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Navien CH240 Error 035E / bad HE gasket

giantsean Member Posts: 65
Hey All,

Long time no post. I still have an original vintage 2012 Navien CH240 which has already been replaced once (in 2015) for a dripping heat exchanger. Yesterday it started throwing Error 35 (gas pressure sensor) pretty regularly, though it has calmed down somewhat and will run longer at lower DHW temps before the error kicks in. It is definitely on it's last legs, having had several parts replaced (most recently the 3 way valve and pump). At one point I discovered a mystery air leak while the cover was off... today while cycling it several times I found out why. The top gasket between the burner box and the heat exchanger assembly is pretty much non-existent in one corner (ie, I can see the flame through it, with a nice touch of CO blowing out :smiley: ). I know Navien has a 10 year warranty on the HE's (which for me expires at the end of 2022). Any idea if they will warranty a clearly sub-optimal situation such as this?

I am guessing the gas pressure error is being somehow caused by the bad sealing, but I'm not that saavy so that's just an ASSumption. If it's covered it may not matter, but still curious. Thanks for any advice!


  • mattyc
    mattyc Member Posts: 42
    I would start off by calling tech support before changing any parts. Mention the exhaust leak first (as that is a more critical issue), along with the error codes that you are getting. Their tech support is very helpful.
    They will be able to tell you if it is under warranty or not. If it is, you still may be in luck but if not, may be time to consider a replacement in my opinion. That model is outdated at this point unfortunately.
    EBEBRATT-Ed Member Posts: 13,149
    Navien knows all about those problems. Google it it's all over you tube. I would definitely call Navien.
  • giantsean
    giantsean Member Posts: 65
    Per my guy they will warranty replace it with an NCB240-130H. I noticed the space heating BTU specs are a bit less on this model... is this all mostly paper engineering at this point?
  • mattmia2
    mattmia2 Member Posts: 7,207
    is your space heating load anywhere close to the space heating capacity anyhow?
  • giantsean
    giantsean Member Posts: 65
    It's two air handlers good for about 95K combined. The CH-240 was able to deliver them both 185 degree water (if needed) pretty easily, but that was only needed on really cold days. I think the NCB240/130 is good for 120 so on paper I'm ok, but not sure if there is a real life difference