Furnace Pilot Light vs. Electronic Ignition: What Minnesota Homeowners Need to Know

If your furnace was built before 1990, it likely has a standing pilot light—a small continuous flame that stays lit all the time, ready to ignite the main burner when the thermostat calls for heat. Nearly all modern furnaces use electronic ignition instead. Understanding the difference matters if you're troubleshooting a furnace that won't start, comparing old equipment to new, or trying to decide whether to repair or replace an aging system.

Standing Pilot Lights: How They Work

A standing pilot is a small continuously burning flame, typically fueled by a trickle of natural gas. When the thermostat calls for heat, the main gas valve opens, and the pilot flame ignites the main burners. A thermocouple (a simple temperature-sensitive device) monitors the pilot flame and keeps the gas valve open as long as the pilot is lit. If the pilot goes out, the thermocouple cools, closes the gas valve, and prevents unburned gas from flowing.

Advantages of standing pilots:

• Simple and reliable—very few components to fail
• Works during power outages (the pilot and thermocouple require no electricity)
• Easy to relight if it goes out—instructions are printed on the furnace

Disadvantages:

• Wastes gas continuously—a standing pilot consumes 5–12 therms per month even when the furnace isn't running
• Only found on older furnaces, typically 30+ years old in Minnesota
• If the pilot goes out repeatedly, the thermocouple is likely failing ($20–$60 part)

Electronic Ignition: Two Types

Intermittent Pilot (Spark Ignition)

Intermittent pilot systems use an electric spark to light a pilot flame only when heat is called for. The pilot then lights the main burners, and once the burners are confirmed lit (by a flame sensor), the pilot goes out. This eliminates the continuous gas waste of a standing pilot while still using a pilot flame as the intermediate step.

• Common in furnaces from approximately 1985–2000
• You'll hear a clicking sound when the furnace calls for heat (the spark igniter)
• More efficient than standing pilot; still has spark module that can fail

Hot Surface Ignition (HSI)

Hot surface igniters are the standard in virtually all furnaces made since the mid-1990s. A small silicon carbide or silicon nitride element heats to 1,800–2,500°F when powered, directly igniting the gas when the burner opens. No pilot flame needed at all.

• You'll see (or hear) no clicking—just a pause while the igniter heats up, then the burner lights
• Very efficient—no pilot gas waste whatsoever
• Most common failure point in modern furnaces (typically $15–$30 for the part; $150–$300 installed)
• Silicon carbide igniters are more fragile; silicon nitride igniters are more durable

How to Tell Which Type Your Furnace Has

• If your furnace was made before 1985: almost certainly a standing pilot
• If you hear clicking before the burner lights: intermittent pilot (spark ignition)
• If there's a quiet pause before the burner lights with no clicking: hot surface igniter
• You can also check the furnace manual or look at the burner assembly—a hot surface igniter is a small, rectangular, fragile-looking element near the burner orifices

Common Ignition Failure Symptoms in Minnesota

Minnesota's cold climate puts particular stress on ignition systems:

• Furnace tries to start but won't light (no burner flame): Hot surface igniter may be cracked or failed; or flame sensor is dirty and not confirming ignition
• Furnace lights then shuts off quickly: Dirty flame sensor (coated with oxidation, preventing current flow); this is the most common "nuisance shutdown" in Minnesota
• Clicking continuously but pilot won't light: Weak spark, dirty pilot orifice, or failed ignition control module
• Standing pilot won't stay lit: Failing thermocouple (most likely) or draft that's blowing out the pilot

See our Goodman error code guide for specific fault codes related to ignition failures, and our emergency furnace repair guide for what to do when heat fails.

DIY Flame Sensor Cleaning (Most Common Fix)

A dirty flame sensor is responsible for a huge proportion of "furnace shuts off after lighting" calls in Minnesota. The flame sensor is a metal rod that extends into the burner flame; it carries a small electrical current that confirms the burner is lit. Oxidation on the sensor insulates it, preventing current flow and causing the furnace to shut down on safety.

Cleaning the flame sensor is within reach for mechanically inclined homeowners:

1. Turn off the furnace power switch and gas valve
2. Remove the burner access panel
3. Locate the flame sensor (one metal rod with a wire connected, positioned in the burner flame path)
4. Remove the single mounting screw and slide out the sensor
5. Gently clean the metal rod with fine steel wool or light sandpaper until it's shiny
6. Reinstall and test

If cleaning doesn't resolve the issue, the sensor may need replacement ($20–$40 part). Always call a professional if you're uncomfortable with any step.

The Case for Modern Electronic Ignition

If you have an older furnace with a standing pilot, you're wasting 60–140 therms of gas per year just keeping the pilot lit—potentially $60–$150 in fuel annually with no heating benefit. That's one of many reasons why replacing an old standing-pilot furnace with a modern 96% AFUE electronic ignition unit saves money quickly.

Browse our factory-direct Goodman furnaces for modern, efficient replacement options—all with hot surface ignition, 96% AFUE, and 10-year warranties.