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Noritz · Tankless water heater

63 Recirculation abnormality (no recirculation flow)

Medium severity Noritz NRCR

What the control is telling you

NRCR only. The unit is running the built-in recirculation pump but sees no recirculation flow.

Applies to: Noritz NRCR92 / NRCR111

Likely causes

  • Clogged return line filter or closed shut-off valves
  • Air in the hot and return lines (dedicated return mode)
  • 'Crossover' connector not plugged together, crossover valve filter clogged or valve installed backwards (crossover mode)
  • Failed recirculation pump, recirculation flow sensor or circuit board (older installs)

Test and repair steps

  1. Check that the return line and water shut-off valves are open and clean the return line filter.
  2. Dedicated return purge air from the domestic hot and return lines.
  3. In crossover mode, make sure the 'Crossover' connector is plugged in, clean the filter on the crossover valve, and confirm the valve faces the right way.
  4. Check MM86 to confirm which recirculation mode the unit is set to and MM17 for recirculation flow.
  5. Use Trial Operation for the pump in the EZ Start Plus app.
  6. Older installs check the recirculation pump, recirculation flow sensor and circuit board.

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Source: Noritz EZ/NRCR/CDV Level 2 Maintenance & Troubleshooting (Premix R2 V2), 63 error code, p.14; Noritz NRCR Pro training (NRCR92/NRCR111, Printable V3), NRCR Pro specific error codes, p.29. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

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.