Noritz Tankless Water Heater Troubleshooting: 8 Common Problems and Fixes

Quick Answer

Common Noritz tankless water heater problems include no hot water, error codes on the display, water that cycles between hot and cold, ignition failures, and condensate drainage issues.

Common Noritz tankless water heater problems include no hot water, error codes on the display, water that cycles between hot and cold, ignition failures, and condensate drainage issues. Most issues trace to one of four root causes: an active error code (check the display and use the specific code guide), flow rate below the 0.5 GPM activation threshold, scale buildup inside the heat exchanger, or a venting or exhaust problem. Start by noting any code shown, attempt a soft reset, then work through the flow and vent checks before calling a technician.

NoritzWaterheaterSeverity: moderate70% DIY Success

Time to Fix

15–60 min

Difficulty

beginner

Parts Cost

—

Tools Needed

Flashlight, Adjustable wrench

Wrong code?

Not seeing TROUBLESHOOTING on your display?

Select what your appliance is actually doing and we'll take you to the right guide.

error code on display

HUB

no ignition

flame lost during use

no hot water

NO-HOT-WATER

error code on display

RESET

What Does the TROUBLESHOOTING Code Mean?

Covers the 8 most common Noritz water heater problems. If an error code is shown, go to the specific code article. If no code is shown, use the symptom sections here.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Active error code requiring specific repair40%

Water flow rate below 0.5 GPM activation threshold24%

Scale buildup reducing heat exchanger efficiency14%

Gas supply interrupted or pressure too low12%

Blocked or recirculating exhaust vent10%

Symptoms You May Notice

No hot water at all
Water lukewarm but not hot
Hot water alternates between hot and cold
Unit will not ignite
Error code on display
Unit shuts off mid-use
Unusual noise from unit
Water dripping from unit exterior

Can you reset a Noritz waterheater to clear the TROUBLESHOOTING code?

Soft reset: press the power button to turn the unit off, wait 30 seconds, then press again. Hard reset: disconnect power at the unit or breaker for 60 seconds. Code 14 (thermal fuse) cannot be cleared by reset and requires a service call.

Tools Required for Diagnosis

FlashlightAdjustable wrenchMultimeterFlow meter or bucket and timer

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Check the controller display for any numeric error code

Check the controller display for any numeric error code. If a code is shown, write it down and navigate to the specific code repair guide.

Perform a soft reset

Measure water flow at the tap

Verify the gas supply

Inspect the exterior vent termination

Frequently Asked Questions

Why does my Noritz water heater click but not ignite?

Clicking is the igniter sparking. If the unit clicks repeatedly but no flame appears, the most common causes are a dirty or corroded flame rod, insufficient gas pressure, or gas supply that is off. Check Code 11 for the full repair sequence.

Why does hot water go cold then hot again in my Noritz?

This is called the cold water sandwich effect. It happens when a short hot water draw ends, leaving hot water in the pipes. When the next draw starts, you feel: residual hot water in pipes, then the unheated cold water that entered after the last draw, then newly heated water. Installing a recirculation pump or pre-flushing briefly minimizes it.

How often should a Noritz tankless water heater be serviced?

Noritz recommends annual inspection and descaling in hard water areas (above 11 gpg). In soft water areas, a 2-year interval is common. Skipping descaling is the leading cause of Code 29 and Code 14 faults.

My Noritz runs fine for a few minutes then shuts off. What causes that?

Mid-cycle shutoff is usually caused by the heat exchanger overheating from scale buildup (Code 29) or a flame rod that fails when hot (Code 12). Enter service mode and check stored error history to identify the code.

Can I troubleshoot a Noritz water heater myself or do I need a plumber?

Many beginner-level fixes are safe for homeowners: resetting the unit, cleaning intake screens, checking gas supply, and clearing vent blockages. Flame rod cleaning and descaling require basic tools and intermediate skills. Gas valve replacement, thermal fuse replacement (Code 14), and fan motor repair should be handled by a licensed plumber or Noritz service technician.

Related Noritz Waterheater Error Codes

Code: HUBNoritz Tankless Water Heater Error Codes: Complete NR and NRCP Series Guide Code: 11Noritz Code 11: No Ignition Fix for NR and NRCP Series Code: 12Noritz Code 12: Flame Failure During Operation Code: NO-HOT-WATERNoritz Tankless Water Heater No Hot Water: 7 Causes and How to Fix Them Code: RESETHow to Reset a Noritz Tankless Water Heater and Clear Error Codes

Models Known to Experience TROUBLESHOOTING Errors

This repair applies to most Noritz waterheaters with this error code. Common model numbers include:

NRCP199-DV, NRCP111-DV, NR98-DV, NR66-DV, NR711

Last verified for technical accuracy on March 14, 2026