How to Reset Your Furnace Safely and Effectively

Resetting a furnace can resolve common faults such as a locked-out ignition, error codes, or a pilot light issue. This guide explains step-by-step resetting procedures for different furnace types, safety precautions, common causes for resets, and when to call a professional. Follow instructions carefully to avoid equipment damage or safety hazards.

Furnace Type	Typical Reset Location	Average Time
Gas Furnace With Reset Button	Control Panel Or Near Burner Compartment	5–10 Minutes
Electric Furnace	Breaker Panel Or Power Switch	10–15 Minutes
High-Efficiency Condensing Furnace	Control Board Or External Switch	10–30 Minutes

Why Reset A Furnace?

Resetting a furnace is a diagnostic and corrective action used to clear fault codes and restore normal operation after transient errors. It can help when the unit fails to start, trips a safety lockout, or shows repeated error lights. A reset does not fix underlying mechanical or electrical failures but can restart the control sequence if the issue was temporary.

Safety Precautions Before Resetting

Prioritizing safety reduces risk of fire, carbon monoxide poisoning, and electrical shock. Always shut off power and gas as required, and confirm the area is well-ventilated. If there is any smell of gas, evacuate and call the gas company or emergency services before attempting any reset.

• Turn Off Power: Switch off the furnace at the thermostat and the service switch near the unit; flip the breaker if necessary.
• Turn Off Gas: For gas furnaces, close the gas valve before inspecting internal components.
• Wait Briefly: Allow a few minutes for the control board to discharge and sensors to reset.
• Use Proper Tools: Use insulated tools and avoid touching live terminals when the power is on.
• Check For Leaks Or Odors: Stop and call a pro if gas odor or visible leaks are present.

Identifying Furnace Type And Controls

Different furnace models require different reset methods. Identifying the type helps locate the reset button or appropriate breaker. Common types include standard gas furnaces with a visible reset switch, high-efficiency condensing furnaces with control boards, and electric furnaces controlled via breakers.

Find Model And Manual

Locate the model number on the furnace cabinet and consult the manufacturer’s manual or website for model-specific reset instructions and error code definitions. Manuals often include wiring diagrams and recommended troubleshooting steps.

How To Reset A Gas Furnace With A Reset Button

Many gas furnaces include a manual reset button to clear a lockout. This button should be used sparingly, as repeated presses can conceal persistent faults.

1. Turn Off Thermostat: Set the thermostat to “Off” to stop calls for heat.
2. Shut Off Power: Turn off the furnace switch and flip the HVAC breaker off.
3. Locate Reset Button: Open access panel and find the red or yellow button labeled “Reset” or “Limit/Reset.”
4. Press And Hold: Press the button for 5–10 seconds; some models require a single press.
5. Restore Power: Replace access panel, turn the breaker on, switch power back on, and set the thermostat to heat.
6. Observe Operation: Allow the furnace to attempt ignition; if it cycles normally, the reset worked. If the button pops again or the unit locks out, stop and investigate the root cause.

Note: The limit/reset button is often associated with overheating or blocked exhaust issues. Repeated resets without resolving airflow or vent problems can be dangerous.

How To Reset A High-Efficiency Condensing Furnace

High-efficiency units use electronic control boards and may not have a simple reset button. Follow controlled power cycling and error-code clearing procedures instead.

1. Turn Off Thermostat And Power: Set thermostat to “Off” and switch off the furnace at the service switch and breaker.
2. Wait 5–10 Minutes: Allow the control board to power down and capacitors to discharge.
3. Check Error Codes: If the unit has an LED diagnostic display, record the blink code before resetting.
4. Power Back Up: Turn the breaker and service switch back on and set the thermostat to the desired setting.
5. Clear Codes If Needed: Some control boards require holding a specific button combo to clear stored codes; consult the manual.
6. Monitor Startup: Watch the ignition sequence; if the system fails again, note any error codes for technician reference.

How To Reset An Electric Furnace

Electric furnaces typically use fuses or breakers rather than ignition systems. Resetting focuses on restoring power and checking overcurrent issues.

1. Turn Off Thermostat: Set the thermostat to “Off.”
2. Flip Breaker Off: Turn off the furnace breaker at the electrical panel.
3. Inspect Safeties: Check for blown fuses, tripped disconnects, or burnt wiring; replace fuses only with the specified type.
4. Restore Breaker: Turn breaker back on and set thermostat to heat.
5. Observe Blower And Heaters: If the system trips the breaker again, stop and call an electrician.

Troubleshooting Common Causes Of Resets

Resetting often masks underlying faults. Identifying root causes prevents repeat lockouts and extends system life.

• Dirty Air Filter: Restricted airflow causes overheating and limit trips. Replace filters regularly.
• Blocked Vents Or Flue: Obstructions in intake or exhaust vents can trigger safety limits.
• Faulty Flame Sensor: Unsafe or inconsistent ignition causes repeated lockouts; cleaning or replacing the sensor often helps.
• Ignition Or Control Board Failures: Components may fail electronically and require professional replacement.
• Gas Supply Issues: Low gas pressure or a closed valve can prevent ignition; confirm supply before resets.
• Limit Switch Problems: A failed high-limit switch can trip unnecessarily and may need testing or replacement.

Interpreting Error Codes And Indicator Lights

Modern furnaces communicate problems through blink codes or digital messages. Recording codes helps technicians diagnose issues quickly.

Common Code Patterns

Short, repeating blink patterns often indicate a specific sensor or ignition error. Variations in blink count and pauses correspond to different fault types. Always consult the furnace manual for the exact meaning of codes for the user’s model.

When To Call A Professional

Resetting is a temporary fix if the cause is unclear or if safety-related components are involved. Contact a licensed HVAC technician under these conditions.

• Persistent Lockouts: If repeated resets are necessary, the furnace likely has an unresolved fault.
• Gas Smell: Evacuate and call the gas company or emergency services immediately.
• Electrical Repeated Trips: Breaker trips or burning smells indicate wiring or component failure.
• Complex Repairs: Ignition modules, control board replacements, and gas valve repairs require professional skills and permits.

Maintenance Steps To Prevent Future Resets

Routine maintenance minimizes the need for resets and improves safety and efficiency. A few simple tasks can make a big difference.

• Replace Air Filters: Change filters every 1–3 months depending on usage and filter type.
• Clean Flame Sensor And Burners: Annual cleaning by a technician improves ignition reliability.
• Inspect Vents And Chimney: Ensure clear intake and exhaust paths; remove debris or animal nests.
• Schedule Annual Tune-Ups: Professional inspections catch wear, leaks, and ignition issues early.
• Test Carbon Monoxide Detectors: Ensure CO detectors are functioning and replace batteries yearly.

Special Considerations For Older Furnaces

Older furnaces may lack modern safety features and diagnostic indicators. Reset approaches may be limited to power cycling and manual pilot relighting procedures set by the manufacturer.

Relighting A Pilot: Follow the manufacturer’s pilot relight instructions in the manual. If the pilot will not stay lit, gas valve or thermocouple replacement may be necessary.

DIY Checklist Before Attempting A Reset

Performing a quick checklist reduces wasted time and helps identify obvious issues before resetting the unit.

1. Check Thermostat Settings And Batteries.
2. Inspect And Replace Air Filter If Dirty.
3. Look For Error Codes And Record Them.
4. Ensure Vents, Flue, And Chimney Are Clear.
5. Confirm Gas Valve Is Open (If Applicable) And No Odor Is Present.
6. Turn Power Off At The Breaker, Wait, Then Turn Power Back On To Attempt A Reset.

Tips For Communicating With A Technician

Providing clear information speeds diagnosis and repair. Technicians rely on observed behavior, error codes, and recent actions to pinpoint problems.

• Note Exact Error Codes And Blink Patterns Observed.
• Describe Recent Events: Power outages, storms, or recent maintenance can be relevant.
• Report Any Smells: Gas, burning, or electrical odors should be emphasized.
• List Steps Already Taken: Mention resets performed and whether the furnace briefly restarted.

Key Takeaways

Resetting a furnace can resolve temporary control errors but is not a substitute for repairs. Always prioritize safety, shut off power and gas when required, and consult the owner’s manual for model-specific instructions. If problems recur, contact a licensed HVAC technician to diagnose and repair root causes.

For more detailed, model-specific guidance, consult the furnace manual or the manufacturer’s support resources.