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Rinnai · Tankless water heater

72 Flame rod fault

High severity Non-SENSEIRH180 hybridSENSEI RX/CXSENSEI

What the control is telling you

The flame rod circuit is not sensing flame properly, due to wiring, rod position, carbon build-up, low flame current, a heat exchanger leak or a board fault.

Applies to: SENSEI Series, SENSEI RX/CX Series, Non-SENSEI Series

Likely causes

  • Broken or damaged flame rod wiring
  • Flame rod not contacting the flame
  • Carbon build-up on the flame rod
  • Flame current below 1 micro amp
  • Leaking heat exchanger
  • Faulty PC board

Test and repair steps

  1. Inspect the harness from the flame rods to the PC board for broken or damaged connections.
  2. Confirm the flame rod sits in the flame when the heater fires.
  3. Remove the flame rod and look for carbon build-up; replace the rod and gasket if needed.
  4. Measure flame rod output; it must hold at least 1 micro amp.
  5. Replace the flame rod and its gasket.
  6. Check the heat exchanger for leaks and replace it if necessary.
  7. Replace the PC board.
  8. SENSEI Transfer data from the old board with the supplied cable, or program all parameters manually per PCB Replacement Instructions (100000553).
  9. SENSEI RX/CX Transfer data from the old board with the supplied cable, or program all parameters manually per PCB Replacement Instructions (100000854).

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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.60. Summarized in our own words; check the original manual for your model.

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