72
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Rinnai · Tankless Water Heaters
Flame sensing device fault.
Quick Answer
Error code 72 on your Rinnai Tankless Water Heaters means: Flame sensing device fault.. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Inspect and clean flame rod carefully.
2
Check flame rod wire and connector for damage.
3
Verify proper electrical grounding.
4
Measure flame signal output during operation.
5
Replace flame sensing parts if readings are abnormal.
Pro Tip
This issue typically requires professional diagnosis. Attempting this fix without proper training could cause further problems.
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