Thermocouple
Common pilot and ignition part on gas water heaters.
Noritz NRCP Series Error Codes — What They Mean
The Noritz NRCP series (NRCP1112-DV, NRCP1262-DV) are direct-vent condensing tankless water heaters with efficiency ratings of 0.95–0.96 UEF. They display fault codes on the controller display or on the remote control panel. The NRCP uses PVC venting (Category IV) and produces condensate, which must be properly drained.
Noritz NRCP Error Code Reference
| Code | Meaning |
|---|---|
| 10 | Air supply or exhaust blockage |
| 11 | Ignition failure |
| 12 | Accidental flame extinction |
| 14 | Thermal fuse fault |
| 16 | Outlet water temperature overheat |
| 20 | Water temperature sensor fault |
| 21 | Secondary heat exchanger temp sensor fault |
| 29 | Neutralizer (condensate) fault |
| 31 | Flue gas sensor fault |
| 51 | Gas valve fault |
| 52 | Gas valve — failure to close |
| 57 | Combustion fan fault |
| 58 | Combustion air switch fault |
| 66 | Water flow sensor fault |
| 67 | Hot water temperature thermistor fault |
| 71 | Abnormal PCB |
| 90 | Exhaust temperature too high |
Common Causes by Code
- Code 10 — Air/exhaust blockage — A blocked intake or exhaust vent is the most common cause of Code 10 on the NRCP. Check both the combustion air intake PVC pipe and the exhaust PVC pipe at their exterior terminations. Birds, insects, and ice are frequent blockers.
- Code 11 — Ignition failure — Low gas pressure, fouled igniter, or a failed gas valve. On the NRCP, the igniter is a standard spark igniter — check gap and visible condition. Also confirm gas supply pressure with a manometer.
- Code 14 — Thermal fuse — One-time safety device in the exhaust path. Trips when exhaust temperature exceeds a safe limit. Root cause is typically a blocked exhaust, heavily scaled heat exchanger, or an abnormal firing condition. Replace only after correcting the root cause.
- Code 29 — Condensate fault — The NRCP condensate neutralizer is designed to raise the pH of the condensate before it enters the drain. If the neutralizer is clogged with calcium carbonate (common in hard water areas), Code 29 appears. Service or replace the neutralizer.
- Code 57 — Fan fault — Combustion fan motor failure. The fan must reach operating speed before ignition is permitted. A worn bearing, debris in the fan wheel, or a failed motor causes Code 57.
- Code 66 — Flow sensor — Water flow sensor fails to detect flow above the activation threshold (typically 0.5 GPM). Mineral scale on the flow sensor rotor is the most common cause. Remove and descale.
- Code 90 — Exhaust overtemp — Exhaust temperature has exceeded the high-limit setpoint. Usually caused by a blocked exhaust vent or heavy scale in the secondary heat exchanger restricting condensate flow.
Step-by-Step Fix
- Read the display — The NRCP display shows the error code when active. Note the exact code before resetting.
- For Code 10 — Inspect both PVC pipes at the exterior wall penetration. Confirm both intake and exhaust are clear. In winter, ice can form at the termination — clear it carefully.
- For Code 11 — Check gas supply at the meter and at other gas appliances. Inspect the igniter in the burner assembly — a cracked or heavily fouled igniter may need replacement.
- For Code 14 — Locate and test the thermal fuse for continuity. It is in the exhaust gas path near the heat exchanger. Before replacing, perform a descaling flush on the NRCP using the Noritz recommended descaling procedure (white vinegar flush, 45 minutes).
- For Code 29 — Remove the condensate neutralizer canister (if installed). Inspect and replace the neutralizer media (calcium carbonate granules). In hard water areas, this media depletes in 12–18 months.
- For Code 57 — With the unit off, access the combustion fan. Spin by hand — should rotate freely. Measure power supply voltage to the fan motor terminals during a startup attempt.
- For Code 66 — Remove the flow sensor assembly from the cold water inlet. Soak in white vinegar for 30–60 minutes to dissolve scale. Rinse and reinstall.
Parts Often Needed
| Part | Notes |
|---|---|
| Thermal fuse | One-time; must replace; fix root cause first |
| Neutralizer media | Calcium carbonate; annual replacement in hard water |
| Combustion fan | For Code 57 after obstacle check |
| Flow sensor | For Code 66 after descaling attempt |
| Gas valve assembly | For Code 51 after confirmed 24V signal |
| Secondary heat exchanger | For Code 90 due to scale — expensive; consider unit age |
Need Replacement Parts?
Before ordering, match the water-heating part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Gas valve replacement, thermal fuse investigation, and heat exchanger descaling should be performed by licensed technicians. If your NRCP is repeatedly tripping Code 14 or Code 90, the heat exchanger may be severely scaled — a professional descaling service can extend unit life significantly before replacement becomes necessary.