What You’ll Learn
How do I know what kind of pilot light my furnace has?
You can often identify your furnace’s ignition type by watching how it starts.
Significantly older furnaces may still have a standing pilot light, a small flame that burns continuously and ignites the burners when heat is needed. More commonly, systems rely on electronic ignition, which activates only when the furnace starts.
Depending on the system, you may see a glowing hot surface ignitor or hear a clicking spark just before the burners ignite.
In this blog:
The image is familiar to almost everyone: a small blue flame flickering inside a furnace.
For decades, that flame—the standing pilot light—was a standard part of home heating.
It became so common that many people still picture it when they think about how furnaces work.
But in reality, most furnaces don’t have pilot lights anymore. Modern systems use electronic ignition, lighting the burners only when heat is needed.
Still, the idea of the pilot light lingers.
Search online for furnace problems, and you’ll often see advice like “check if the pilot light went out.”
For many homeowners, though, that step no longer applies. Understanding whether your furnace uses a pilot light or electronic ignition can help you better diagnose problems and understand how your system works.
The Old Way: Standing Pilot Lights
A standing pilot light is a small flame that burns continuously inside the furnace.
When your thermostat calls for heat, the gas valve opens, and the burners ignite using that already-burning flame.
The downside of standing pilot lights is that the flame burns 24 hours a day, even when your furnace isn’t heating your home.
That means propane is being used continuously throughout the heating season.
While the amount is small, it adds up over time.
This is primarily why standing pilot lights have been largely phased out.
Starting in the 1980s, manufacturers began replacing standing pilots with electronic ignition systems that only ignite when the furnace runs.
By the early 2000s, electronic ignitors had become the standard in most new furnaces.
Do you have a Standing Pilot Light Furnace?
If you have a newer home, generally anything built after the 1990s, you likely do not have a standing pilot light.
Any home that had a full rehab, perhaps before you purchased, likely has a modern electronic-ignition furnace as well.
The easiest way to tell is by observing how your furnace starts.
A standing pilot system will have a small blue flame that burns continuously, even when the furnace isn’t actively heating your home. You may be able to see it through a small viewing window near the burner area.
The Current Way: Electronic Ignition
Modern propane furnaces typically use electronic ignition systems.
Instead of keeping a flame burning continuously, these systems ignite only when your thermostat calls for heat.
When the furnace starts:
- The ignition system activates
- The burners ignite
- Heat begins circulating through your home
Once the cycle ends, the ignition system shuts off completely.
For Pennsylvania homeowners dealing with long heating seasons, even small efficiency improvements can reduce fuel use over time.
The electronic ignition design improves efficiency and long-term operating costs because no fuel is wasted maintaining a constant flame.
The Three Types of Electronic Ignition
Today’s furnaces typically use one of three electronic ignition systems.
1. Hot Surface Ignitor (HSI)
The Hot Surface Ignitor is the most common ignition system in modern furnaces.
When the furnace starts, a small ceramic element heats up and glows bright orange—similar to a toaster’s heating element. Once it reaches the right temperature, the gas valve opens, and the burners ignite.
If you see a rod or small element inside the burner area glowing orange before the flame appears, your furnace likely uses a Hot Surface Ignitor.
HSI systems are popular because they are:
- Reliable
- Quiet
- Energy efficient
2. Intermittent Pilot Ignition (IPI)
This system works somewhat like a modern version of the traditional pilot light.
Instead of burning constantly, a small pilot flame ignites only when heat is needed.
After ignition, the main burners light, and the pilot shuts off again at the end of the heating cycle.
You may hear a clicking sound just before ignition as the system generates the spark to ignite the temporary pilot flame.
IPI systems eliminate the fuel waste of a standing pilot while maintaining a similar ignition method.
3. Direct Spark Ignition (DSI)
Direct Spark Ignition systems produce a visible spark to ignite the burners.
If you hear rapid clicking just before the burners ignite, your furnace likely uses Direct Spark Ignition.
This system operates and sounds similar to a gas stove’s ignition.
Because they ignite instantly, DSI systems are highly efficient and responsive.
When It Might Be Time to Upgrade Your Pilot Light Furnace
If your furnace still uses a standing pilot light, it may be a sign that the system is nearing the end of its lifespan.
Older furnaces often come with:
- Lower efficiency ratings
- Higher operating costs
- More frequent repairs
While a pilot light isn’t necessarily a problem on its own, it often indicates an aging system compared to modern propane furnaces.
Take Control of Your Home Heating
Understanding how your furnace ignites is a small detail that can reveal a lot about your system’s efficiency and age.
Whether your furnace uses a standing pilot light or electronic ignition, regular inspection and maintenance are essential for reliable winter performance.
Become a Kauffman Gas customer and let our technicians help ensure your propane heating system operates safely, efficiently, and reliably all winter long.
FAQs
Do propane furnaces still use pilot lights?
Some older propane furnaces still use standing pilot lights, but most modern systems use electronic ignition instead. Electronic systems are more efficient because they ignite only when heat is needed.
Is a standing pilot light unsafe?
Not necessarily. Standing pilots were widely used for decades and can operate safely when maintained properly. However, they do burn gas continuously and are less efficient than modern ignition systems.
Why did furnaces switch to electronic ignition?
Electronic ignition systems improve efficiency by eliminating the need for a constant flame. They also enable better control of the ignition process and reduce fuel waste.
Can a furnace run without electricity if it has a pilot light?
Some older pilot-light furnaces can operate without electricity because ignition does not rely on electronic components. However, many modern systems require electricity for blowers and control boards.
How do I know if my furnace is outdated?
If your furnace uses a standing pilot light, is over 15 years old, or struggles to maintain consistent heat, it may be time to consider an upgrade.