Rinnai Water Heater Error Code 22: How to Fix It

Q: What does error code 22 mean on a Rinnai water heater?

Error 22 indicates a flame control sensor fault. The sensor isn't detecting a proper flame, so the heater won't ignite or stay on. Common causes include a dirty sensor, loose wiring, or a defective sensor.

Q: Can I still use hot water with error 22?

No, the water heater will not operate with this error. The system shuts down as a safety precaution. You'll need to troubleshoot or call a technician to restore hot water.

Q: How do I clean the flame control sensor on my Rinnai?

Turn off power and gas, remove the front cover, locate the sensor (metal rod near burner), and gently clean it with fine-grit sandpaper or a soft brush. Wipe clean and reassemble.

Q: Do I need to replace the flame sensor or can I just clean it?

Cleaning often resolves the issue if there is soot or carbon buildup. If the sensor is damaged or cleaning doesn't help, replacement is necessary. A technician can diagnose and replace it.

Q: Will error 22 clear on its own?

No, the error requires manual troubleshooting. It won't reset until the underlying issue is fixed. Try cleaning the sensor and checking connections first.

Abstract

Error code 22 on a Rinnai tankless water heater indicates a flame control sensor fault. This means the unit's sensor isn't detecting a proper flame, which can prevent the heater from igniting or staying on. This guide will help you diagnose the issue with basic troubleshooting steps.