Is my Navien set up correctly/ & circulating too often?

Discussion in 'Tankless Water Heater Forum' started by Barry Weaver, Sep 10, 2021.

  1. Barry Weaver

    Barry Weaver New Member

    Joined:
    Sep 10, 2021
    Location:
    Cleveland Tn
    We have just built a new home about six months ago. We had a Navien on demand water heater installed. I am concerned if the unit was installed correctly. I have found loose gas fittings and a few leaks since the install. It just makes me second-guess the installers ability. I have a picture of the dip switches. It also seems like it circulates very often. Is it common with these? It does have an internal circulation. It’s on propane and I checked to make sure the propane conversion was done& it is. Thanks

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  2. breplum

    breplum Member

    Joined:
    Oct 2, 2004
    Occupation:
    Plumbing and heating contractor
    Location:
    San Francisco Bay Area
    The icon for faucet spray shows that "recirculation" is set.
    Dip switch 2 is on, so that confirms it.
    I must note that the condensate drain line appears to be 1/2", which is contrary to recommended sizing in PEX because the i.d. is smaller that PVC , and check the fittings, they must not be metal fittings because the condensate is acidic. Plastic fittings are ok.

    With recirc on, it will exercise every 1/2 hour (at least that is what I think the interval is) to check the hot line temperature. One terrific option is to install the Navien Hot Button (On Demand Control) module and then daisy chain push button call for recirc in any room where you want. It is low voltage and makes a lot more sense than always keeping pipes hot.
    BTW, all hot piping throughout the house should be insulated with 3/4" wall insulation.

    Not good: Having tight elbows on the hot water supply line does not contribute to good flow. We normally want to minimize tight elbows because constant recirculation caused erosion.

    FYI, the recirculation "Pump Exercise Operation Interval" is in the set-up Parameters P.13, it sets the circulator idle sit time before activating the pump exercise feature.
     
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  4. Barry Weaver

    Barry Weaver New Member

    Joined:
    Sep 10, 2021
    Location:
    Cleveland Tn
    Thanks breplum so, may I ask this. I looked and the pipe is not insulated but it is in a spray foam wall encapsulated crawl space. Would it make sense to try and insulate it now? Also in my Navien operations manual calls p.13 “pump fix protect period time” or is it p.04 “pump exercise operation time”. Will one of those functions slow this very often circulation down? It’s weird, it’s 90 degrees outside and I hear this unit running a lot. I just don’t want to throw $ away.
    Would the hot button eliminate most of the issues of non insulated and running a lot? Thanks for your information Sir!
     
  5. breplum

    breplum Member

    Joined:
    Oct 2, 2004
    Occupation:
    Plumbing and heating contractor
    Location:
    San Francisco Bay Area
    Last two questions, answer is 'Yes'. Recirc would not run, unless you pushed the hot button (s), you can add quite a few button locations. And you could opt to not invest in insulation if you only ran with a hot button. Better to insulate, though.

    p.04 “pump exercise operation time” is just as described, not very relevant and factory setting is usually fine.
    The built in aquastat will always shut off the recirc pump when it is back up to temp (what we call: aquastat is 'satisfied')
    If the crawl space is accessible, the hot water pipes are supposed to be and should be insulated. It is incomprehensible to any educated person as to why it was not.
     
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