If your gas furnace is only lighting one burner, it can be a frustrating and concerning issue. This detailed troubleshooting guide will help you understand the potential causes, step-by-step diagnosis, and methods to resolve the problem effectively.
What Causes a Gas Furnace to Have Only One Burner Lighting?
The most common reasons why a gas furnace may have only one burner lighting are:
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Faulty Ignition Systems: Issues with the igniter or hot surface igniter (HSI) can prevent multiple burners from lighting. If the igniter is not functioning correctly, it may only ignite the first burner.
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Gas Supply Issues: Low gas pressure or a malfunctioning gas valve can prevent sufficient gas from reaching all burners, resulting in only one burner lighting. Adjusting the gas pressure may resolve this issue, but it must be done carefully to avoid safety risks.
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Problems with the Burner Assembly: Clogged or dirty burners, or issues with the crossover tubes, can prevent the flame from spreading to other burners. Dirt, grime, or debris in the burners or orifices can block the gas flow.
How to Diagnose and Fix a Gas Furnace with Only One Burner Lighting?
Step 1: Check the Gas Pressure
- Use a manometer to verify the gas pressure is within the specified range (usually around 3.5 inches of water column).
- Adjust the gas valve if necessary, but ensure it is done correctly to avoid safety hazards.
Step 2: Inspect and Clean the Burners
- Remove the burner assembly and clean it thoroughly with a wire brush or compressed air.
- Ensure all orifices are clear of debris.
Step 3: Check the Ignition System
- Verify the igniter is functioning correctly. If it is faulty, replace it with a new one.
Step 4: Inspect the Crossover Tubes
- Ensure the crossover tubes are not pinched or blocked.
- Clean them if necessary using a small triangular piece of sheet metal or a fingernail file.
Step 5: Check the Flame Sensor
- Inspect the flame sensor for dirt or grime. Clean it if necessary.
- If the flame sensor is malfunctioning, replace it.
Common Problems and Solutions
| Problem | Solution |
|---|---|
| Clogged Burners | Clean the burners with a wire brush or compressed air. |
| Malfunctioning Valves | Check the gas valve for proper function. If faulty, replace it. Average cost: $100 to $530. |
| Dirty Flame Sensor | Clean the flame sensor. If it is malfunctioning, replace it. Average cost: $50 to $200. |
| Faulty Control Board | If the control board is faulty, it may need to be replaced. Average cost: $200 to $500. |
Estimated Costs and Timeframes for Repairs
| Component | Average Cost |
|---|---|
| Igniter | $50 to $200 |
| Gas Valve | $100 to $530 |
| Burner Assembly | $100 to $300 |
| Flame Sensor | $50 to $200 |
| Control Board | $200 to $500 |
The estimated timeframe for each repair step can range from 15 minutes to 1 hour, depending on the complexity of the issue and the technician’s experience.
