, some newer units |
| Standing Pilot | Continuously burning flame lights burners | Furnaces built before 1990 |
Hot Surface Ignitor (HSI) Problems
Hot surface ignitors are the most common ignition system today. They glow orange-hot to ignite the gas.
- Furnace clicks/hums but doesn't ignite
- Ignitor glows but burners don't light
- Ignitor doesn't glow at all
- Furnace tries multiple times then locks out
- Visible crack in the ignitor element
Why Ignitors Fail
- Age: Average lifespan 3-7 years (silicon nitride last longer)
- Thermal cycling: Heating/cooling cycles cause stress cracks
- Contamination: Oil from fingers weakens the element (never touch!)
- Voltage spikes: Power surges can kill ignitors instantly
- Silicon Carbide ignitor (older, more fragile): $80-150 installed
- Silicon Nitride ignitor (newer, more durable): $100-200 installed
- Universal ignitors available for most furnaces
This is one of the most common furnace repairs — and one of the most affordable.
Flame Sensor Issues
The flame sensor is a safety device that detects whether the burners actually lit. If it doesn't sense flame, it shuts off the gas valve to prevent gas buildup.
- Burners light, then shut off after 3-10 seconds
- Furnace cycles: tries to light, fails, tries again
- Eventually locks out after multiple attempts
Standing Pilot Light Problems
Older furnaces have a continuously burning pilot light. If your pilot won't stay lit:
| Problem | Likely Cause | Solution |
|---|---|---|
| Pilot won't light at all | Gas off, blocked orifice, failed gas valve | Check gas supply, clean orifice, test valve |
| Pilot lights but goes out | Bad thermocouple (most common) | Replace thermocouple ($50-100) |
| Pilot flame is weak/yellow | Dirty orifice, drafts, improper gas pressure | Clean orifice, check venting, adjust pressure |
| Pilot OK but burners won't light | Gas valve, control board, high limit | Further diagnosis needed |
The Thermocouple Explained
A thermocouple is a safety device in standing pilot systems. It sits in the pilot flame and generates a small electrical signal. This signal keeps the gas valve open. When the pilot goes out, the signal stops, and the gas valve closes — preventing gas from flooding your house.
Thermocouples fail over time. If your pilot won't stay lit after you release the button, the thermocouple is almost certainly the problem.
High Altitude Ignition Issues
- Thinner air affects combustion — flames burn differently
- Gas pressure settings must be adjusted for altitude
- Improper altitude adjustment causes ignition problems
- New furnace installations MUST be altitude-adjusted
If your furnace was moved from a lower elevation or installed without altitude adjustment, ignition problems are common. We verify and correct altitude settings during any ignition repair.
Furnace Won't Light: Troubleshooting Steps
- Check the thermostat: Is it calling for heat? Try raising temp 5 degrees.
- Check the furnace switch: Make sure it's in the ON position.
- Check the breaker: Is the furnace breaker tripped?
- Check the gas: Is the gas valve open? Do other gas appliances work?
- Look at the ignitor: Does it glow when the furnace tries to start?
- Watch the burners: Do they light and then go out? (Flame sensor issue)
- Check error codes: Many furnaces have a blinking LED that indicates the problem.
FAQ
Q: Can I clean the ignitor?
A: You can gently blow off dust, but don't touch the element with your fingers or scrub it. Oils from skin weaken the material. If it's cracked, it needs replacement.
Q: How do I relight a standing pilot?
A: Turn the gas valve to PILOT, hold down the reset button, and hold a flame to the pilot opening. Keep holding the button for 30-60 seconds after the pilot lights, then release slowly. If it goes out, the thermocouple is likely bad.
Q: Why does my furnace keep locking out?
A: Furnaces lock out after 3-5 failed ignition attempts to prevent gas buildup. Common causes: bad ignitor, dirty flame sensor, gas supply issues, or control board problems. You can reset most furnaces by turning off power for 30 seconds.