How to Troubleshoot an Intertherm Gas Furnace That Turns On but Won't Ignite

When an Intertherm gas furnace starts up but fails to ignite, it can be a frustrating issue. Understanding the steps to troubleshoot this problem can be crucial in resolving it safely and effectively. This guide provides a comprehensive breakdown of the process, helping you identify and possibly address the underlying issue.

Safety First

Troubleshooting any home appliance, including an Intertherm gas furnace, requires prioritizing safety. Before proceeding, ensure the safety of yourself and your home by following these steps:

Turn Off Power: Ensure the furnace is powered down by turning off the circuit breaker. Check Gas Supply: Ensure the gas supply is turned on and there are no gas leaks. If you smell gas, evacuate the area and contact a professional immediately.

Troubleshooting Steps

Inspect the Thermostat

Ensure the thermostat is set correctly:

Check the thermostat settings to ensure they are appropriate for the desired temperature. Incorrect settings can lead to issues in the ignition process.

Check the Air Filter

A dirty air filter can restrict airflow:

Replace or clean the filter if it’s dirty. A clogged filter can impair the furnace’s ability to work properly.

Examine the Furnace Door

Ensure the furnace door is securely closed:

Many models have safety switches that prevent operation if the door is ajar. Verify that the door is fully closed.

Inspect the Ignitor

Check the ignitor for cracks or damage:

If the ignitor isn’t glowing when the furnace attempts to ignite, it may need replacement. A non-functioning ignitor can prevent the ignition process.

Examine the Flame Sensor

A dirty flame sensor can prevent the furnace from igniting:

Clean the sensor with fine sandpaper or a soft cloth to ensure it operates correctly. Dirty sensors can lead to ignition failures.

Check for Blocked Vents

Ensure vents are not blocked:

Examine both the exhaust and intake vents for any debris or snow that might be obstructing them. Blocked vents can impede the proper function of the furnace.

Look for Error Codes

Review the diagnostic light for error codes:

Many modern furnaces have a diagnostic light that displays error codes. Refer to the user manual to interpret the blinking patterns and take appropriate action.

Inspect the Gas Valve

Ensure the gas valve is open:

If the valve is closed, the furnace will not ignite further. Adjust the settings to open the valve.

Check the Blower Motor

Ensure the blower motor is functioning properly:

Listen for any unusual noises or check for lack of motion. A malfunctioning blower motor can prevent the furnace from operating correctly.

Reset the Furnace

For some models, reset the furnace by:

Turning off the power to the furnace for a few minutes and then turning it back on. This can help reset any transient faults that may be causing the issue.

When to Call a Professional

If you've tried these steps but the furnace still won't ignite, it may be time to call a qualified HVAC technician.

There could be more complex issues such as problems with the control board, gas pressure, or other internal components.

Conclusion

Regular maintenance can prevent issues with your gas furnace. If troubleshooting does not resolve the issue, consider scheduling a professional inspection to ensure safe and efficient operation.

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