How to Troubleshoot a Heil Furnace Pilot Light

The Heil furnace pilot light is a small but crucial component that ignites the main burner on many gas furnaces. This article explains common pilot light issues, safe relighting procedures, diagnostic checks, and when to call a professional. The guidance focuses on practical, safety-first steps for U.S. homeowners and HVAC technicians working with Heil systems.

Topic	Quick Take
Common Causes	Clogged pilot tube, faulty thermocouple, gas supply issues
Relighting Pilot	Follow Heil manual steps; ensure gas valve and power are off; vent area
Safety Checks	Gas smell, carbon monoxide detector, proper ventilation
When To Call Tech	Repeated outages, valve replacement, complex diagnostics

How The Heil Furnace Pilot Light Works

The pilot light provides a continuous flame to light the furnace’s main burners when heating is needed. Older Heil furnaces often use a standing pilot system, while newer models may use electronic ignition systems; however, many replacements and older units still rely on a pilot assembly. The pilot flame heats the thermocouple, which signals the gas valve to remain open.

Common Causes Of Pilot Light Problems

Understanding typical causes speeds diagnosis and repair. Clogged pilot tubes from dust, soot, or spider webs restrict gas flow and reduce flame stability. A faulty thermocouple fails to sense heat and closes the gas valve. Gas supply interruptions, drafts, and combustion air problems also extinguish the pilot. Mechanical issues with the gas control valve or regulator can prevent the pilot from lighting or staying lit.

Safety Precautions Before Troubleshooting

Prioritize safety. If a strong gas odor is present, evacuate the home and call the gas utility or emergency services. Turn off the furnace and gas supply before attempting any service. Ensure adequate ventilation and use a flashlight rather than an open flame when inspecting components. If a carbon monoxide alarm activates, leave immediately and contact professionals.

Tools And Materials Needed

Common tools for pilot light troubleshooting include a long-stem lighter or pilot lighting tool, adjustable wrench, screwdriver set, needle files or compressed air, a flashlight, and a multimeter for electrical checks. A replacement thermocouple and pilot assembly may be required. Always use approved parts that match the Heil furnace model number.

How To Relight A Heil Furnace Pilot Light

Relighting instructions vary by model; refer to the furnace manual. A general safe sequence is: turn the thermostat off, set the gas control to OFF and wait five minutes to clear gas, switch the control to PILOT, depress the pilot button, light the pilot with a long lighter, hold for 30-60 seconds to heat the thermocouple, then release and confirm the pilot stays lit before setting the control to ON. If the pilot won’t stay lit, stop and proceed to diagnostics.

Troubleshooting Steps If Pilot Won’t Stay Lit

If relighting fails, check the pilot flame shape—it should be steady and blue with a small inner cone. A weak or yellow flame indicates dirt or air/gas ratio problems. Gently clean the pilot orifice with compressed air or a fine wire; avoid enlarging the hole. Inspect and reposition the thermocouple tip so the flame envelops it directly. Test the thermocouple with a multimeter; a healthy thermocouple typically produces 25–30 millivolts when heated.

Checking The Thermocouple And Thermopile

The thermocouple converts heat to a small voltage to keep the gas valve open. Remove it from the valve and test output while heated by the pilot flame. A reading under manufacturer specifications indicates replacement is needed. Some Heil units use a thermopile for millivolt control systems; the replacement procedure and voltage expectations differ, so consult the furnace manual or tech sheet.

Cleaning And Maintaining The Pilot Assembly

Regular maintenance extends pilot life. Turn off gas and power, remove the pilot assembly cover, and use compressed air to clear debris. Avoid scraping or widening the orifice. Clean surrounding combustion areas to reduce soot accumulation. Inspect mounting brackets and flame shields for corrosion and replace damaged parts. Schedule annual professional maintenance to tune the burner and verify efficient combustion.

Gas Valve And Regulator Issues

If pilot problems persist after cleaning and thermocouple replacement, the gas control valve or regulator may be failing. Symptoms include no gas flow, inability to maintain pilot pressure, or intermittent pilot extinguishing despite correct thermocouple voltage. Replacing the gas valve should be done by a licensed technician because it involves gas line handling and system leak testing after installation.

Drafts, Venting, And Combustion Air Problems

Pilot lights can be extinguished by drafts from nearby doors, fans, or pressure imbalances in the home. Check that vent and chimney paths are unobstructed and balanced. For direct-vent Heil furnaces, verify intake and exhaust terminations are clear. Negative house pressure from exhaust fans or improperly sized venting can affect pilot stability, requiring adjustments to ventilation or HVAC balancing.

Electronic Ignition Alternatives And Upgrades

Many homeowners consider upgrading a standing pilot to an electronic ignition system to improve efficiency and reliability. Electronic ignition eliminates the constant pilot flame, reducing gas consumption and pilot-related failures. Conversion may require new control modules, igniters, and wiring, and should be performed by a qualified HVAC technician to ensure compatibility with the Heil furnace model and local codes.

Diagnostic Error Codes And Control Board Indicators

Modern Heil furnaces with electronic controls display LED codes or error messages. Consult the furnace’s wiring diagram and control board label for code definitions. Common indicators include lockout for failed ignition, flame sensing issues, or safety switch faults. Document blinking patterns and cross-reference the manual to pinpoint failed components before replacing parts.

When To Call A Professional Technician

Contact a licensed HVAC technician if the pilot repeatedly goes out, there is a suspected gas leak, the gas valve needs replacement, or electrical control diagnostics are required. Professionals can perform leak tests, combustion analysis for CO and efficiency, and safely handle gas control replacement and venting repairs. Homeowners should not attempt complex gas valve or regulator replacements.

Replacement Parts And Finding The Right Components

Use OEM Heil parts or approved equivalents for pilot tubes, thermocouples, gas valves, and pilot assemblies. Identify parts by furnace model number and serial code located on the furnace nameplate. Many parts distributors and HVAC service providers can cross-reference part numbers. Keep receipts and part numbers for warranty or future maintenance needs.

Preventive Maintenance Checklist

• Inspect the pilot flame for stable blue color monthly during the heating season.
• Schedule annual tune-ups that include burner cleaning, combustion testing, and pilot assembly inspection.
• Replace the thermocouple proactively if the furnace is older than 10 years or if readings trend low.
• Ensure venting and intake terminations remain clear of debris, nests, and snow.
• Test carbon monoxide detectors and change batteries regularly.

Common Myths And Misconceptions

Some believe the pilot flame should be large and visible; in fact, an efficient pilot is small and steady. Another misconception is that frequent relighting is normal; it indicates an underlying problem. DIY fixes are useful for cleaning and simple thermocouple swaps, but gas valve and regulator repairs require licensed technicians.

Cost Considerations And Typical Repair Prices

Costs vary regionally. Simple thermocouple replacement parts often cost $15–$60, with labor adding $75–$200. Pilot assembly cleaning during a service visit may be included in a $100–$200 tune-up. Gas valve replacement is more expensive, often $300–$700 for parts plus labor. Electronic ignition conversions run higher depending on parts and complexity.

Frequently Asked Questions

How Often Should The Pilot Be Checked?

The pilot should be visually checked at the start of the heating season and monthly during heavy use. Any flickering, yellowing, or smells warrants immediate inspection.

Is It Safe To Light The Pilot With A Match?

Using a long-stem lighter or the furnace’s built-in pilot light mechanism is safer. Avoid matches because they position the user too close to potential gas buildup. Always follow the furnace operator’s label instructions.

Can A Dirty Furnace Cause The Pilot To Go Out?

Yes. Dirt, soot, and dust can clog the pilot orifice and burner ports, disturbing the flame. Regular cleaning reduces these issues and improves combustion efficiency.

Resources And Manufacturer Guidance

Consult the Heil furnace owner’s manual and the product’s wiring diagram for model-specific instructions and safety information. Manufacturer technical support and licensed Heil dealers can provide installation sheets, part numbers, and authorized repair services. Verify local codes for any gas appliance work and obtain permits if required.

Key Takeaways For Homeowners

Regular inspection, proper cleaning, and timely thermocouple checks prevent most pilot light issues. If pilot problems persist after basic troubleshooting, engage a licensed HVAC technician for safe and code-compliant repairs. Prioritize gas-scent or carbon monoxide concerns by evacuating and calling emergency services or the gas company.