You go to take a shower the water is cold and when you check your Rinnai tankless hot water heater it is displaying Error Code 12. Frustrating? Yes, but don’t worry – we’ve got you covered.

In this article, we’ll take you step-by-step through the troubleshooting process and show you how to fix Rinnai Error Code 12 and get your hot water flowing again. From checking the gas supply to inspecting the burner plate, we’ll cover everything you need to know to resolve whatever issue that is causing the flame failure. So, grab a cup of coffee, and let’s get started!

  1. Check Gas Supply:
  • Ensure that the gas is turned on at both the water heater and gas meter.
  • Check for any obstructions in the flue outlet. This can cause inadequate combustion and trigger error code 12.
  1. Verify Gas Line and Regulator Sizing:
  • Make sure that the gas line, meter, and/or regulator are sized properly to ensure that the heater receives the correct amount of gas.
  • Confirm that the gas type and pressure are correct by checking the manufacturer’s specifications for your model.
  1. Bleed Gas Lines:
  • To ensure that the gas is flowing smoothly, remove all air from the gas lines. This can be done by opening the gas valve and allowing the gas to flow for a few minutes.
  1. Check Venting:
  • Ensure that the proper Rinnai venting material was installed. This includes the right size, length, and materials.
  • Check that the condensation collar was installed properly. This helps prevent any moisture buildup.
  • Verify that the vent length is within limits. If the vent is too long or too short, it can cause the error code 12.
  1. Verify Dip Switch Settings:
  • Check that the dip switches are set properly according to the manufacturer’s specifications. The dip switches control various functions of the heater, and incorrect settings can cause the error code 12.
  1. Grounding:
  • Ensure that the appliance is properly grounded to prevent electrical malfunctions.
  • Check the ground wire for the PC board for any damage or loose connections.
  1. Disconnect Keypad and Controls:
  • Disconnect the keypad and any external controls like EZConnect or MSA to isolate the problem.
  • This can help determine if the issue is with the heater or the control panel.
  1. Check Power Supply:
  • Inspect the power supply for loose connections or damaged wiring.
  • Check that the power supply is providing the correct voltage and that there are no voltage drops that could affect the heater’s operation.
  1. Check Flame Rod and Wiring:
  • Ensure that the flame rod wire is connected and not damaged. The flame rod detects the presence of a flame, and a faulty connection can trigger the error code 12.
  • Check the flame rod for any carbon build-up that can prevent proper flame detection.
  • Disconnect and re-connect all wiring harnesses on the unit and PC board to ensure a good connection.
  1. Check for Electrical Shorts:
  • Inspect all components for electrical short circuits that could cause the error code 12.
  • Look for any signs of damage or corrosion that could affect the heater’s operation.
  1. Check Gas Solenoid Valves:
  • Check the gas solenoid valves for any open or short circuits that could prevent proper gas flow.
  • Inspect for any damage or corrosion that could affect the valve’s operation.
  1. Inspect Burner Plate:
  • Remove the burner plate and inspect the burner surface for any condensation or debris.
  • Ensure that the burner is clean and in good condition to allow proper combustion.
  1. Check the Ground Wire for the PC Board:
  • Check the ground wire for the PC board to ensure that it is properly connected and not damaged.
  • A faulty ground connection can cause the error code 12.

Hey, good news! If you followed the troubleshooting steps we shared above, and you were able to fix the Rinnai Error Code 12 and get hot water flowing again, way to go! But, if the issue persists and you’re still struggling with your tankless hot water heater, it’s probably a good idea to call in a professional plumber or HVAC technician for some extra help. Sometimes you just need a pro to identify and resolve a more complicated problem that might be causing the error code 12

Also, don’t forget to flush your Rinnai tankless hot water heater to prevent future issues and ensure it keeps performing at its best!

All the steps in this article were sourced from the Rinnai Official Troubleshooting PDF.