Navien NPE-240A and NaviCirc paramaters questions...

Discussion in 'Tankless Water Heater Forum' started by CG ANderson, Jun 6, 2020.

  1. CG ANderson

    CG ANderson New Member

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    Location:
    Eddy Bay, KY, USA
    A laurel, and hearty hello! This is my first post here on this forum. I hope it isn't premature, as I am still learning. I have done quite a bit of searching here, and have found answers to many of my questions. But I wanted to get some more feedback to further my knowledge.

    I just had a Navien NPE-240A tankless system professionally installed. I also had a NaviCirc unit installed under the sink farthest from the unit. Plus NaviLink. We live in a log home and have historically had issues with getting hot water to the upstairs shower. That is, we'd have to run the water for a minute or two before you could even entertain the thought of jumping in. I didn't expect the 240A to solve that issue, so I added the NaviCirc. Because we live in the cabin, and it was essentially built around the plumbing, there is no way to add a dedicated return line for a recirculation system.

    I am not sure the installers were very familiar with the NaviCirc. They did set the #2 jumper to ON. But none of the other parameters indicated in the NaviCirc manual were set. Specifically, I went in and set the P.17 – Enable Thermal Bypass Valve to ON. It had been off. I did not mess with P.12 pump cycle interval time or P.14 return line sampling time. I also set the 2-way valve inside the water heater to “EXT.” It had been set to "INT". It is also of note the recirculation mode on the LED display had been "on" all the time until (after reading a post here) I learned how to set it to come on and go off at certain times in the NaviLink app. Now it is only on when we shower.

    I post all of this to say that, so far, I cannot tell a bit of difference in the time it takes to get hot water to the upper shower. Probably my imagination, but it almost seems like it takes longer! It takes over a minute for the shower to even start to get lukewarm. About three minutes before it is at full temperature. The shower brand is unknown but was installed in 2004. Simple one-handle adjustment for hot/cold. I have the water temperature set to 130F. The installers said something esoteric like "the system will learn your patterns and over time you sill see a difference...". I am not sure this is logical considering I have the recirculation set to specific times anyway.

    Is there anything else I need to configure in my unit I am missing? Maybe I am expecting too much or do not fully understand what to expect out of the NaviCirc. Curiously (again, newbie thought here) I'd expect the hot water line to be at least warm to the touch going into the NaviCirc, but it's ice-cold before I turn on the hot water faucet above it. Shouldn't it be warm if it is recirculating hot water? Even when the unit was set to recirculate 24/7 (before I set schedules in NaviLink) it would always be cold to the touch. Perhaps that isn't very scientific though.

    I certainly appreciate any tips!

    Thanks! Chris

    IMG_20200604_144912-01.jpg IMG_20200606_132558.jpg IMG_20200606_132404.jpg IMG_20200606_132322.jpg
     
    Last edited: Jun 6, 2020
  2. Bannerman

    Bannerman Well-Known Member

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    Location:
    Ontario, Canada
    Your photos do not show a recirculation return line connected to the recirculation return port on the bottom of the unit. This means that the installer expected the return flow will enter the Navien through the cold water inlet as opposed to the recirculation return connection.

    Page 23 of the NPE-240A Installation manual shows the design flow path when configured for an external recirculation loop. As the internal 2-way valve will be closed, the suction side of the pump is to recirculate the water entering the pump from the recirculation return line, but without a return line connected, the pump will not be receiving any water to recirculate.

    Because you are relying on the recirculation flow to return through the cold supply line to the unit, then the cold water feed will need to be connected using a 'Tee' to both the cold water inlet for fresh cold water to enter when hot water is being consumed, AND to the recirculation return port for the recirculation flow to return to the pump inlet.

    The diagram below shows the recirculation path when there is no dedicated return loop. Notice the additional connection to the recirculation return port.

    https://www.navieninc.com/pictures/W1siZiIsIjIwMTkvMDUvMjgvMjEvMDkvMDcvYjFhOWUyZDAtODQ4ZC00ZWM0LWEwNjktMDliZjhlM2FlZTM1L0hvdyBpdCB3b3JrcyBkaWFncmFtLnBuZyJdXQ/How it works diagram.png?sha=2531b2aed305f5a4

    Although not shown in the diagram, a check valve will need to be installed into the cold feed to the unit above the recirc feed 'Tee' to prevent the recirculation pump from creating a small closed loop by pushing flow backwards through the freshwater inlet to the recirculation return.
     
    Last edited: Jun 7, 2020
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  4. CG ANderson

    CG ANderson New Member

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    Bannerman, thank you for this clarification. I am familiar with the diagram below. I guess I assumed this had been done by my installers since they were well aware of my house situation. We expressly spoke of how near-impossible it would be to install a dedicated return line.

    So I need this "T" added off the cold supply line to the recirculation port? Plus the check valve on the same new feed, yes?

    This is a rhetorical question, but shouldn't they have known how to do this properly?

    Chris

     
  5. Bannerman

    Bannerman Well-Known Member

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    Mar 19, 2014
    Location:
    Ontario, Canada
    No. The check valve is to be installed on the existing cold water supply feed.

    I just located a photo from FB that shows as I describe. The check valve is shown on the supply line directly above the Tee. The round ball device is an Amtrol Water Hammer arrestor, likely installed as a precaution. See Joe Wood's photo about half way down page.

    https://www.facebook.com/Navien.Inc...es-the-existing-hot-and-col/2258158097594952/

    You answered that question yourself: "I am not sure the installers were very familiar with the NaviCirc"

    Perhaps this is something you may wish to discuss with them since as an authorized and trained Navien installer, they should have known and you should not have required a follow-up service call to correct a deficient installation.

    Suggest returning the pump setting to Internal temporarily until your installer returns to correct the installation. By resuming an internal loop, the pump will be provided with water to circulate and, the buffer tank temperature will be maintained. With the current configuration , there will be no flow through the buffer tank when there is no hot water use, which is allowing the buffer tank to cool between uses. This is then resulting in hot water flow to faucets to take longer as the water contained in the buffer tank will first need to rise.
     
    Last edited: Jun 7, 2020
  6. CG ANderson

    CG ANderson New Member

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    Bannerman, thank you. I will study the FB photo. I think I understand. For reference, here is what I got. Before reading your additional posts, I assumed that where my fingers are in the second image is what I am missing?

    Chris

    IMG_20200607_094027.jpg IMG_20200607_094039.jpg
     
  7. Bannerman

    Bannerman Well-Known Member

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    Yes. Directly above where your small finger is located is embossed 'RECIRC'.

    The fitting on the supply line where your thumb is located should not be used since that is a cleaning port for descaling the heat exchanger. The additional line will need to be added below.
     
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  8. CG ANderson

    CG ANderson New Member

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    Excellent. I will be on the phone first thing Monday. I did set the internal valve back to INT. Should I also change the P.17 setting back to off? I suppose it wouldn't hurt. You have been a great teacher and helper! Chris
     
  9. CG ANderson

    CG ANderson New Member

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    Just wanted to follow up and end this thread. I had my service company come back and complete the install properly. He admitted this was the first NaviCirc they had installed. So there's that I suppose. But it definitely gets hot water to the farthest sink almost instantaneously now. The adjacent shower went from three minutes down to just over a minute before it is comfortable, which is a vast improvement. I wonder how it is even plumbed reference the sink. Or if that even matters. Still experimenting, and may tweak some of the internal settings on the 240A as per another thread I read on this forum.

    Thanks again! CG

    IMG_20200609_161815.jpg
     
  10. Bannerman

    Bannerman Well-Known Member

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    Congrats that everything is now working properly.

    Some of those settings may be intended for a recirculation system with a dedicated return line. As the NaviCirc limits recirc flow to 1 gpm and also includes a thermostatic valve that will shut-off flow when the water temp reaches 95 degrees F, the function of the NaviCirc may replace some of the internal setting functions.
     
  11. CG ANderson

    CG ANderson New Member

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    Yes, I didn't mess with anything that pertained to the dedicated return line. While I have you on the line...

    We now have a strange vibration in several of the lines. Began after they added the new plumbing. Did not happen prior. You can see and hear it in the upstairs shower head, and it does it also on our other shower. It seems to only last a few seconds when the shower is first turned on. I ran down to the Navien and I could also feel it in the hot water line leaving the unit. Could it be a lack of an expansion tank? The original tank heater had one, but they did not install one on the tankless.

    Here is a link to a video https://photos.app.goo.gl/3eq1xv8abP3EpcqHA

    Chris
     
  12. Bannerman

    Bannerman Well-Known Member

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    That shower head has an internal water powered motor that will cause the water to pulse when spraying from the centre nozzles and/or the 3 mist nozzles as is shown in your video. Alter the flow control position to change the spray pattern to the outer nozzles to determine if the water flow will become constant.

    The pulsation motor can clearly be heard by placing an ear against the shower head while the flow is directed through the centre nozzles.
     
  13. CG ANderson

    CG ANderson New Member

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    I will do this, though we did notice it is temperature-sensitive. If you back off on the hot it stops. Curious why it suddenly started after the NaviCirc was fully functional. Coincidence?
     
  14. Bannerman

    Bannerman Well-Known Member

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    Verify the check-valve is orientated correctly. The flow direction is to be upward, flowing into the cold water inlet port.

    If the check-valve's flow direction is incorrect, then cold incoming water will enter the Navien through the recirculation return port and through the recirculation pump instead of flowing into the heat exchanger with minimal restriction.
     
  15. Bannerman

    Bannerman Well-Known Member

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    Does it also stop when running 100% hot?

    I suspect it maybe a matter of flow rate. PEX has a smaller internal diameter compared to copper and so PEX will have a lower flow rate compared to copper.

    Perhaps the flow rate through 1 PEX line is too low to operate the shower head's pulse motor whereas there maybe sufficient flow when hot and cold lines are both feeding the shower head.
     
  16. CG ANderson

    CG ANderson New Member

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    Check valve, check.

    It only happens when water is running all the way to the hot.

    This has tremendously calmed down. However, I can invoke the pipe shake when the shower is on full and I flush the toilet, robbing the system of cold water. More of a curiosity now more than anything...
     
  17. Bannerman

    Bannerman Well-Known Member

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    Does the pipe shake only occur when the shower head's motorized nozzles (center or mist) are in use, or does it continue when using the outer regular spray nozzles which are not motorized?

    When the shake is occurring, does it correspond to a vibration or noise within the 240-A?

    In reading through the NaviCirc installation manual, there are program settings that are applicable to NaviCirc. Were those settings implimented in the 240-A?
     
  18. CG ANderson

    CG ANderson New Member

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    I will have to experiment with the shower settings. The problem did not manifest itself at all during showers this morning. I couldn't even get it to do it by flushing the toilet while the shower was running. It appears to have become somewhat random in occurrence.

    The first few times it happened, I did feel a vibration on the DHW line leaving the unit. I think I could also feel it in the NaviCirc itself.

    I set all the 240A settings as directed in the NaviCirc manual. I may go back in today and verify they are set correctly.
     
  19. CG ANderson

    CG ANderson New Member

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    One more comment and a follow-up question. The pipe/shower vibration issues has completely gone away. Or, perhaps more precisely, I cannot get it to do it no matter what I do. So that is a good thing. Now, follow up...

    After having the Navicirc installed under the sink adjacent to the shower, I have come to the conclusion that it really hasn't helped get hot water to the shower any more quickly. It definitely does at the sink. And I routinely hear it "come on", so I know it is working. The tepid water coming from the cold is mildly annoying. I suspect the reason it isn't helping the shower much may be the way the shower is plumbed. I would not be surprised that it gets its water supply from a common source in the cellar. I know the plumbing of this log home is a bit odd. Everything is in the walls so I could see how the sink may not be directly "tied" to the shower. Is that a possibility? And, if so, would installing the Navicirc at the shower feed be more appropriate? We are going to have the showers remodeled and that would be the only opportunity to do so. CG
     
  20. Bannerman

    Bannerman Well-Known Member

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    Good to hear about the vibration, but always concerning when no cause has been identified. While the problem is gone for now, will the vibration recur again in the future?

    Many homes are now plumbed with central hot and cold manifolds that feed each fixture individually using PEX piping. Unfortunately, plumbing a home this way leads to the situation you identified, that is, locating a recirculation return valve at the most distant fixture from the WH, may not necessarily assist hot water to arrive quickly to other fixtures even within the same room. If your home is equipped with central manifolds, the hot manifold should remain warm along with the individual hot feed to the sink where the NaviCirc unit is located, but all other feed lines exiting that manifold will remain at room temperature when no hot water has been drawn through them for some time.

    Perhaps the current hot plumbing line that feeds the shower, maybe cutoff and re-plumbed to T directly into the same hot line supplying the sink where the NaviCirc is located. It would be best to T in directly below the sink and before the NaviCirc valve.

    Alternately, perhaps a second NaviCirc valve may be installed within the feed line serving the shower? This way, hot water will be quickly available at both the sink and shower. The NaviCirc for the shower will perform best when located as close as possible to the shower itself.

    Another possible option dependant on findng a suitable path for a continuous length of PEX piping, is to install a dedicated return line from the shower and sink back to the WH. The NaviCirc valve would then not be needed as each hot line at each fixture would flow through a check-valve to ensure the correct flow direction, and also through a partially closed valve that will balance the return flow between the two fixtures. A dedicated return line will also eliminate the tepid cold water situation since the cold water lines would no longer be providing the recirculation return path back to the WH.
     
    Last edited: Jun 28, 2020
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