The Bryant Plus 90 furnace pilot light can sometimes go out or fail to stay lit, causing loss of heat and service interruptions. This article explains how the pilot system works, step-by-step relighting instructions, common causes of pilot light problems, safety precautions, and when to call a professional. It focuses on practical, safe troubleshooting for U.S. homeowners using Bryant Plus 90 systems.
| Issue | Quick Action | When To Call A Pro |
|---|---|---|
| Pilot Out | Follow relight procedure; check gas | If it won’t relight or stays out |
| Weak Flame | Clean pilot orifices; inspect thermocouple | If flame remains weak after cleaning |
| Thermostat Not Calling | Check settings and power | If electrical or control faults suspected |
How The Bryant Plus 90 Pilot System Works
The Bryant Plus 90 furnace uses a standing pilot or intermittent pilot ignition depending on the model and age. A pilot light produces a small, continuous flame that heats the thermocouple or flame sensor to allow the main gas valve to open. Newer variants may use a hot surface igniter or electronic ignition, which behave differently. Understanding which system the furnace uses is essential before attempting any troubleshooting.
Safety First: Precautions Before Working On The Pilot
Safety is the highest priority when handling gas appliances. Before any work, the furnace should be turned off and the area ventilated.
- Turn Off Power And Gas: Switch off electrical power to the furnace at the thermostat and circuit breaker, and turn the gas control knob to OFF if accessible.
- Ventilate The Area: Open windows and doors when a gas smell is present. Evacuate the area and call the gas company if the odor persists.
- Use Proper Tools: Use a long-reach lighter or match and non-sparking tools if needed. Avoid using open flames near gas leaks.
- If In Doubt, Call A Pro: For persistent issues, gas odors, or if the pilot won’t stay lit, contact a licensed HVAC technician.
Identifying The Pilot Type On A Bryant Plus 90
Determining the ignition type helps choose the correct procedure. The standing pilot is a small continuously burning flame near the burner assembly. Electronic or intermittent pilots will not show a constant flame and may rely on ignition controls or a hot surface igniter.
- Standing Pilot: Visible small flame when furnace is idle; has a pilot tube connected to gas valve.
- Intermittent Pilot / Electronic Ignition: No constant flame at idle; pilot only lights during call for heat or ignition is via hot surface element.
Step-By-Step: How To Relight A Standing Pilot On A Bryant Plus 90
The following steps describe relighting a typical Bryant Plus 90 standing pilot. If the unit uses electronic ignition, do not attempt this procedure.
- Locate The Pilot Assembly: Open the furnace access panel and find the pilot light, pilot tube, and gas control knob labeled “Pilot/On/Off.”
- Turn Off The Furnace: Set the thermostat to OFF and the furnace switch to OFF. Turn the gas control knob to OFF and wait five minutes to clear any residual gas.
- Set To Pilot: Turn the gas control knob to PILOT. Depress the knob or pilot button to allow gas to flow to the pilot orifice.
- Ignite The Pilot: While holding the pilot button, use a long-reach lighter or built-in igniter to light the pilot flame. Continue to hold the knob for 30–60 seconds after ignition.
- Release And Test: Slowly release the pilot button. The pilot should remain lit. Turn the gas control knob to ON and restore power to the furnace. Set the thermostat to a call-for-heat and confirm the main burners ignite.
Troubleshooting If The Pilot Won’t Stay Lit
If the pilot lights but goes out after releasing the button, common causes include a faulty thermocouple, pilot orifice blockage, or improper flame contact. The following checks can narrow the problem.
- Thermocouple Condition: Inspect the thermocouple tip for soot or damage. A dirty or bent thermocouple may not sense the flame. Replacement is often inexpensive and standard for older units.
- Pilot Flame Shape: The flame should envelop the thermocouple tip with a steady blue flame and minimal yellow. If the flame is weak or yellow, the pilot orifice may be clogged or air/gas mixture incorrect.
- Pilot Orifice Cleaning: Turn off gas, then remove and clean the pilot orifice using compressed air or fine wire. Avoid enlarging the orifice. Reinstall and test.
- Thermocouple Connection: Ensure the thermocouple nut at the gas valve is tight and free of corrosion. Replace the thermocouple if unsure about its condition.
When The Pilot Light Is Weak Or Yellow
A weak or yellow pilot flame indicates incomplete combustion, restricted gas flow, or dirt. This scenario can cause poor pilot sensing and burner ignition issues.
- Clean The Pilot And Burner Area To Remove Soot, Dust, And Debris.
- Check Venting And Air Supply To Ensure Proper Combustion Air.
- Verify Gas Pressure Is Within Specifications; Low Pressure Requires Utility Or Technician Intervention.
Thermocouple And Flame Sensor: Roles And Replacement
The thermocouple is a safety device that senses pilot flame heat. When the pilot flame heats the thermocouple, it generates a millivolt signal that keeps the gas valve open. Flame sensors in electronic ignition systems perform a similar role by detecting ionization from the flame.
Replacement Tips: Match the correct length and thread type when replacing a thermocouple. For flame sensors, gently clean with a fine abrasive pad before replacement. When uncertain, use OEM parts or consult a technician.
Common Causes Of Pilot Light Problems In Bryant Furnaces
Pilot light issues can stem from mechanical, electrical, or environmental factors. Identifying the root cause avoids repeated relighting attempts and improves safety.
- Clogged Pilot Orifice: Dust, spider webs, and debris restrict gas flow.
- Faulty Thermocouple Or Flame Sensor: Wear, corrosion, or misalignment prevents proper sensing.
- Gas Supply Issues: Closed valves, utility interruptions, or low gas pressure.
- Drafts Or Venting Problems: Strong drafts or blocked flues can extinguish the pilot.
- Age And Wear: Older units with mechanical controls are more likely to develop pilot problems.
Electronic Ignition Systems Vs. Standing Pilot
Many modern Bryant Plus 90 furnaces use electronic ignition to improve efficiency. These systems eliminate a constantly burning pilot and instead ignite the main burner when heat is needed. Electronic ignition faults manifest differently and often require diagnostic tools.
- Hot Surface Igniters: Fragile ceramic elements that can fail or become coated with carbon.
- Intermittent Pilot Modules: Control modules may fail or have faulty wiring.
- Diagnostic Codes: Modern units may blink LED codes that indicate specific failures; consult the manual to interpret them.
Maintenance Checklist To Prevent Pilot Issues
Regular maintenance reduces pilot and ignition problems and extends furnace life. A mix of homeowner checks and annual professional service is ideal.
- Inspect And Clean The Pilot Assembly Annually.
- Replace The Thermocouple Or Flame Sensor If Showing Wear.
- Keep The Furnace Area Free Of Dust And Debris.
- Check Vents And Chimney For Blockage Or Restriction.
- Schedule Annual HVAC Tune-Ups With A Licensed Technician.
When To Contact A Licensed HVAC Technician
Some problems require a professional due to complexity or safety. Contact a licensed technician for persistent pilot outages, gas odor, suspected gas leaks, or electronic ignition faults.
- Persistent Pilot Failure: Pilot won’t stay lit after cleaning and thermocouple replacement.
- Gas Smell Or Suspected Leak: Evacuate and call the gas company and an HVAC pro.
- Electrical Or Control Issues: Faulty control boards, transformers, or wiring should be handled professionally.
- Venting And Combustion Testing: Proper combustion analysis and venting checks require tools and expertise.
Replacement Parts And Costs For Common Pilot Repairs
Costs vary by region and whether a homeowner or technician performs the repair. Typical parts and approximate retail costs (U.S.) are listed below, excluding labor.
| Part | Typical Retail Cost |
|---|---|
| Thermocouple | $10–$40 |
| Pilot Orifice (repair/clean kit) | $5–$30 |
| Flame Sensor | $20–$70 |
| Hot Surface Igniter | $50–$150 |
Tips For Safe DIY Pilot Light Work
Homeowners can perform basic pilot relighting and cleaning, but safety and correct identification of the system are crucial.
- Always Turn Off Power And Gas Before Disassembly.
- Document Connections And Take Photos Before Removing Parts.
- Use OEM Or Equivalent Parts For Replacements.
- Avoid Over-Tightening Gas Fittings; Use Proper Sealants If Recommended.
- If The Pilot Smell Or Malfunction Persists, Stop And Call A Professional.
Resources And Manuals
Technical manuals and parts lists for Bryant Plus 90 furnaces are available from Bryant, Carrier, or authorized dealers. Model and serial numbers located on the furnace data plate help locate the correct documentation. For safety recalls or service advisories, check the U.S. Consumer Product Safety Commission and Bryant’s official site.
Key Takeaways
Pilot Light Maintenance And Safety Are Essential to ensuring a reliable Bryant Plus 90 furnace. Regular cleaning, inspection of the thermocouple or flame sensor, and timely replacement of worn parts will prevent most pilot problems. When a pilot won’t stay lit or a gas odor is present, professional service is strongly recommended to ensure safe repair and proper combustion performance.