What does error code 72 mean on a Rinnai tankless water heater?

Flame rod fault. A fault with the flame sensing rod.

Can I fix Rinnai code 72 myself?

Start with these safe checks: Note the code. Flame rod cleaning and replacement are for a qualified gas technician.

When should I call a technician for code 72?

Flame rod cleaning and replacement are for a qualified gas technician. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Rinnai tankless water heater error code

Rinnai tankless water heater code 72: Flame rod fault

Rinnai tankless water heaters

What 72 means

A fault with the flame sensing rod.

Likely causes

Dirty or damaged flame rod
Loose connection

Safe first checks

Note the code.

When to stop

Flame rod cleaning and replacement are for a qualified gas technician.

Checked against: Rinnai: Troubleshooting Tankless Water Heater Diagnostic Codes (100000652). Codes can differ by model and year, so confirm with your owner's manual.