Rinnai Water Heater Code 12. Your gas water heater should get enough amount of gas. If you’re getting rinnai error code 12 on your hot water unit, it indicates that a flame failure has occurred on the system.
Rinnai code 12 indicates several issues within the rinnai water heater and that there is a lack of flame or flame failure within the system. This can be quite a difficult error code to solve yourself, especially if there are more extensive issues occurring within your unit. Verify low and high fire manifold pressures are set correctly.