Help, water is hot then cold then hot....and then e003

Discussion in 'Tankless Water Heater Forum' started by unagi, Mar 24, 2021.

  1. unagi

    unagi New Member

    Joined:
    Mar 24, 2021
    Location:
    Boston, MA
    I hope someone can help with real advice. Tech support at Navien just wants me to call my plumber so he can call them. For the last 3 years, the shower has been hot, then cold then hot again. It happens after about 10 minutes into the shower. Navien says it's the mixing valve in the shower or somewhere in the house that's making this happen. I can't replace every one, but have some and this does not fix it. In the last 2 weeks, I have had cold water to start, sometimes the e003 error. After a power shutdown and wait 5 minutes, it's fine, still get the hot and cold things happening. Its a combi, NG and we have 4 zones of baseboard hot water heat. The run is not that far from the boiler and the house is only 1600 sq. ft. Any ideas? Pressure valve? Control board?
     
  2. automaton

    automaton I just like reading manuals

    Joined:
    Mar 7, 2021
    Location:
    New England
    How old is it? Ever had the ignition rods/element replaced? If e003 happens often, could be that - about a $15 part. Otherwise, could be the infamous 3 way valve that redirects heating water to the DHW plate exchanger.
    How I would troubleshoot the valve: open a high flow hot faucet and watch the boiler. Does it stay lit? Does it keep firing at a constant rate or does it sound like it's ramping up then down? Does the space heating temp go way up, then down when the boiler backs off? Is the space heating loop warm/hot to the touch (shouldn't be if heat is off). If the valve is stuck, not enough heating water is making it to the exchanger so the boiler would be compensating by firing up.
    My Navien (which needs a good flushing) needs space heating temp of 135F to make 120F temp for my wife's showers.
     
    Last edited: Mar 24, 2021
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  4. fitter30

    fitter30 Well-Known Member

    Joined:
    Feb 2, 2020
    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    Code is flame failure ,whats the model number and does it have recirculation .
     
  5. unagi

    unagi New Member

    Joined:
    Mar 24, 2021
    Location:
    Boston, MA
    It's a few years old, maybe 5. NCB 240 NG. I believe it has recirculation. I did the troubleshooting again today, open DHW, flame icon stays lit, psi goes up and down 14.9-16. Temp stayed at 149 f. This was for the kitchen sink. Next test where the cold fluctuates, is the shower, I will record on my phone for 15 minutes and report. As far as I can tell (its hard) there is no fluctuations of temp for heating. This morning we had the e003 error when I woke up and went to grab a shower. This is getting silly if we have cold water to start every 2 days. The loop is supposed to keep it warm so it doesn't take too long to warm up, that seems to be taking cold for longer now.
     
  6. fitter30

    fitter30 Well-Known Member

    Joined:
    Feb 2, 2020
    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    Last edited: Apr 1, 2021
  7. unagi

    unagi New Member

    Joined:
    Mar 24, 2021
    Location:
    Boston, MA
  8. fitter30

    fitter30 Well-Known Member

    Joined:
    Feb 2, 2020
    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    1. E003 doesn't trip till after 10 failures look at the pic in previous post. So they will try to refire.
     
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