Troubleshooting common issues with natural gas furnaces: Start by checking the thermostat settings, ensuring the furnace is receiving power, inspecting the pilot light or ignition system, and examining the air filters for clogs to resolve heating inefficiencies and ensure safe operation.
A malfunctioning natural gas furnace can leave you shivering in winter. Before calling a technician, try these proven troubleshooting steps to restore heat quickly and safely.
No Heat Coming From Furnace
Check Thermostat Settings
Start with the thermostat. Ensure it’s set to “heat” mode and the temperature is at least 5°F above room temperature. Replace batteries if needed.
Inspect Circuit Breaker
Locate your home’s electrical panel. Check if the furnace breaker has tripped. Reset it if necessary. If it trips again immediately, contact an HVAC professional.
Verify Furnace Power Switch
Find the furnace’s power switch (usually a wall-mounted red switch near the unit). Make sure it’s in the “on” position.
Weak Airflow or Insufficient Heat
Replace Dirty Air Filters
Clogged filters restrict airflow. Check filters monthly during heating season. Replace disposable filters or clean permanent ones according to manufacturer instructions.
Check Vents and Registers
Ensure all supply vents are open and unobstructed by furniture or drapes. Closed vents force your furnace to work harder. For optimal performance, keep at least 80% of vents open.
Inspect Blower Motor
Listen for unusual noises from the blower. Scraping sounds may indicate worn bearings needing replacement. Regular maintenance prevents common blower issues.
Furnace Won’t Stay On
Pilot Light Problems
Older furnaces use a standing pilot light. If it’s out:
- Turn gas control knob to “off”
- Wait 5 minutes for gas to dissipate
- Turn knob to “pilot” and hold while lighting
- Keep holding for 30 seconds after ignition
Faulty Flame Sensor
Modern furnaces use electronic ignition. A dirty flame sensor can cause short cycling. Turn off power and gently clean the sensor with fine sandpaper.
Check Gas Supply
Verify the gas valve is open. If you smell gas, evacuate immediately and call your utility company from a safe location.
Unusual Noises
| Noise | Possible Cause | Solution |
|---|---|---|
| Screeching | Blower motor bearing failure | Professional lubrication or replacement |
| Rumbling | Dirty burners | Burner cleaning required |
| Popping | Duct expansion/contraction | Normal operation |
Preventative Maintenance Tips
Annual Professional Inspection
Schedule fall maintenance before heating season. A technician will check heat exchanger, gas pressure, and safety controls.
Keep Area Around Furnace Clear
Maintain 3 feet clearance around the furnace. Store flammable materials elsewhere.
Consider Upgrading Older Units
Furnaces over 15 years old may need replacement. Newer models like vented gas heaters offer better efficiency and reliability.
For complex issues or gas-related problems, always contact a licensed HVAC technician. The U.S. Department of Energy provides additional safety guidelines for gas furnace operation.
