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Tankless common venting

Steve_210 Member Posts: 594
I just seen an install of 4 tankless on the main wall. Looks like a real nice job, but I noticed that all 4 are being common vented with the fresh air being taken from the room. I just checked with Noritz and they say they do not allow common venting. I have a few jobs that if we could common vent, the tankless units would work, but we cannot go individual. Do you know what manufacturers if any allow common venting on their tankless units.



  • Ironman
    Ironman Member Posts: 6,591
    edited February 2011
    Not Noritz


    Those are Eternals.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Steve_210
    Steve_210 Member Posts: 594
    Ok that's one

    Are there any others that can be common vented.
  • Tim McElwain
    Tim McElwain Member Posts: 4,481
    Heres what

    the factory states about Eternal:

    Good Morning Mr. McElwain,


    Thank you for your interest in the Eternal Advanced Hybrid water heaters.


    The GU195M unit, which is designed for use in multiple unit applications, can be common vented for exhaust. Up to four units can share the same exhaust pipe. If you were to do this, you would need to utilize 6" PVC piping for the common run (rising to the run from each unit would require 3" PVC). If you are drawing the combustion area from the space around the units, you would be able to have a maximum run length of 60 feet with a total of 5 90 degree elbows (deducting 5 ft from the run for each elbow).


    I have included with this email a copy of the Eternal's Installation and Operations manual, which includes all of our installation specifications for the Eternal, including for multiple unit installs. If you have any further questions, please feel free to contact Grand Hall.


    Andrew Hall

    Inside Sales

    Grand Hall USA, Inc.

    T. 866.946.1096

    F. 972.279.8440


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