Hello, everyone! Joseph here, and today we’re diving into a vital maintenance task for your Navien tankless water heater: diagnosing, troubleshooting, and replacing the internal check valve. This guide will focus specifically on the NPE and few NHW models, which has an internal pump but does not come with a dedicated return line or internal buffer tank. In this models an internal check valve is present to avoid mixing cold and hot lines. So please read till end so that you can understand everything from the symptoms of a malfunctioning check valve to safely removing and replacing it.
What is a Check Valve and Why is It Important?
The check valve in a Navien NPE tankless water heater is essential for preventing backflow, ensuring hot water only flows in the intended direction. In systems with external or dedicated pumps, the check valve stops cold water from contaminating hot water lines, preserving temperature stability and system efficiency. Over time, mineral buildup or other issues can cause the check valve to malfunction, disrupting the flow of hot water.
The part number for Navien NPE check value is 30024442A.
Symptoms of a Failing Check Valve in Navien heater
A malfunctioning check valve often reveals itself through inconsistent water temperatures. You may notice:
- Hot water starts flowing but quickly turns lukewarm or cold.
- Intermittent temperature drops while the hot water is in use.
- System diagnostics indicate a low outgoing water temperature (around 75°-78°F).
These symptoms suggest the check valve isn’t functioning correctly and may need replacement.
How to Diagnose Check Valve Issues in Your Navien Tankless Water Heater
To confirm a faulty check valve, use the unit’s diagnostic tools:
- Access the controller manual for guidance on checking outgoing water temperatures.
- If you observe an abnormally low temperature in the diagnostics, this likely confirms a check valve issue.
Step-by-Step Guide to Check Valve Replacement
1. Locate the Check Valve
- First, locate the internal and external circulation valve inside the polymer housing near the pump.
- Navien typically marks the check valve with a small red indicator for easy identification.
2. Remove the Check Valve
- Using needle-nose pliers, gently turn and wiggle the check valve. It should require less than a quarter-turn to dislodge.
- Carefully pull it out to avoid damaging the internal components.
3. Inspect and Clean the Check Valve (Temporary Fix)
- If a replacement check valve isn’t immediately available, you can perform an emergency fix:
- Boil a small amount of water and dilute it with water.
- Submerge the check valve in the warm vinegar solution to loosen any mineral buildup.
- Note: This is a temporary fix, and it’s best to replace the check valve as soon as possible for optimal performance.
4. Install the New Check Valve
- Get a check valve with part number 30024442A for your NPE A2 unit.
- Ensure the new check valve is pre-lubricated with heatproof grease on the O-rings.
- Align the notches on the check valve with those inside the unit and twist it into place.
5. Check for Proper Installation
- Use needle-nose pliers to ensure the internal and external circulation valve is in the correct position, which will allow for smooth operation.
- Run a final diagnostic check to confirm the system is heating water to the proper temperature.
Proactive Maintenance Tips to Prevent Check Valve Issues
Routine maintenance can help extend the life of your tankless water heater:
- Annual Descaling: Hard water deposits can accumulate over time. Descale the unit at least once a year using a vinegar solution or professional-grade descaling solution.
- Regular Filter Checks: Both the cold water inlet screen and pump screen should be removed, cleaned, and checked for damage during each service visit. These screens prevent debris from entering the system and causing buildup.
- Dedicated Return Line Management: For larger homes or high-demand setups, consider an external pump with a spring-loaded check valve to maintain sufficient water pressure and flow rate across the system.
When to Consider an External Pump
For larger installations or homes with extended plumbing systems, the Navien NPE model may need extra assistance from an external pump to deliver adequate GPM (gallons per minute). Adding an external pump with a spring-loaded check valve can prevent clogging more effectively than a traditional clapper valve.
Troubleshooting and Diagnosing Over the Phone
If you’re troubleshooting for someone else, ask the customer about the age of their unit and describe the symptoms. Units that are 4-5 years old may have increased buildup, so you may need to bring a replacement check valve if mineral deposits have caused significant clogging.
