A Bryant gas furnace is a reliable and efficient heating system, but like any appliance, it can encounter issues that require troubleshooting. One common problem that Bryant gas furnace owners may face is the dreaded error code 31, which typically indicates a pressure switch fault. In this comprehensive blog post, we’ll explore the common causes of this error code, provide a step-by-step troubleshooting guide, and discuss potential blockages or issues in the vent pipe or intake.
What Causes Error Code 31 on a Bryant Gas Furnace?
Error code 31 on a Bryant gas furnace is often caused by a pressure switch fault. This can be due to several factors, including:
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Blocked or Clogged Drainage System: Moisture accumulation due to condensation can clog the drainage system, particularly the collector box and drain tube, preventing proper drainage and causing the furnace to think there is an issue with the exhaust pressure.
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Stuck Pressure Switch: The pressure switch can become stuck, preventing it from closing properly. This can often be resolved by gently tapping the switch or rocking the membrane with a chopstick or insulated dull screwdriver.
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Inducer Motor Issues: The inducer motor must be running to close the pressure switch. If the motor is not spinning, it could be due to a lack of voltage from the board or a burned-out motor.
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Venting Issues: Problems with vent sizing, length, and pitch, as well as blockages or ice buildup in the vent pipe, can prevent the pressure switch from closing. Proper installation according to the manual is crucial.
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Environmental Factors: Poor insulation of the exhaust pipe can lead to water condensation and accumulation, which can cause the error code.
Step-by-Step Troubleshooting Guide for Bryant Gas Furnace Error Code 31
To troubleshoot the error code 31 on your Bryant gas furnace, follow these steps:
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Power Off: Ensure the power to the furnace is turned off before starting any repairs.
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Check Pressure Switch:
- Verify if the pressure switch is stuck. Gently tap it or rock the membrane to unstick it.
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If the switch is not stuck, check if the inducer motor is running. If not, check for voltage to the motor using a multimeter.
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Inspect Drainage System:
- Check the collector box and drain tube for clogs. Disconnect the tube from the fan to the pressure switch and drain any accumulated water.
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Clean or replace the clogged components as necessary.
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Check Venting:
- Inspect the vent pipe for blockages, ice buildup, or poor pitch. Ensure the vent termination outside the house is correct.
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Use a vacuum cleaner in the blow position to test for blockages in the vent pipe.
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Measurements and Calculations:
- Check the pressure switch for the specified pressure rating (e.g., 1.58″wc) and ensure it matches the installation manual.
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Verify that the vent pipe is properly sized and pitched according to the manufacturer’s specifications.
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Reassemble and Test:
- Reconnect any disconnected components and turn the power back on.
- Monitor the furnace for proper operation and check for error codes.
Potential Blockages or Issues in Vent Pipe or Intake
When troubleshooting error code 31 on a Bryant gas furnace, it’s essential to inspect the vent pipe and intake for any potential blockages or issues.
Vent Pipe Blockages
- Check for ice buildup on the outside venting, especially during cold weather.
- Inspect the vent pipe for any blockages or kinks that could prevent proper airflow.
Intake Issues
- Ensure the fresh air intake is not blocked and is properly connected.
- Verify that the vent pipe is properly pitched and sized according to the installation manual.
What to Look For
- Gurgling Sounds: If you hear gurgling sounds from the drain trap, it indicates a blockage. Shut off the power and clean or replace the trap as necessary.
- Water Accumulation: Check for water accumulation in the collector box and drain tube, which can indicate a clogged drainage system.
Relevant Specifications
- Vent Pipe Specifications: Ensure the vent pipe meets the manufacturer’s specifications for size, length, and pitch.
- Pressure Switch Specifications: Verify the pressure switch rating matches the installation manual (e.g., 1.58″wc).
Reference Links
- Fix for Clogged Drainage (error code 31) on Bryant High Efficiency Furnace
- Diagnostic of 31 Pressure fault code on Carrier Bryant Payne 90 Furnace
- Bryant code 31 light – HVAC-Talk
By following the steps outlined in this comprehensive guide, you can effectively troubleshoot and resolve the common error code 31 on your Bryant gas furnace. Remember to always prioritize safety and consult a professional HVAC technician if you are unsure or uncomfortable with any of the troubleshooting steps.
