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Noritz · Tankless water heater

91 Gas conversion not done correctly

Critical severity Noritz EZNoritz NRCR

What the control is telling you

EZ/NRCR: the unit's gas conversion was not completed correctly.

Applies to: Noritz EZ111/EZ98/EZ71 and NRCR111/NRCR92

Likely causes

  • LP orifice installed but gas type not changed in the app/display (or the reverse)
  • Gas conversion connector missing (NG to LP)
  • Wrong conversion kit

Test and repair steps

  1. Warning: Do not run the unit on LP until conversion is complete and verified; exhaust odor or burning eyes can mean a bad conversion.
  2. Confirm the kit CK-85 = NG to LP (includes the gas conversion connector), CK-84 = LP to NG.
  3. Check the orifice, o-rings and emission port cap gasket were replaced.
  4. Plug in the LP conversion connector and set the gas type in the EZ Start Plus app (Unit Setting > Convert Gas Type) or the display.
  5. Check inlet gas pressure and offset pressure at the gas valve with a digital manometer, and check combustion with a gas analyzer.
  6. Leak test, then fill out and attach the gas conversion sticker.

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Source: Noritz EZ/NRCR Owner's Guide (Rev. 10-25), Checking for error conditions / Gas conversion, p.31, 33; Noritz NRCR Pro training (NRCR92/NRCR111, Printable V3), Field gas conversion, p.3-6. 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.