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Noritz · Tankless water heater

11 Ignition failure (no flame detected)

High severity Noritz EZNoritz NRCRNoritz CDVNoritz NRC/NRCP

What the control is telling you

The burner did not light or the flame rod never saw flame. Noritz points to the three things needed to burn: air, fuel and spark; with the front cover off air is rarely the cause, so start with gas pressure and the ignition/flame rods. Same meaning on premix (EZ/NRCR/CDV) and non-premix (NRC/NRCP) units, but the allowed inlet gas pressures differ by family. On EZ/NRCR, 11 can also show briefly after manual draining (owner's guide) and is not a fault then.

Applies to: All Noritz residential tankless: EZ, NRCR, NCC199CDV (premix) and NRC/NRCP and older (non-premix)

Likely causes

  • Gas valve closed, empty LP tank or gas cut off at the meter
  • Inlet gas pressure outside the range (undersized gas line, meter too small, water/debris in the gas line, earthquake shutoff valve)
  • Air in a new gas line
  • Dirty or damaged ignition rod / flame rod
  • Poor ground connections
  • Debris or insects in the burner (non-premix)

Test and repair steps

  1. Confirm the manual gas valve is open and, on LP, that the tank has gas (do other gas appliances work?).
  2. Reset close and reopen the hot water fixture, or turn power off and on. On a new install repeat a few times to purge air from the gas line.
  3. Measure static and dynamic inlet gas pressure with a digital manometer at the inlet tap. Premix (EZ, NRCR, NCC199CDV) inlet gas: NG 3.5-10.5 in. WC, LP 8-14 in. WC. NRC/NRCP inlet gas: up to 199k Btu/h NG 4-10.5 in. WC, LP 8-14 in. WC; over 199k Btu/h NG 5-10.5 in. WC, LP 10.5-14 in. WC.
  4. Test inlet pressure under low (1-2 fixtures), moderate (3-4), high (5+) and worst-case demand (5+ fixtures plus all other gas appliances). If it drops out of range, resize the gas line per the installation manual.
  5. Take out the flame and ignition rods (premix units: 2 screws). Rub them clean using 300+ grit sandpaper, a Scotch-Brite pad, or a sponge's rough side.
  6. Check the ground wires and connections at the board and chassis.
  7. Non-premix (NRC/NRCP) look through the burner window and inspect the burner for debris or insects.
  8. If the code returns after the checks, contact Noritz technical support (866-766-7489) with model and serial number.

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Source: Noritz EZ/NRCR/CDV Level 2 Maintenance & Troubleshooting (Premix R2 V2), Common error codes / 11 error code, p.11, 13; Noritz Residential Level 2 Maintenance & Troubleshooting (NRC/NRCP and older, R2 V1), 11 error code, p.6-7; Noritz NRCR Pro training (NRCR92/NRCR111, Printable V3), Gas line conditions, p.19-20; Noritz EZ/NRCR Owner's Guide (Rev. 10-25), Checking for error conditions, p.31. 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.