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Condensation inside Navien tankless water heater

cannibalflea Member Posts: 7
edited September 2021 in Domestic Hot Water
Hi everyone,
My parents had Navien tankless water heater installed at their home about seven years ago. Every time I am in town (if I remember) I will try and do some basic maintenance on the unit, including open it up clean the filter and interior of the cabinet. They don't have hard water, so I've only done a flush once about two years ago.
When I opened the cabinet earlier today, I noticed some brown stains at various locations inside the cabinet. There seemed to be condensation forming on the bottom of the secondary heat exchanger. When I tried to clean it, it seemed to be a brown oily substance:

I tried my best to clean the condensation and any of the stains I could get to. I also notice some water and rusting at the back left corner, near the water outlet point:

I also noticed a lot of rust around the flue exhaust:

I tried to clean up as best as I could but wasn't sure what this was about. I also looked at the air intake filter and noticed a lot of debris (there has been some construction next door which I think made things worse).
I also noticed some green rust around the igniter on the primary heat exchanger:

While I looking online it seems at least one other person had a similar issue on reddit. Some of the comments suggested that exhaust gas is recirculating into the cabinet. Another suggestion was the gasket of the exhaust packing ring isn’t rated to handle the temperature of the exhaust gases (link to a video which unfortunately is private). There was also a reference to a post on HeatingHelp which seemed to suggest the issue might be an issue at the concentric termination (which I haven't yet checked).

I was wondering if there were any thoughts on what might be the issue. Can this be just due to debris in the air intake filter or is this something more serious? Do you think I should be contact Navien to get their diagnosis?


    EBEBRATT-Ed Member Posts: 11,996
    Yes, contact Navien send them pictures you have an issue
  • stever1000
    stever1000 Member Posts: 30
    Look up pipe doctor on YouTube,  you wills see why that is happening.  
  • stever1000
    stever1000 Member Posts: 30
    You can join his class action lawsuit also. Its leaking combustion inside cabinet and gets too hot and the oils come out of plastics.
  • cannibalflea
    cannibalflea Member Posts: 7
    Thanks for the feedback. I will contact Navien tomorrow. Is it still okay to keep the system on or is there a safety risk?
    EBEBRATT-Ed Member Posts: 11,996

    Can't say for sure I don't have direct experience but from what I have herd some have had carbon monoxide issues
  • SuperTech
    SuperTech Member Posts: 1,792
    I have a lot of experience with this problem and yours looks to be an exhaust packing ring combined with the heat exchanger or heat exchanger gasket leaking.  Navien water heaters boilers notorious for these problems.  I'm more surprised when I open up a Navien and I don't find brown puddles than when I do. 9/10 will have this going on. 

    Don't expect any help from Navien, they won't provide any.  I would encourage you to join the class action lawsuit and replace that Navien as soon as possible.  My professional opinion is that any appliance that leaks carbon monoxide should be replaced  
  • stever1000
    stever1000 Member Posts: 30
    Make sure you have a carbon monoxide detector close and keep cover on navien.  Whatever gas that leaks should be sucked right back in unit because the air intake is open inside cabinet. But keep eye on co detector.  
  • rick in Alaska
    rick in Alaska Member Posts: 1,362
    Hm. Just looked at one today and had the same issue of the oily residue. I thought it was really weird, but did not find a reason for it. Looks like I need to do a little more research on this now.
    Thanks for bringing this up though. Now I have a direction to go.
  • neilc
    neilc Member Posts: 1,804
    look up mikey pipes on you tube, or navien leaks on u tube
    known to beat dead horses