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Navien tankless gas water heater condensation inside the cabinet

bob eck
bob eck Member Posts: 930
Contractor told me they have a job with an Navien tankless gas water heater that has been in about five years. It has worked fine up until recently where there is excessive condensation inside the cabinet. He told me the Navien TGWH is vented with 2” pvc pipe and fittings with an 2” pvc concentric termination piece going through the wall.
I told him to check the concentric termination piece to see if the inner pipe came apart or if it is cracked and the unit is pulling in flue exhaust instead of fresh clean air. Could this be causing the condensation inside the cabinet?


  • Snowmelt
    Snowmelt Member Posts: 1,416
    Yes that’s it, if you cap that fresh air that will prove your theory. Happened to me on a Utica cub
  • cannibalflea
    cannibalflea Member Posts: 7
    I seems to be happening to my unit. I just posted my situation and photo here. Any thoughts our ideas would be appreciated.
    EBEBRATT-Ed Member Posts: 15,623
    Navien is having issues. Watch some U tube videos and see for yourself