Home > rinnai tankless water heater code 12

How to fix Rinnai tankless water heater code 12?

Published on April 14th, 2022

If your Rinnai tankless water heater is displaying error code 12, it means that the unit is not receiving enough power. This can happen for a number of reasons, such as a tripped circuit breaker or a faulty power cord. If you suspect that the problem is with the power supply, you should contact an electrician to check the wiring and ensure that everything is up to code. Once the power issue has been resolved, the error code should clear and your Rinnai tankless water heater should return to normal operation.

Other common searches for this error include:

  • rinnai tankless water heater error code 12
  • rinnai tankless water heater code 12

1. Check the water heater's inlet and outlet for blockages

  1. Turn off the water supply to the water heater.
  2. Remove the cover and check the water inlet and outlet for blockages.
  3. If there are any blockages, clean them using a plunger or a vacuum cleaner.
  4. Reinstall the cover and turn on the water supply to the water heater.

2. Flush the water heater to remove any sediment that may have built up

  1. Turn off the water supply to the water heater.
  2. Open the drain valve on the water heater.
  3. Turn off the water supply to the house.
  4. Open the hot water faucet to the water heater.
  5. Turn on the cold water faucet to the water heater.
  6. Allow the water to run from the water heater for at least 30 seconds.
  7. Close the drain valve on the water heater.
  8. Turn off the water supply to the house.
  9. Turn on the hot water faucet to the water heater.
  10. Open the cold water faucet to the water heater.
  11. Check the water temperature in the hot and cold water lines. If the water temperature is too low, turn on the water heater to full power and wait until the water temperature reaches the desired temperature.
  12. Check the water temperature in the rinnai water heater. If the water temperature is too low, turn on the water heater to full power and wait until the water temperature reaches the desired temperature.

3. Check the water pressure to ensure it is within the operating range for the water heater

To check the water pressure, you will need to turn on the water and then check the pressure at the faucet. If the pressure is below the operating range, you will need to replace the rinnai tankless water heater.

If you didn't find success with an option above, then try:

  1. Replace the inlet screen if it is damaged or blocked.
  2. Replace the water heater if it is not repairable.