Rinnai Water Heater Error Code 90: How to Fix It

Q: What causes Rinnai error code 90?

Error code 90 is caused by combustion abnormalities, typically due to blocked venting, incorrect gas type, dirty heat exchanger, faulty flame sensor, or inadequate gas pressure. Proper venting and gas supply are critical for safe operation.

Q: Is it safe to use my Rinnai water heater with error code 90?

No, do not operate the water heater with error code 90. This error indicates combustion problems that could lead to carbon monoxide production or other safety hazards. The unit should be inspected and repaired before use.

Q: How often should I clean my Rinnai water heater vents?

Inspect and clean vents annually or more frequently in areas with heavy debris, dust, or if you notice reduced performance. Regular maintenance prevents many combustion-related error codes including code 90.

Q: Can I fix Rinnai error code 90 myself?

Some causes like blocked vents or dirty flame sensors can be addressed by homeowners, but gas pressure issues, internal component failures, or complex venting problems require professional service. Always prioritize safety when working with gas appliances.

Q: How much does it cost to fix Rinnai error code 90?

Costs vary depending on the cause. Simple cleaning or minor vent repairs may cost $100-200 for service call, while component replacements like gas valves or control boards can range from $300-800 including labor.

Abstract

Rinnai error code 90 indicates a combustion abnormality in your tankless water heater, which means the unit is having trouble burning gas properly. This is a high-severity error that can be caused by blocked venting, incorrect gas type, or internal component failure.