Where Is My Pilot Light on My Furnace and How to Find It Safely

The pilot light on a furnace can be easy to miss for many homeowners. This guide explains where pilot lights are commonly located, how to safely access and relight them, troubleshooting tips when the pilot won’t stay lit, and when to call a professional. The information covers older gas furnaces, gas water heaters, and boilers so readers can identify the correct pilot for their system.

System Type	Common Pilot Location	Typical Issues
Updraft Gas Furnace	Lower front panel or burner compartment behind removable panel	Dirty pilot orifice, thermocouple failure
Gas Water Heater	Access door near bottom of the tank	Draft, clogged orifice, flame out
Boiler	Near the burner assembly behind access panel	Faulty thermocouple, blocked pilot tube

How Pilot Lights Work

A pilot light is a small, continuous flame that ignites the main gas burner when heat is needed. Older gas appliances rely on a constantly burning pilot, while newer units often use an electronic ignition or hot surface igniter. The pilot assembly typically includes a pilot tube, pilot orifice, and a thermocouple or thermopile for safety shutdown.

Common Pilot Light Locations

Furnaces

On many older residential furnaces, the pilot light resides in the burner compartment located behind a removable lower front panel. Access often requires removing screws or pulling off a snap-in panel. Look for a small metal tube and a steady blue or yellow flame near the main burners.

Gas Water Heaters

Water heaters usually have a small access door or cover near the bottom. Open that cover to find the pilot assembly positioned near the bottom edge of the tank. The flame should be centered over the pilot orifice and should be steady and blue with minimal yellow tips.

Boilers

On boilers, the pilot light is located behind an access panel at the burner assembly. Some boilers have pilot windows or sight-glasses built into the panel so the pilot can be observed without removing the cover. If no window exists, the panel must be removed carefully.

Identifying Pilot Parts

Recognizing the pilot tube, pilot orifice, and thermocouple helps troubleshooting. The pilot tube is a small metal line delivering gas; the pilot orifice is a tiny opening where the flame forms; the thermocouple is a probe placed in the flame that senses heat and allows gas flow.

Safety Precautions Before Searching

Always shut off the gas valve when working on a pilot light unless relighting. Ensure adequate ventilation to prevent gas buildup. Avoid wearing loose clothing or open-toed shoes and keep ignition sources away from gas leaks. If a gas smell is present, evacuate and call the gas company immediately.

How To Relight A Pilot Light On A Furnace

Follow manufacturer instructions posted on the appliance. General steps include setting the control knob to “pilot,” holding it down, pressing the igniter or using a long match/lighter to ignite, and continuing to hold the knob for 30–60 seconds to heat the thermocouple. Release and verify the pilot stays lit.

Step-By-Step Relighting

1. Switch off the furnace and wait five to ten minutes if there is a gas smell.
2. Open the furnace access panel to reach the pilot assembly.
3. Turn the gas control knob to “pilot” and depress it to allow a flow of gas to the pilot.
4. Press the igniter button or use a long lighter to light the pilot while holding the control knob down.
5. Hold the knob for 30–60 seconds to heat the thermocouple, then release.
6. Set the control to “on” and replace the access panel.

Troubleshooting When Pilot Won’t Stay Lit

If the pilot lights but won’t remain lit, common causes include a faulty thermocouple, dirty pilot orifice, draft blowing out the flame, or issues with the gas control valve. Diagnostics narrow down the cause and inform whether repair or replacement is needed.

Thermocouple Problems

The thermocouple senses flame heat and keeps the gas valve open. If it fails, the pilot will not stay lit. Symptoms include a flame that extinguishes shortly after releasing the pilot control knob. A weak, corroded or misaligned thermocouple usually requires cleaning, repositioning, or replacement.

Clogged Pilot Orifice

Dirt and soot can obstruct the pilot orifice causing a weak flame that burns out easily. Cleaning with compressed air or a fine wire may restore flow, but excessive tampering can damage the orifice—seek professional help if unsure.

Drafts And Venting Issues

Strong drafts from nearby vents, fans, or a chimney draft problem can blow out the pilot. Ensure the appliance room is properly ventilated and that flue and chimney systems are clear and operating correctly.

Gas Supply And Pressure

Low gas pressure or partially closed valves may produce a weak pilot flame. If multiple gas appliances exhibit low flame or performance, contact the gas utility or a licensed technician to inspect pressure and supply lines.

When To Call A Professional

If relighting efforts fail, if the pilot repeatedly goes out, if there is a persistent gas smell, or if safety devices seem faulty, contact a licensed HVAC or gas technician. A pro can perform secure diagnostic tests, replace parts such as thermocouples and gas valves, and verify combustion and venting systems.

Converting From Pilot Light To Electronic Ignition

Many homeowners replace standing pilot systems with electronic ignition to save energy and improve reliability. Electronic ignition systems eliminate continuous pilot flame by using intermittent spark or hot surface igniters. A qualified technician should perform the conversion to ensure compatibility and compliance with codes.

Common Myths And Misconceptions

Myth: A yellow pilot flame is always bad. A small amount of yellow is normal for some gas types, but a large yellow or sooty flame indicates incomplete combustion or dirt. Myth: Pilot light problems only happen with old furnaces. While older units are more likely to have standing pilots, newer systems can also experience ignition issues if components fail.

Maintenance Tips To Prevent Pilot Issues

• Schedule annual professional inspections and tune-ups to catch problems early.
• Keep furnace and appliance compartments clean and free of dust and debris.
• Check pilot flame color monthly; a steady blue flame is ideal.
• Replace thermocouples at signs of corrosion or if pilot reliability declines.
• Consider upgrading to electronic ignition to eliminate continuous pilot maintenance.

How To Identify If The Pilot Is For The Wrong Appliance

Multiple gas appliances may be located close together. Verify the appliance model plate and the location of gas piping to ensure the pilot being inspected belongs to the furnace. If uncertain, trace the gas line visually or consult a technician to avoid tampering with the wrong unit.

Signs The Furnace Has Electronic Ignition Instead Of A Pilot

Modern furnaces often lack a continuous pilot. Indicators include a glowing hot surface igniter, a clicking sound at start-up, absence of a visible pilot flame, and an instruction label mentioning intermittent pilot or electronic ignition. Electronic systems are more energy-efficient and less likely to need relighting.

When A Pilot Light Is Not Visible

Some appliances include viewing windows or sight-glasses; others hide the pilot behind panels. If the pilot cannot be seen, check for a labeled pilot access or consult the owner’s manual. Removing panels may be necessary, but do so cautiously and follow safety instructions.

Dealing With A Gas Odor

If a gas odor is present, do not attempt to light anything. Leave the premises immediately, avoid electrical switches, and call the gas utility or emergency services from a safe location. A persistent odor indicates a potential leak and requires immediate professional action.

Replacement Parts And Costs

Typical pilot-related repairs range from inexpensive parts like thermocouples ($20–$100) to more costly gas valve replacements ($200–$600). Labor costs vary by region. Converting to electronic ignition can cost more upfront but may save fuel and reduce service calls over time.

Resources And Further Reading

Owner’s manuals, manufacturer instruction labels on the appliance, and reputable HVAC resources provide model-specific guidance. Utilities and local building departments offer safety advice and may provide inspection services. Always rely on licensed professionals for gas system repairs.

Key Takeaways

Locate Pilot in the burner compartment, access door, or behind an access panel. Relight Safely by following manufacturer steps and holding the control to heat the thermocouple. Troubleshoot thermocouple, orifice, draft, and gas supply if the pilot won’t stay lit. Call a Professional for persistent issues, gas odors, or conversions to electronic ignition.