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Navien 240A2 Post Purge tapping noise

TerryMia Member Posts: 2
Brand new Navien makes a tapping noise in the vent pipe during the Post Purge cycle. The problem is that there is a rental above and the noise is amplified to a loud tapping noise. It is vented with PVC piping in a metal sleeve (that was the original vent). Any suggestions on how to eliminate the tapping noise?


  • GermanPlumber
    GermanPlumber Member Posts: 58
    It sounds like contraction noise when the flue pipe cools down . How is the layout of the flue pipe ? Could there be any other sources for the sound ? 
  • TerryMia
    TerryMia Member Posts: 2
    edited April 2023
    Yes that is what I was thinking - the pipe makes a 45 degree turn to the right, then to the left, then 11 feet up through the wall and out the roof. Is there some sort of insulation I can use?
  • yellowdog
    yellowdog Member Posts: 157
    sounds like youll have to open up the wall to fix it. its probably creaking in a plastic hanger they have buried in the wall. i have a pvc sewer pipe in my basement that makes a ticking sound when the hot dishwasher water drains thru it due to the pipe moving very slightly thru the hanger.
  • dko
    dko Member Posts: 611
    Says the pvc pipe is ran through original metal venting, so the chances are the PVC is actually in contact with some part of the metal. PVC expands and contracts and if it's resting on any of the metal flue I can imagine the tapping noise.