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Rinnai · Tankless water heater

25 Condensate pump failure or clogged drain

Medium severity Non-SENSEIRH180 hybridSENSEI RX/CXSENSEI

What the control is telling you

Triggered when the condensate float/safety switch closes because condensate has backed up, or when the accessory condensate pump stops working.

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

Likely causes

  • No power to the condensate pump
  • External condensate pump not working
  • Clogged or frozen drain line
  • Loose or damaged wiring between pump/trap and PC board
  • Missing air gap in drain line
  • Restricted condensate trap

Test and repair steps

  1. Confirm the condensate pump has power.
  2. Check that the external (third-party) pump operates correctly.
  3. Make sure the drain line is not clogged or frozen.
  4. Inspect wiring from the pump and from the condensate trap back to the PC board for loose, damaged or broken connections.
  5. Confirm the drain line includes an air gap.
  6. Inspect the condensate trap for restrictions.

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Source: Rinnai Troubleshooting TWH Diagnostic Codes (100000652), p.34. 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.