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one room suddenly stopped working

Hello all, and thank you for reading. I have a radiant floor heating system in my new home . 3 stories, 2900 sqF, and using a Navien Boiler and Taco controllers. There are 6 zones, and one zone does not work suddenly. I replaced all thermostats with NEST , and it worked fine. I had the system service and it worked fine. Then it stopped about 2 weeks after the service call as described above. Also, this am , the boiler basically stopped working and the word " AIR" flashed. I reset the boiler and all is well. Please help!


  • Jamie Hall
    Jamie Hall Member Posts: 17,102
    Nice of the boiler to tell you what the problem is... somehow you have gotten air into the system, and it will need to be purged.
    Which doesn't answer how the air got in there. What pressure does the system run at? Is the expansion tank in the right place (just before the inlet to the circulating pump(s)? Is there an air eliminator? Is it working?

    Is there a leak...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SuperTech
    SuperTech Member Posts: 1,689
    Can you post pictures of the boiler and the near boiler piping? It's possible that the installer may have used non O2 barrier PEX. I have seen that a few times this year.
  • Kash101
    Kash101 Member Posts: 3
    let me know if this is helpful and thank you !
  • Kash101
    Kash101 Member Posts: 3
    So , it’s so strange. The unit rest once I unplugged it.

    Then last night I was sleeping downstairs in the guest room ( pregnant wife needed her space !) and all was well. Then I smelled a burning smell (almost like burning plastic ) and then a loud POP , I turned all the floor heaters off. Went to check the unit and see attached video.

    The pressure was way down ( 8 psi ) and the temp was going down , to 107 from 114 and counting. Went back to bed and this morning all was working again.
  • neilc
    neilc Member Posts: 1,465
    could you post one or 2 wide shots showing all those closeups ?
    one or 2 showing everything together.
  • Keifer301
    Keifer301 Member Posts: 7
    Boiler water pressure is too low and this can cause poor circulation to all zones (no heat) and popping noises from the heat exchanger when the boiler is running (not enough water flow past the heat exchanger when its firing).
    Navien has been known for this problem so I have had to install an external " boiler feed water pressure regulator" to correct these problems.
    Loving the fact to be known as an old timer and seeing the changes I have seen.