Navien NPE-240A2 error code 515-09

[Art96142]

Ever since I installed my Navien 240A2 I have had a small but annoying issue with random shut downs of the heater with the diplay reading error code 515-09 “abnormal pcb.“ The unit may go a couple of weeks without an issue and then suddenly cutout twice in three days. Fortunately, resetting the unit restores proper operation. However, having the unit shut down at random intervals is not what I expected when I had the Navien tankless heater installed. My first thought to address the issue was to install an AC line filter thinking that line or ground noise may be triggering a fault but the random shutdowns continued. After my experience with contacting Navien on another issue I was reluctant to call them again especially since my problem seemed more of an electrical/electronic issue than a plumbing one. Then I came across a couple of you tube videos relating to the Navien tankless heaters. In the first video, a plumbing contractor in San Diego takes Navien to task for the number of warranty calls he is making on Navien heaters. The video did not go into exact detail as to what was prompting the number of repair calls but from what I saw it looked very similar to the issue I was experiencing. Next I found a short video clip of a plumber using a newly supplied device from Navien to reflash the software in the Navien heaters. That definitely led me to believe that the issue I was having was firmware related. I thought about asking a plumber to reflash my unit but then realized that Navien must have fixed this issue for newly manufactured units. I found a replacement main pcb for online an excellent price. Navien has issued a new part number for the pcb, #30027274B, which indicates that Navien recognized the problem and addressed it. On the box containing the new pcb the label has the listing “PCB (GWC303-6M) V12-2“ in addition to the part number. It takes about twenty minutes to replace the pcb and there are a number of you tube videos showing how it is done. It has been a month and half since I replaced the pcb and I have not experienced any further problems. I have not seen many comments regarding this problem online so it may not be that widespread an issue. But if you are having a similar issue I hope that my experience will help you resolve it.

Art

 

[Breplum]

We have many PCBs to replace when the 240A2s came out. They are always covered since the units are all covered under Navien's warranty, including good labor paid to plumbers when under 1 year old.
I do think that they fixed that bad PCB issue.
Now the major ongoing issue is with dedicated recirc, the check valves get stuck open and have to be replaced or I've found that a #56008 o-ring in the drawers at the hardware store can be replaced on the check valve but it is a bit tricky to get the check-valve taken apart.

 

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[Art96142]

I had to deal with the recirc check valve issue as well. I ordered a couple of replacement check valves (#30024442) for about $5 each. I installed the new check valve nine months ago and so far it has been working well. I managed to disassemble the original check valve and will try out using a #69 o-ring. Thank you, Breplum - I appreciate finding out the o-ring size as it is difficult to estimate by eye alone.

Art

 

[Breplum]

Actually, forget that o ring number. In my head I saw the price and inserted the number wrongly. at the drawers of the hardware store it is No. 56008 7/16" x 9/16" 1/16" Body Dia. cost is $.69

 

[Art96142]

Breplum, thanks for the update on the o-ring. You have helped many people on this forum and I am sure all of us appreciate your wisdom and experience.

Art

 

[rahul]

Thank you for the this post. What was your model number of heater ? Was it 240 A NG or something else ?