Navien NPE-240A2 adding external recirculation valve

[Art96142]

My NPE-240A2 was installed in June 2022 with a recirculation line. Unit ran fine for seven months until the internal check valve failed in February 2023. With a bit of difficulty I was able to obtain two replacement check valves (the check valve part number for the newer NPE units is #30024442A, the old part number is still listed in the installation manual). The unit is now running properly.

My question is this. Is there any reason why I could not install a check valve in the recirculation return line just before the heater (properly oriented) to replace the internal valve? A look at the flow diagram in the installation manual seems to indicate that this is possible. I was able to disassemble the original stuck check valve so I could reinstall the valve body with the internal check valve portion removed (the small section at the end of the valve body containing the check valve with spring can be unsnapped with a couple of jeweler screwdrivers). I expect that the newly installed Navien check valve will also fail in time - probably as an effect of how the local water is treated - damaging the valve O ring (EPDM?). The proper Navien check valve isn’t expensive but not that easy to obtain and if it continues to fail the cost and hassle adds up. I understand that this would void the warranty but as I installed the original unit myself this is a moot point.

BTW, it was this forum that helped me solve the original problem.

Thank you for your suggestions,

Art

 

[John Gayewski]

We install external check valves on all of our navien's.

 

[Sponsor]

 

[Art96142]

John,

Thank you for confirming what I suspected to be the case. An external check valve is easily installed.

For those of you reading this thread later the external check valve placed in the recirculating line close to the heater must be oriented so the flow direction is towards the water heater and the heater must be setup for external recirculation. Most likely you already know this but I want to make it very clear so no one has a problem.


Art

 

[DenverSam]

Art, I'm considering removing the body of the internal check and adding the external check as you describe. Do you think this will be more of a permanent fix? thanks.

 

[Art96142]

Sam,

Yes I do believe that using an external check valve is a more permanent fix as John indicated earlier in this thread. The replacement external check valve while not inside in the heater is in the same part of the plumbing “circuit.” Just make sure to install the new valve in the correct direction. Think of it like a diode in a circuit and you will see how it works.

Art

 

[DenverSam]

Came back to report that my internal check valves failed again after only 5 months or so. I gutted them and installed Webstone serviceable check valves.

Webstone PEX-108XW 1/2" Low Pressure Spring Check Valve H-10832W​

Webstone PEX-108XW 1/2" Low Pressure Spring Check Valve H-10832W

Webstone forged DZR brass in-line spring check valve that features an easily serviceable design with dual union ends, stainless steel spring, and soft seat. Easily control flow with this Webstone valve. Designed for use with water, oil, and glycol mix in residential or commercial plumbing and...

libertysupply.com

 

[DenverSam]

Bumping this thread because it seems that everyone still has issues with the revised internal Navien check valve. DHW issues, temperature issues, etc.

14 months later and my external check valve is working great. I've had zero issues with my Navien NPW-240A2 since. Prior I had hot water coming out of cold faucets. Cold water coming out of hot faucets. Lukewarm water in showers. Water temps that drastically changed during a shower.

A few other tips for the homeowner DIY types and troubleshooters:
1. Gut the internal check valve and install an external one as per this thread.
2. Check the plumbing on your unit against the specifications in the Navien installation manual. My cascading system with external recirc line (installed by "professionals") was NOT plumbed properly. I was missing the check valve and expansion tank on the cold supply line (page 26 of the manual. Shown again on pages 31, 70, 139.). Many "pros" and most city inspectors do not know and do not bother to look at a manual.
3. Stop telling Navien support you're a homeowner. Tell them you're with Jim-Bob Plumbing. They don't check anything. If they could produce a quality o-ring they'd have fewer homeowners calling them.
4. If your plumbing is all pex just buy yourself the Milwuakee M12 pex tool. It'll pay for itself and then some in just one job (like the above fixes).