Noritz tankless water heater error codes

20 codes with causes and test steps, plus 3 settings tables.

Code	Meaning	Severity
06	Low recirculation flow (warning only)	Low
10	Abnormal combustion (NRCR, gas supply related)	High
11	Ignition failure (no flame detected)	High
12	Flame loss (repeated)	High
14	Thermal fuse failure	High
16	Abnormally high outlet temperature	High
20	High limit switch tripped	High
29	Condensate collector water level abnormal	Medium
061	Recirculation abnormality (sub-code of 06)	Low
062	Recirculation abnormality (sub-code of 06)	Low
63	Recirculation abnormality (no recirculation flow)	Medium
65	Main water control servo abnormality	Medium
66	Bypass water control servo abnormality	Medium
73	Circuit board setting abnormality	Low
90	Combustion abnormality	High
91	Gas conversion not done correctly	Critical
901	Combustion abnormality (sub-code of 90)	High
902	Combustion abnormality (sub-code of 90)	High
C1#	Descaling reminder (C11-C19)	Low
F76	Multi-system communication error	Low

Settings and specs

Indoor clearances (required and recommended)

Clearances · 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.
Near a kitchen range with indoor air supply, fit a non-combustible dividing plate wider than the heater.

Source: Noritz NRCR Pro training (NRCR92/NRCR111, Printable V3), Installation clearances, p.18

Operation panel menu settings and defaults

Control settings · 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).
Forgot screen lock password: hold OK 5 s while 'Input Password' is shown.
Menu also has Maintenance Monitor, Sys. Maint. Monitor (multi-unit), Error History (last 8) and Heater Info.

Source: Noritz EZ/NRCR Owner's Guide (Rev. 10-25), Configuring settings using the operation panel, p.15-20

Water quality limits

Specifications · Noritz EZ, Noritz NRCR

Contaminant	Max allowed
Total hardness	200 mg/L (12 gpg)
Aluminum	0.05 to 0.2 mg/L
Chloride	250 mg/L
Copper	1.0 mg/L
Iron	0.3 mg/L
Manganese	0.05 mg/L
pH	6.5-8.5
Total dissolved solids	500 mg/L
Zinc	5 mg/L
Sulfate	250 mg/L
Residual chlorine	4 mg/L

Damage from water above these levels, or from ignoring a C1# descaling reminder, is not covered by warranty.
Hardness and residual chlorine limits are Noritz suggestions; the rest are EPA secondary standards.

Source: Noritz EZ/NRCR Owner's Guide (Rev. 10-25), Water quality and maintenance, p.28

Models covered

EZ111DVEZ71DVEZ98DVN-0841MCN-0841MC-DVN-0842MCN-0842MC-DVNCC199-DVNCC199-SVNCC199CDVNRC111-DVNRC111-SVNRCR111DVNRCR92DV

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.