HVACopedia

Rinnai · Tankless water heater

17 Venturi blockage

High severity SENSEI RX/CXSENSEI

What the control is telling you

The unit has detected a blocked venturi or restricted air path; after cleaning, a manual reset sequence on the PC board is needed to return to normal operation.

Applies to: SENSEI Series; SENSEI RX/CX Series

Likely causes

  • Condensate drain line not draining
  • Obstruction in intake, exhaust chamber or vent termination
  • Debris build-up in the venturi assembly

Test and repair steps

  1. Confirm the condensate drain line drains properly.
  2. Inspect the full vent system (intake, exhaust chamber, termination) for obstructions.
  3. Remove the gas valve and venturi assembly from the fan motor and inspect the venturi for debris.
  4. Clean the venturi assembly, reinstall it, then perform the code 17 reset on the PC board.
  5. SENSEI reset With controller off, press button B for 1 s repeatedly through t, F, S, E (E shows only with code 17/52 active), then hold A and B for 10 s until ECL appears.
  6. SENSEI RX/CX reset With controller off, press button B for 1 s repeatedly through dES, t, AdJ, F, A, E (E shows only with code 17/52 active), then hold A and B for 10 s until ECL appears.
  7. Once ECL is displayed the reset is complete and the water heater should resume normal operation.

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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.28–29. 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.