Navien Npe240a- Navilink,Navilink App, Recirculation settings And Parameters

Discussion in 'Tankless Water Heater Forum' started by dradam, Jan 15, 2020.

  1. dradam

    dradam Member

    Joined:
    Sep 21, 2008
    Location:
    Washington, DC
    Navien NPE 240A— Navilink recirculation—some customer insights.



    I have had The Navien NPE240A for about two years now and the unit has worked flawlessly, but it has taken me a while to get my recirculation settings working and recirculation parameters dialed in.

    I thought I would share here some of the things I have learned in the hopes it may help others as they consider this system. I welcome any comments or corrections.

    I was interested in this system because it seemed to offer the most control through their Navilink app, and the ability to control scheduled recirculation.

    I have an older home so a dedicate recirculation line was not an option for me. I am currently set up to recirculate warm water through to my farthest fixture using the cold-water line as a return. I recently upgraded from A Grundfos bypass valve to Naviens’ “Navicirc” bypass valve which I believe has a better flow and a higher closing temp.


    Some things to know before your buy:

    I chose the NPE240A because of its internal tank to provides a small reservoir of instantly hot water. During a recirculation cycle I don’t think this makes much of a difference because the water lines in my home are effectively the water tank. Off recirculation, on demand, this may help.

    In new construction I believe that a dedicated recirculation line to the farthest fixture is the way to go. Using the cold-water lines as the return limits how high the initial temperature can be at the farthest fixture. The Navicirc bypass closes at 95 degrees. This is an effort to not make the cold-water lines too hot. With a dedicated recirculation line, I believe the temperature can be as you set it. I do not at all mind having warmer water in the cold lines during recirculation. While I guess some of that warm water could be going down the toilet, in my household the recirculation times are mainly shower times.

    Navien makes it clear that they will only provide warranty support to units installed by their licensed contractors. While I have tackled many DIY projects this combination of plumbing, gas and venting was clearly best left to a qualified installer. Be careful that your installer has experience with these units. I live outside D.C. and used “Tankless Concepts”. Tankless heaters are all they do. They did a great job for me.

    Navien does not make clear the difference between scheduled recirculation and their “Hot Button”. The hot button ( in the navilink app)does a short recirculation cycle when you hit it bringing hot water to the farthest fixture.(there is also an option for a hard wired hot button) The Navilink app is software based for both IOS and Android. It communicates with their “Navilink” device. The app and the Navilink communicate either CAT5 wired or wirelessly to your router through you homes WIFI setup. The Navilink then controls your NPE. You can set a schedule on the app to tell your unit when to recirculate water through your lines. The scheduler controls the recirculation only. There is a separate switch which can shut down the unit if needed.

    The hot button is different. Even though it uses the same app. The hot button requires installation of a circuit board into the unit. When the hot button is activated scheduling is disabled. You can not have both. This does not make a lot of sense to me. Ideally, I would like to have a schedule in the morning and then be able to use a hot button later in the day if needed off schedule. I see no reason that the app could not incorporate a software based hot button and I have suggested this to Navien.

    There is however a work around… If you disable the scheduler in the app a recirculation cycle will begin. But you must remember to turn it back on again or your device will continue to recirculate.


    My biggest problem over most of my first two years of use was getting the scheduler to work and it came down to a simple issue. There is a button on the app for the weekly scheduler that says “enable” I would set the schedule and hit the enable button. What I recently learned is that the schedule is on when the button says “enable” and off when it says “disable”. Is should read “enabled/disabled” This is a Korean app developer language issue. I have notified Navien of this as well and I see that it has confused many others as well.

    My second biggest issue has been optimizing recirculation parameters. For recirculation Navien is not clear as to the use of parameters. There is always an interval between when water is called for and the start of the burner. During this delay gases are blown out of the exhaust and cold-water flows through the burner unheated leading later to a cold-water sandwich. I hoped that tweaking the parameters might mitigate this effect.

    Follow me here….and I think this is only relevant for those who use the cold system to recirculate. I can’t stop a cold-water flow at initial start up of the burners, but I hoped that by tweaking the parameters I might regulate the temperature of my pipes and soften the blow. Effectively using the water and heat in the piping as a buffer against the initial cold-water startup infusion.

    Three parameters are relevant here:

    P12: Pump Cycle Interval time- The amount of time the pump will run when a recirculation is called for. This was originally set to five minutes by my installer because that is how long it took warm water to get to my farthest fixture. At this setting I was getting a cold-water sandwich. I increased this to six minutes and saw a marked improvement.

    Why? My theory: five minutes got water to the farthest fixture but did not fill up all the returning cold line to the NPE. My shower has a temperature regulator. It draws on both the hot and cold lines to maintain its set temp. If there is already warm water in the cold system, it will pull hot less quickly from the hot system. My thinking is that the cold-water rush at startup will have more time to warm up in the pipes before it hits me. I have only now experienced “warm water sandwiches” but not cold.

    P14: Return line sampling.: I reduced this from default of 30 minutes to 15. My thinking that with more frequent sampling it would pull more warm water into the pipes and keep my ‘Pipe Buffer” hotter. I was concerned that with longer sampling intervals the water in the pipes would cool down more.

    P 15: Recirculation differential temperature: I interpret this as the difference between set temp and the return water temp that will turn initiate a recirculation cycle. The default is 9 F. I have set mine to 5F. I am not sure this can make any difference in a cold-water recirculation line set up because the Navicirc valve closes at 95 degrees F. it may be a more relevant adjustment for those with a dedicated hot water line.

    P16: This is only relevant if you are using the hot button and allows on to determine the recirculation

    time needed to your farthest fixture.

    For the Navilink and recirculation to work:

    P01 must be set to your type of device

    P17 must be on for thermal bypass

    P18 must be on to allow communication with the Navilink.

    I have not adjusted any other parameters as they do not affect recirculation to my knowledge.

    In the unit dip switches and valves must also be set correctly if you are using external recirculation. This is listed in their most recent technical bulletins and should be set up by your installer.

    Final thoughts:

    It has been my impression That the Navicirc works better than the Grundfos valve.

    Endless hot water has been fantastic.

    I added piping to an outdoor hose bib that I can be switched to hot water. I use it to refill my hot tub after cleaning and to fill up my pool at the beginning of a season. Extravagant yes, but the water would be heated regardless and this way it is almost instantaneous.

    I can’t say enough good things about the “Tankless Concepts” the company who did my install. Technical bulletins, the app and other things have changed even since my install and they have been amazingly responsive to my questions.


    Navien has done some recent app updates;

    I believe they have fixed the inability to register with IOS 13, but if not, you can register with a device using an older IOS if you have one.

    There has been an issue with schedules not changing automatically over daylight saving time. This may have been fixed but I won’t know until clocks change again.

    I have asked them to create an app based hot button that does not preclude a schedule as well.

    I have asked them to correctly label the enable/ disable buttons.

    If my thinking is flawed here or if anyone has any helpful suggestions please let me know. I hope this has been helpful.
     
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