HVACopediaNoritz · Tankless water heater
12 Flame loss (repeated)
What the control is telling you
The burner lit but the flame went out and could not be held. Like code 11, low inlet gas pressure is a main cause. Same meaning on premix (EZ/NRCR/CDV) and non-premix (NRC/NRCP) units; only the allowed gas pressure range differs.
Applies to: All Noritz residential tankless (EZ, NRCR, NCC199CDV, NRC/NRCP)
Likely causes
- Inlet gas pressure too low under load (undersized gas line or meter)
- Dirty or poorly positioned flame rod
- Bad ground connections
- Incorrect venting (exhaust recirculating or blocked)
Test and repair steps
- Measure inlet gas pressure with the unit at full fire and other appliances running. 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.
- Remove, check and clean the flame rod (fine abrasive pad or 300+ grit sandpaper).
- Check and tighten ground connections at the board and chassis.
- Inspect the venting for wrong materials, poor termination or blockage; the deck shows incorrect venting as a cause.
- If the gas line is undersized, resize it per the installation manual gas tables (see Specs).
- If still flame loss, contact Noritz technical support (866-766-7489).
Settings for these units
Indoor clearances (required and recommended) · Noritz NRCR
| Location | Required | Recommended (service) |
|---|---|---|
| Top | 12 in. (300 mm) | 3 in. (76 mm) above and below exhaust |
| Front | 4 in. (100 mm) | 24 in. (610 mm) |
| Sides | 3 in. (76 mm) | 8 in. (203 mm) |
Required clearances apply to both combustible and non-combustible materials.
Recommended space is for service and quick access to gas and water shut-offs.
Operation panel menu settings and defaults · Noritz EZ, Noritz NRCR
| Setting | Options | Default |
|---|---|---|
| Max Set Temperature (power off) | 100-140 F in 5 F steps; 37-48 C, 50-60 C | 120 F / 50 C |
| Recirc ON/OFF | ON / OFF | OFF |
| Recirc Mode | Always OFF, Always ON, Manual Timer, Auto Learning (NRCR) | Always OFF |
| Vacation Mode | Active / Inactive | Inactive |
| Flow Meter Alarm | 10-60 gal (5 gal steps), 70-100 gal (10 gal steps), OFF | Alarm OFF |
| Drain Water (power off) | Start / Cancel | Cancel |
| Scale Flushing (power off) | Start / Cancel | Cancel |
| Audible Alarm | ON / OFF | ON |
| Screen Lock | Active / Inactive (4-digit password) | Inactive |
| Units (first 10 min after power-up, power off) | [F/gal/ft] or [C/L/m] | [F/gal/ft] |
| Power Saving Dis. / Backlight | ON-OFF / Power Save ON-OFF | ON / Power Save ON |
| Brightness / Contrast / Touch Sound | Bright-Normal-Dim-Dark / -15 to +15 / ON-OFF | Normal / Standard / ON |
Setting 125 F (55 C) or higher needs Max Set Temperature raised first; the panel warns about scald risk.
Default Settings resets everything in Settings except Screen Lock (hold OK about 5 s).
- Water quality limits · Noritz EZ, Noritz NRCR
Models that show this code
12 models in Noritz EZ, Noritz NRCR, Noritz CDV, Noritz NRC/NRCP
Other codes on the same units
- 06 Low recirculation flow (warning only)
- 10 Abnormal combustion (NRCR, gas supply related)
- 11 Ignition failure (no flame detected)
- 14 Thermal fuse failure
- 16 Abnormally high outlet temperature
- 20 High limit switch tripped
- 29 Condensate collector water level abnormal
- 061 Recirculation abnormality (sub-code of 06)
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Source: Noritz EZ/NRCR/CDV Level 2 Maintenance & Troubleshooting (Premix R2 V2), 12 error code, p.13; Noritz Residential Level 2 Maintenance & Troubleshooting (NRC/NRCP and older, R2 V1), 12 error code, p.7; Noritz NRCR Pro training (NRCR92/NRCR111, Printable V3), Gas line conditions, p.20. 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.