How to Light a Pilot Light on a Furnace? A Step-by-Step Guide
If your house is suddenly colder than it should be, don’t jump straight to panic — the culprit might just be a pilot light that’s gone out. Knowing how to light a pilot light on a furnace is one of those small skills that can save you a service call (and a chilly night). This guide from Green City Heating and Air Conditioning walks you through the process step by step, along with some troubleshooting tips and professional insight to help you get your heat back safely.
Understanding the Furnace Pilot Light
What Is a Pilot Light?
A pilot light is that small flame that stays lit continuously inside gas-powered furnaces. It’s job is simple but essential — it ignites the burners that actually produce the heat warming your home. No pilot light, no heat. That’s why learning how to light a pilot light on a furnace is worth having in your back pocket, especially once the weather turns.
Why Do Furnaces Have Pilot Lights?
In older furnace models, the pilot light is what ignites the natural gas flowing to the burners whenever your thermostat calls for heat. Newer systems have largely moved to electronic ignition, but plenty of homes — especially older ones — still rely on the classic pilot light setup.
Reasons Your Furnace Pilot Light Might Go Out
Drafts and Ventilation Issues
Sometimes it’s as simple as a stray draft or gust of wind snuffing out the flame. Leaky ductwork or a furnace sitting in a naturally drafty spot can make this a recurring headache.
Dirty or Malfunctioning Thermocouple
The thermocouple is a small safety sensor that confirms the pilot light is actually burning. When it gets dirty or damaged, it can mistakenly cut off the gas supply — which puts out the pilot light even though nothing else is technically wrong.
Gas Valve or Fuel Supply Problems
A malfunctioning gas valve or a low fuel supply can interrupt the gas flow enough that keeping the flame lit becomes a losing battle.
Worn or Faulty Furnace Components
Older furnaces naturally wear down over time, and that wear can affect the pilot light assembly along with other parts, making a steady flame harder to maintain.
Before You Start: Important Safety Precautions
Check for Gas Leaks
If you smell gas — even faintly — stop right there. Don’t attempt to light the pilot. Open some windows, get out of the house, and call a professional or your gas company right away. This step isn’t optional; it’s the single most important part of learning how to light a pilot light on a furnace safely.
Locate and Understand Your Furnace’s Instruction Manual
Your specific furnace model may have its own quirks, so check the manual if you have it. No manual on hand? The general steps below still apply — just keep safety front and center throughout.
Tools You’ll Need
- Long lighter or matches
- Flashlight
- Screwdriver (if the pilot light assembly is behind a panel)
How to Light a Pilot Light On Furnace?
Step-by-Step Guide to Relight a Furnace Pilot Light
1. Locate the Pilot Light Assembly
Look near the bottom of the furnace for a knob with three settings — “On,” “Off,” and “Pilot.” Finding this part is the first real step in figuring out how to light a pilot light on a furnace.
2. Turn Off the Furnace and Wait for Gas to Dissipate
Flip the gas valve to “Off” and give it at least 5 minutes before doing anything else. This lets any lingering gas clear out completely before you relight anything.
3. Switch the Gas Valve to “Pilot” Mode
Turn the valve to “Pilot.” This lets a small, controlled amount of gas reach the pilot light without engaging the main burners yet.
4. Press and Hold the Reset Button
Look for a reset button near the pilot assembly — most furnaces have one. Press and hold it to let gas flow to the pilot light itself.
5. Use a Long Lighter or Match to Ignite the Pilot Light
While still holding that reset button, bring your lighter or match close to the pilot opening until the flame catches. Keep holding the button for another 30-60 seconds afterward — this gives the flame time to stabilize before you let go.
6. Switch the Gas Valve to the “On” Position
Once the pilot’s burning steadily on its own, switch the valve to “On.” Put any access panels back in place and turn your thermostat up to confirm the furnace kicks in properly.
Signs of a Problem After Relighting the Pilot Light
- The Pilot Light Won’t Stay Lit: Usually points to a faulty thermocouple, a clogged pilot opening, or a gas supply issue.
- The Flame Color Isn’t Blue: A yellow or flickering flame is a sign there’s dirt or debris somewhere in the gas line or pilot assembly.
- Persistent Gas Smell: If the smell doesn’t go away, shut the system down and call a professional immediately — don’t wait this one out.
Catching these warning signs early makes all the difference when you’re troubleshooting how to light a pilot light on a furnace and trying to keep things running smoothly.
Troubleshooting Common Pilot Light Issues
Cleaning a Dirty Thermocouple
A grimy thermocouple can fail to sense the pilot flame at all, which shuts off gas flow unnecessarily. A gentle pass with fine sandpaper on the tip usually does the trick and restores proper sensing.
Adjusting a Bent Thermocouple
If the thermocouple’s sitting too far from the flame, it won’t detect it properly. Carefully repositioning it so it sits just above the pilot flame usually solves this.
Addressing a Clogged Pilot Light Opening
Debris in the pilot opening can make it tough for the flame to stay lit. Turn off the gas first, clear the opening gently with a thin wire, then try relighting. Keeping this area clean is a big part of making the whole process of how to light a pilot light on a furnace go smoothly every time.
Preventing Future Pilot Light Problems
Regular Furnace Maintenance Tips
- Book an annual furnace inspection to keep everything in working order.
- Clean the pilot assembly and thermocouple periodically to keep dirt from building up.
Ensuring Proper Ventilation Around the Furnace
Keep your furnace somewhere free of drafts, with good airflow and nothing blocking the vents.
Keeping the Thermocouple Clean
Make thermocouple inspection part of your routine maintenance checks, cleaning it whenever needed to keep it working reliably.
When to Call Green City Heating and Air Conditioning
If you’ve tried relighting the pilot and it’s just not sticking — or you suspect something bigger is going on — that’s your cue to call in the pros. At Green City Heating and Air Conditioning, our licensed technicians handle everything from simple pilot light issues to more complex furnace problems, keeping your home safe and warm either way. Our team has plenty of experience helping homeowners who’ve struggled with how to light a pilot light on a furnace or run into the same issue over and over.
Why Choose Green City Heating and Air Conditioning?
- Expertise in Gas Furnace Maintenance and Repairs: Years of hands-on experience means we know how to solve pilot light problems and everything else that comes with furnace upkeep.
- Licensed Technicians for Safe and Efficient Solutions: Every technician on our team is trained with safety and efficiency as top priorities on every call.
- Comprehensive HVAC Services to Meet All Your Heating Needs: From routine tune-ups to more involved repairs, we’ve got it covered.
Contact Green City Heating and Air Conditioning
Licensed and bonded, with a 5-star BBB rating, Green City Heating and Air Conditioning takes pride in delivering quality HVAC service. We work with trusted manufacturers like Daikin, Lennox, and Navien, so you can count on solid solutions for your Washington home.
Need a hand relighting your pilot light or keeping your furnace in shape? Request a quote online or give us a call at (206) 201-0835. Whether this is your first time figuring out how to light a pilot light on a furnace or you’re dealing with something trickier, we’re happy to help.
Follow this guide, stay on top of maintenance, and your furnace should keep running the way it’s supposed to. And if things ever get more complicated than a pilot light, you know where to find us.
