Code 11 is one of the most common Rinnai tankless codes. It usually shows up with no hot water, and it often follows something simple, like a gas valve left partly closed after other work.
Safety first
If you smell gas, do not light anything or touch electrical switches. Leave the house and call SDG&E or 911 from outside. Manufacturers reserve gas, burner, venting and internal electrical work for qualified technicians.
Causes Rinnai lists for code 11
- Gas supply turned off at the water heater or the meter.
- Restricted airflow to the unit.
- Wrong gas type or gas pressure for the unit.
- A gas line, meter or regulator too small for the heater.
- Air in the gas lines, common after new installs or gas work.
- Poor electrical grounding.
What you can safely check
- The gas shutoff valve at the water heater is fully open.
- Gas service is on at the meter, and other gas appliances work.
- Nothing is blocking airflow around the unit or its vent terminal outside.
When to call a plumber
If gas is on, airflow is clear and code 11 keeps returning, call a licensed plumber or Rinnai service provider. Rinnai's documentation says only trained and qualified technicians should work on the product; gas pressure, line sizing and bleeding air from gas lines are technician jobs.
Common questions
Can I reset Rinnai code 11 myself?
You can make the safe checks (gas on at the heater and meter, nothing blocking the vent) and try again. If the code comes back, the cause needs a technician.
Why did code 11 appear after gas work or a new install?
Air in the gas line and incorrect gas pressure or line sizing are both on Rinnai's list of causes, and both are common after gas work. A technician can purge the line and test pressure.
General information, not professional or legal advice; follow your manufacturer's manual, and your installer and local permit office have the final word. Sources:Rinnai RL75i/RL94i technical sheet (diagnostic codes); Rinnai, Troubleshooting Tankless Water Heater Diagnostic Codes. SD Water Heaters is not affiliated with any manufacturer; brand names are used only to identify products, and codes can differ by model, so confirm in your own manual.
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