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Plugged Tankless Coil

Rich_L Member Posts: 81
edited March 2016 in Domestic Hot Water
I have two Ruud tankless domestic water heater in a building I just inherited to take care of. The two units are piped in parallel. I've found one of the units to have a completely plugged coil. I get absolutely no flow, even with city pressure against it. I've tried pumping cleaning solution through it, from both directions, but with no flow I can't get anywhere. Can this unit be saved? So far I've tried DHW Tankless cleaner and ice machine cleaner. I've been trying to get flow with cleaning solution for over a week now. Thanks


  • Leon82
    Leon82 Member Posts: 684
    Remove the heat exchanger and soak in vinagar or heavier chemical for a few days?
  • kcopp
    kcopp Member Posts: 4,443
    The HX is pretty thin in most of those units. Instead of going through all this "cleaning" I would just replace the HX.
    Then find out why it did that and take action so it does not happen again.
    They do make siliphos filters that allow the calcium to not stick to the piping.

  • Jamie Hall
    Jamie Hall Member Posts: 23,438
    @kcopp has an excellent point. If it's that badly plugged, the odds of its leaking when you get the scale out of it are close to 100%.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Rich_L
    Rich_L Member Posts: 81
    Thanks for the responses. I didn't know if possibly anyone else had such experiences with these units. I believe what led to this is simply lack of attention/ maintenance. When I asked what kind of schedule they had for descaling their tankless water heaters I was met with a puzzled glare... This unit is almost six years old and has never been de-scaled! Thanks again
  • Big Ed_4
    Big Ed_4 Member Posts: 2,806
    Thinking past your fixed solution ....Is it piped reverse return ?

    There was an error rendering this rich post.