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Rinnai · Tankless water heater

73 Burner thermocouple fault

High severity Non-SENSEIRH180 hybrid

What the control is telling you

Fault in the burner thermocouple circuit on Non-SENSEI units, which may stem from wiring, altitude DIP settings, manifold gas pressures, the thermocouple itself or the board.

Applies to: Non-SENSEI Series

Likely causes

  • Loose, broken or damaged thermocouple wiring
  • DIP switches not set for the installation altitude
  • Low/high fire manifold gas pressures off factory spec
  • Failed burner thermocouple
  • Faulty PC board

Test and repair steps

  1. Inspect the wiring from the burner thermocouple to the PC board for loose, broken or damaged wires or connections.
  2. Confirm all DIP switches are set for the installation altitude per the tech sheet under the front panel or the service manual.
  3. Warning: Only a person qualified to service gas systems should perform the following step.
  4. Confirm low and high fire manifold gas pressures meet factory specification for the altitude (settings in the tech sheet or service manual).
  5. Replace the burner thermocouple; if the code returns, replace the PC board.

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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.61. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.