Navien Water Heater Error Code 024: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
024
Brand
Navien
Product Type
water_heater
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code 024 on your Navien tankless water heater indicates a mixing valve fault. The mixing valve regulates water temperature by blending hot and cold water; when faulty, it can cause temperature fluctuations or no hot water. This guide will help you diagnose and fix the issue, often by cleaning or replacing the mixing valve.
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Tools You'll Need

How to Fix Error Code 024

  1. Turn Off Power and Water Supply

    Always turn off power and gas before servicing to prevent electrical shock or burns.

  2. Access the Mixing Valve

  3. Inspect and Clean the Mixing Valve

    Do not use force or sharp tools that could damage the valve.

  4. Check Electrical Connections

    Work carefully around electrical components even with power off.

  5. Restore Power and Test

    Monitor for leaks during startup.

  6. Replace Mixing Valve (if needed)

    Ensure the replacement part matches your unit's specifications.

Parts You May Need

Mixing valve assembly
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Mixing valve assembly
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Mixing valve assembly
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Mixing valve assembly
Check Price on Amazon
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When to Call a Professional

If error persists after cleaning and replacing the mixing valve, or if you are uncomfortable working with gas lines or electrical components, contact a qualified Navien technician.

Frequently Asked Questions

What does Navien error code 024 mean?
Error code 024 indicates a mixing valve fault in your Navien tankless water heater. The mixing valve blends hot and cold water to maintain a stable output temperature. A fault can cause temperature fluctuations or shutdown.
Can I bypass the mixing valve to fix error 024?
Bypassing is not recommended as it may cause scalding or damage the unit. The mixing valve is a safety feature. Proper repair or replacement is advised.
How much does it cost to replace a Navien mixing valve?
The mixing valve part typically costs $50-$150 depending on your model. Professional installation can add $100-$200. DIY replacement saves labor costs.
Will error 024 clear itself after a reset?
Sometimes a power cycle (turning off the unit for 5 minutes) can clear temporary faults, but if the hardware issue persists, the error will return.
Does error 024 affect gas or electric models?
Error 024 is specific to Navien tankless water heaters, which are gas-powered. Electric models may have different error codes.

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