Navien Intelligent Preheating Setting

Discussion in 'Tankless Water Heater Forum' started by Kal, Feb 14, 2020.

  1. Kal

    Kal New Member

    Joined:
    Jan 8, 2019
    Location:
    Plano, TX
    Just had a Navien 240A installed with a thermal bypass valve for recirculation. The dip switches are set to:
    1 - ON
    2 - ON
    which are the settings for Intelligent Preheating per the manual.

    My question is if Parameter 17 (for thermal bypass valve) should be set to On or Off. It is currently set to OFF and my plumber said that is how they always set things up. Tried calling Navien Tech Support to confirm but they won't answer these types of questions for the homeowner :(. Can anyone here help based on your experience?
     
  2. SoCal Plumber

    SoCal Plumber New Member

    Joined:
    Feb 18, 2020
    Location:
    California

    If you haven’t stumbled across the information, Yes P17 should be on. This allows the Navien to heat water at lower flow rate. With P17 turned off, the flow rate (GPM) is set higher. Meaning the pump could be on and moving water but the flow sensor inside the unit will not start the combustion process because it does not know, sense, that there is a “demand” for hot water.
     
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  4. Kal

    Kal New Member

    Joined:
    Jan 8, 2019
    Location:
    Plano, TX
    Thank you SoCal Plumber! Any recommendation whether to use the intelligent preheating mode vs the regular recirculation mode?
     
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