Noritz Code 14: Thermal Fuse Blown - Overheating Fault

Quick Answer

Noritz Code 14 means the thermal fuse has blown. This is a one-time safety cutoff that trips when the heat exchanger reaches a dangerously high temperature. The fuse cannot be reset - it must be replaced. In almost all cases, the root cause is scale buildup on the heat exchanger walls, which insulates the water from absorbing heat properly and causes the metal to overheat. Simply replacing the fuse without descaling the heat exchanger will result in the fuse blowing again within months. Code 14 always requires a professional service call.

NoritzWaterheaterSeverity: criticalDifficulty: advanced85% DIY Success

Time to Fix

90–240 min

Difficulty

advanced

Parts Cost

$0 – $30

Tools Needed

Phillips screwdriver, Adjustable wrench

Wrong code?

Not seeing 14 on your display?

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

error code on display

HUB

heat exchanger overtemp

error code on display

RESET

What Does the 14 Code Mean?

One-time thermal fuse has blown from overheating. Must be replaced by a technician. Root cause is almost always scale buildup - descaling is required alongside fuse replacement.

Most Likely Causes

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

Scale buildup on heat exchanger reducing water-side heat absorption40%

Chronically low water flow rate causing localized overheating24%

Thermal fuse component failure (rare without another underlying cause)22%

Inaccurate flow sensor reporting false flow to control board14%

Symptoms You May Notice

Code 14 on controller display
No hot water - unit will not start
Code 14 may have been preceded by Code 29 (overtemp warning)
Unit completely non-functional after reset attempts

Can you reset a Noritz waterheater to clear the 14 code?

Code 14 cannot be cleared by reset. The thermal fuse is a one-time safety device that physically opens when it blows. A reset will not restore function. A licensed technician must replace the fuse and address the root cause (scale buildup) before the unit will operate.

Tools Required for Diagnosis

Phillips screwdriverAdjustable wrenchSubmersible pump (for descaling flush)5-gallon bucketVinyl tubing

Diagnostic Checklist

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

Attempt a soft reset

Attempt a soft reset: power off for 30 seconds, then power on. If Code 14 returns immediately or the unit does not start, the thermal fuse is confirmed blown.

Check the unit's service history

While awaiting service

The technician will access the heat exchanger, replace the

After repair

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
Thermal Fuse100169765 · $8–$20	100169765	$8 – $20
Descaling Service Kit (Vinegar Flush)N/A - service procedure · $0–$30	N/A - service procedure	$0 – $30
Inlet Filter Screen100113571 · $5–$15	100113571	$5 – $15

Verify part fitment for your Noritz model

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs

Labor Approach

Our Verdict

REPAIR

Estimated Cost: $15 (Parts) vs $1150 (New Machine)

Frequently Asked Questions

Can I reset Noritz Code 14 myself?

No. Code 14 is triggered by a physical thermal fuse that has burned open. Pressing the reset button will not restore the circuit. The fuse must be replaced by a technician. This is by design - it prevents the unit from running in a condition that previously reached unsafe temperatures.

How much does it cost to fix Noritz Code 14?

Expect to pay $150 to $350 for the service call, fuse replacement, and a basic descaling flush combined. If the heat exchanger has been severely damaged by repeated overheating, a heat exchanger replacement can cost $400 to $700 in parts alone.

Why did my Noritz Code 14 come back after the fuse was replaced?

If the thermal fuse blows again shortly after replacement, the heat exchanger was not fully descaled during the repair, or there is a low water flow condition that was not corrected. The new fuse will blow under the same overheating conditions unless the root cause is fixed.

Is Code 14 the same as Code 29 on a Noritz?

They are related but different. Code 29 is a recoverable high-limit overtemp fault - the unit shuts down but the safety device is not consumed. Code 14 means the thermal fuse actually blew. Code 29 is often a warning that Code 14 is coming if the scale issue is not resolved.

How can I prevent Code 14 on my Noritz?

Annual descaling is the primary prevention. In hard water areas (above 11 GPG hardness), descale every 12 months. In soft water, every 2 years is typical. Installing a whole-house water softener or a dedicated tankless water heater scale inhibitor filter significantly extends the interval.

Related Noritz Waterheater Error Codes

Code: HUBNoritz Tankless Water Heater Error Codes: Complete NR and NRCP Series Guide Code: 29Noritz Code 29: Heat Exchanger High Limit Exceeded Code: RESETHow to Reset a Noritz Tankless Water Heater and Clear Error Codes

Models Known to Experience 14 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