Navien NPE-240A going cold in showers - check valve issue?

Discussion in 'Tankless Water Heater Forum' started by glycoski, Jun 10, 2020.

  1. glycoski

    glycoski New Member

    Jun 10, 2020
    ISSUE: I've recently been having an issue with my Navien NPE-240A sending cold water to my shower after about 4 or 5 minutes. When I first start the shower, the temperature is hot as usual (setpoint at 125 degrees), then a few minutes later, the temperature drops considerably to luke-warm or cool (but not entirely cold). My children have commented that the same is happening in their showers as well at other locations in the house, so that tells me it is not an issue with just my shower's mixing valve.

    INTERVENTIONS: I've been keeping up with the regular maintenance on the Navien as far as yearly flushing, screen cleaning, and vent clearing. A check of these maintenance targets revealed no possible cause for the drop in temperature that I'm seeing.

    I called Navien Customer Service to see if they could help. The rep sort of blew me off telling me that I wouldn't be able to address the issue myself and that I would need to call in a certified Navien Service Technician. He started spewing out that the Venturi probably needs to be assessed and that I'd need to hook up manometers upstream and downstream, possible igniter issues, etc. - things only a certified technician would be able to fix. To be honest, I found him to be condescending and rude. I don't accept that.

    FIX: So, I found the same issue here on this site (thanks mitch22 and HydroAir Joe!). I pulled the check valve out and found that the spring had become mis-aligned and there were a few flecks of dirt around the sealing ring. A quick cleaning with a toothbrush and re-alignment of the spring seems to have done the trick! Now, an 11-minute procedure has my Navien performing as it had been for the previous five years with essentially endless hot water!

    FOLLOW-UP: I have a question...are these check valves so delicate that they should not really be handled very often? I was planning on adding a check valve assessment to my yearly maintenance tasks, but the spring seems fragile and Navien doesn't detail this as part of their maintenance routine. Does anyone see any issues with pulling and servicing the check valve each year?
  2. WorthFlorida

    WorthFlorida The wife is still training me.

    Oct 28, 2009
    Orlando, Florida
    Thanks for your info on the fix. I cannot answer your question, but the problem with companies like Navien is liability. If a service center tells someone how to fix things and that person gets injured, guess what happens? However, the attitude shown show never be especially since you have a good understanding on the unit and seem competent. On this forum I have several times had made similar statements because of the type of questions asked, the person had no idea what he was doing. I don't want someone to electrocute themselves. :)
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  4. AMC-NYC

    AMC-NYC New Member

    Dec 5, 2020
    I developed this issue as well on my NPE-240A that was installed in 2017 so I got only 3.5 years before failure. I received the same response from the customer service line which was really irritating. I understand liability concerns but instead of stating this is a company policy due to liability concerns, which I would be totally fine with, the rep was condescending and gave the example of dishwasher issue which I promptly told him I would repair it myself. They should not assume everyone that calls is totally helpless and stupid. I have done installs and repairs on my house much better that "professionals" as I take the extra time and $ to make sure it will last. Most service people today are in it for the quick fix which usually turns out to be a patch job that ends up failing again so I have very little faith. Not to mention their cost.

    Should anyone else have this issue and find this thread, this is the link for the original fix thread.
    S. H. likes this.
  5. breplum

    breplum Member

    Oct 2, 2004
    Plumbing and heating contractor
    San Francisco Bay Area
    I only work on Navien brand tankless now that I am in semi-retirement. So, I get my hands on a lot of the NPEs
    Too bad that Navien won't help enterprising customers like you but they seem to have this "policy" of pushing professional repair when so much could be done by non-techs like yourself. It is understandable from a liability perspective like WorthFlorida surmises.
    And to run through the tech testing steps with a homeowner would take a lot more of the tech desk reps than they want to spend.

    Those check valves sticking are definitely a problem that I run into VERY often, even, sometimes in less than a year, especially with dedicated recirculation systems.
    We have chloramine as the primary disinfectant in our water supply and that may be a factor on o-ring deterioration.

    If unit is less than 6yrs old, I do recommend calling Navien and requesting a replacement check valve indicating how you "temporarily" fixed the issue but would like a pristine part.
    Last edited: Dec 5, 2020
  6. wmills01

    wmills01 New Member

    Dec 21, 2020
    I talked directly with Navien tech about the recirculation not working. He said the check valve downstream of the recirculation pump should be replaced yearly. I replaced it, descaled the whole system and it now works as it is supposed to. Supplies Depot sells the check valves for about $4.00. I bought a couple and will replace them yearly when I descale the unit.
  7. Corrina

    Corrina New Member

    Mar 15, 2021
    Santa Cruz
    @breplum I have a question for you.

    I have done lots of research on this and know more than my plumber at this point. I called Navien Tech Support who asked to speak to "a guy" so to avoid losing it with that company for a sexist comment I'd like to solve this myself with some help on the forum.

    I have a Navien 240A. My original installer set the recirc tank to external and the dial is in the 6:00 position. The second dipswitch tab on the control panel is up, all others down. Its about 6 years old and was working up until last week. All showers (hansgrohe) are starting cold, get hot, then go to lukewarm. The bathtub (Grohe single handle) is about lukewarm.

    I've cleaned all filters of the Navien with the same result. I'm getting set to order from Supplies Depot:

    Anything else you can suggest? I've watched every Youtube video I can watch and all signs lead to Check Valve issues.
  8. Bannerman

    Bannerman Well-Known Member

    Mar 19, 2014
    Ontario, Canada
    Is your home equipped with a recirculation return line? If there is no recirc line connected to the Recirculation Inlet fitting, then the recirculation settings should be set to INTERNAL (2-way valve & 1st dipswitch ON and all others OFF).

    Most often, regular White Vinegar and water are used as a descaling solution as opposed to buying a speciality chemical.

    The 240A manual I viewed on page #90, shows the Check-Valve as part# 90008359B. Perhaps due to the frequent failures, Navien has since altered the check-valve design and assigned a new part number. Suggest asking Supplies Depot to verify.
  9. breplum

    breplum Member

    Oct 2, 2004
    Plumbing and heating contractor
    San Francisco Bay Area
    Yes, the check valve in your link will typically do the trick (at six years, Navien should send you a covered replacement), if you first check to make sure you don't have a crossover leak between the hot and cold. To do that, turn the power off on your unit, then turn the cold water supply valve off at the Navien, then go in the house and open a dedicated hot tap and make sure the water flow stops.
    I use the Descaler fluid when it has been so many years, as is your case. I don't know about your water quality, but if the water is good, then indeed, white vinegar for descaling annually is fine.
    You know, you need a clean pump and two washing machine type hoses and a bucket to do the descale.
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