Rinnai
-
⛔ Do Not Use
Rinnai - Error Code 72
Rinnai Water Heater error code 72: Flame rod failure.
Is it safe?
⛔ No — stop using
Do NOT operate — potential gas or CO hazard. Ventilate the area and call a technician immediately.
Can I fix it?
Technician Required
Repair cost
Pro: $150–$600
⏱ 1–3 hours (pro)
What Does Error Code 72 Mean?
Rinnai Water Heater error code 72: Flame rod failure.
Part that typically fails: Gas valve / igniter / heat exchanger
Do NOT operate — potential gas or CO hazard. Ventilate the area and call a technician immediately.
Symptoms You May Notice
- ⚠️ No hot water
- ⚠️ Unit clicking but not firing
- ⚠️ Cold water only
What the Technician Will Do
🔧 Professional repair required. Do not attempt DIY — this repair requires specialized tools or certification.
- 1 Check your owner's manual for model-specific guidance on error code reset procedures
- 2 Check that gas supply valve is fully open and gas supply pressure is adequate
- 3 Clean the flame sensor rod with fine steel wool — carbon buildup is the #1 cause
- 4 Ensure the venting (exhaust and air intake pipes) are clear of obstructions, ice, or debris
- 5 If the error persists after reset and basic checks, contact a qualified technician
⚡ Quick tip: Always try a full power reset first — turn the unit off at the breaker, wait 30 seconds, restore power.
Frequently Asked Questions
What does Rinnai Water Heater error code 72 mean? ▼
Error code 72 on a Rinnai tankless water heater indicates: Flame rod failure. The unit has detected this condition and has limited or stopped operation to prevent further damage.
How do I fix Rinnai Water Heater error code 72? ▼
Start by powering the unit off for 30 seconds and restarting. If error 72 returns, the underlying cause (flame rod failure) needs to be addressed. Check wiring connections and filters first before replacing components.
Is Rinnai error code 72 serious? ▼
It depends on the root cause. Some 72 errors resolve with a reset. Others indicate a failed component that requires professional repair. Don't continue operating with this error — it can lead to further damage.