Navien NPE 240A with Navicirc Valves

Discussion in 'Tankless Water Heater Forum' started by Pete Carlone, Jun 15, 2020.

  1. Pete Carlone

    Pete Carlone New Member

    Joined:
    Jun 15, 2020
    Location:
    Leesburg, VA
    Greetings. New to this forum but I saw other Navien posts on here so thought I could get some help.

    Here's the story:

    Just moved into a house and the previous homeowners had a Navien NPE 240A installed. I wanted to get it checked out (so that someone could explain to me how it worked overall) and also descaled since I wasn't sure how recently the previous owners had done that. When doing the initial inspection, we observed that it was running in recirc mode but without any recirc valves downstream at any faucet locations and without an external recirc pump (although I know the 240A model has internal and external recirc mode so an external pump is not required if it has recirc valves installed). I had them come and install recric valves (Navicirc brand) at multiple sink locations. So, we have 3 recirc valves at 3 downsteam sinks. In addition to installing the recirc valves at the downstream sinks, they installed a T connection and manual isolation valve from the domestic water supply (cold side) to the recirculation port (previously capped) on the 240A. The 2-way valve was set to INT (for internal recirculation mode) and the dipswitches were set to 1-On, 2-Off, 3-Off. No other settings in the R&D information menu were adjusted.

    My question is about what the right settings are in the 240A for the 2-way valve and the dip switches knowing that I want recirculation and that I now have recirc valves installed (with no external pump). I'm confused by what they did on a couple of levels but they insisted that this is how they always set up the 240As and recirc valves.

    My confusion stems from a couple of things:

    1. I don't understand why there needs to be a connection to the external recirculaton port if it is running in internal reciruculation mode. I feel like that line should have remain capped. Why did they need to connect to this port if they kept the 2-way valve on the internal setting?

    2. If you look at the Navicirc installation manual it shows a T-line connecting to the recirculation port (which is consistent with what they did), but, it also says to set the 2-way valve to external, and to change the dip switches to 1-Off, 2-On, 3-Off. It also says to change a couple of settings in the R&D menu. Is there a reason why they didn't do these things too?

    It seems to me that they should have installed the recirc valves and either left everything in internal recirculation mode (2-way and dip switches) with no connection to the recirc port OR made the connection to the recirc port like they did but also changed the 2-way and dip switches to external mode. Am I off base in thinking it should be one or the other? How would you normally set it up? Will it work as currently configured?

    This was all done in the last 12-hours so I haven't had a chance to test the system performance overall, but, I have a feeling in the pit of my stomach that things are set up quite right. I'm a nuclear engineer by trade so I understand valves, fluid flow etc. I don't however have any specific knowledge of tankless water heaters and I typically leave that to the experts.

    What should I do?
     
  2. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    The 2-way valve is located at the inlet to the internal recirculation pump.

    With the valve set to 'Internal', the pump will be drawing from the Navien's heat exchanger, through the buffer tank, and returning that water directly back to the heat exchanger. This will maintain the temperature of the water within the buffer tank, but will not circulate water through the NaviCirc valves you just had installed.

    With the 2-way valve set to External, the internal pump will be drawing water from the recirculation return connection, which will be the flow returning from the NaviCirc valves. A flow diagram is shown on page 26 of the 240A Installation Manual.

    The additional line between the Navien's Cold inlet and Recirculation Return port is because your home is not equipped with a dedicated recirculation return line, so the cold lines are utilized for recirculation return from each NaviCirc valve. Each NaviCirc valve will stop flow once the hot water arriving reaches 95°F.

    The Navien's Cold Inlet connection allows only fresh water to enter the heat exchanger directly as hot water is being consumed. Since the recirculation pump is to receive water from the recirculation return line, the additional pipe is needed for only the water to return from the NaviCirc valves.

    You mention a 'manual isolation valve' on the incoming Cold inlet feed. I'm not certain what you mean by manual isolation valve but anticipate you are referring to a 'check-valve'. Without a dedicated return line, it becomes necessary to install a check-valve above the new 'T' on the cold feed so as to permit cold water to enter the cold inlet port, but prevent the circulation pump from pushing water in reverse out from the cold inlet, down to the 'T' and through to the recirculation return port. Without the check-valve, there is likely to be a small recirculation loop between the pump outlet to the pump inlet, thereby imparing the return flow from the NaviCirc valves.

    Info for NaviCirc: https://www.navieninc.com/accessories/navicirc

    This thread may also be of interest.
    https://terrylove.com/forums/index....240a-and-navicirc-paramaters-questions.88010/
     
    Last edited: Jun 15, 2020
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  4. Pete Carlone

    Pete Carlone New Member

    Joined:
    Jun 15, 2020
    Location:
    Leesburg, VA
    This is helpful. I think I understand now. With the 2-way valve set to internal recirc mode, all it is doing is recircing within the 240A body and not going out to the Navicirc valves. The 2-way valve needs to be switched to external mode in order to actually recirc to the downstream navicirc valves rather than internal to just the heat exchanger. Is that right? If that is the case, then in my current set up I am still only recircing internally and the NaviCirc valves are not doing anything for me. If that is the case, I need to also switch the dip switches to 1-Off, 2-On, 3-Off correct? Do I need to change anything in the R&D menu?

    They did not install a check valve on the T from the cold supply line to the recirc port. Only a ball valve (see blue handle in the photo). Will this create an issue for me?

    ball valve.jpg
     
  5. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    Correct.

    That is is switch configuration I am seeing on page 26 for external recirc flow to allow pre-heating when using the internal pump.

    Yes.

    As water takes the path of least resistance, there will be much less flow resistance in the few feet from the pump outlet, to the inlet connection, down to the T and back to the pump inlet vs the long path from the pump, through 2 heat exchangers, through the buffer tank, out through the home plumbing to the NaviCirc valves, and then back to the pump inlet through the cold water plumbing.
     
  6. Pete Carlone

    Pete Carlone New Member

    Joined:
    Jun 15, 2020
    Location:
    Leesburg, VA
    As a follow up to the check valve question, the flow diagram in the
    OK. Thanks again for your help. Three more questions:

    1. I made some additions to the flow diagram in the 240A installation manual (pictured below) to show the configuration of the system with the navicirc valves installed. Can you confirm that I have it correct and if so, can you confirm that I have the check valve installed in the right spot (basically where the current copper line is)?

    2. Do I need to make any changes to the R&D menus? See the pics below for pages from the NaviCirc installation manual. It says to enable the thermal bypass valve. Is that thermal bypass valve the NaviCirc valve? What does enabling this do in the 240A computer setup?

    3. While I wait to get the check valve installed should I just leave things as-is (with 2-way in internal recirc mode and dip switches in internal recirc), or should I make the adjustment to those now (even though I'll get some bypass flow without the check valve installed?

    I'm debating whether to call the same company or to get a different one to come out since they don't seem to know how things should be configured. I can do everything myself except for installing the check valve so I will need external help.

    flow diagram.jpg navicirc manual1.jpg navicirc manual2.jpg
     
  7. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    I downloaded the NaviCirc Instalation manual to read through. I find Navien's manuals poorly written as they do not often describe each setting's purpose or the result of a setting change.

    1) Your drawing shows the check-valve in the correct location. The check-valve is actually shown in the NaviCirc installation manual diagram on page 12. Also shown is an optional solenoid valve which again, there is no description of its purpose or why one might be needed or wanted.

    2) The R&D setting changes applicable to NaviCirc are detailed in the NaviCirc manual. I suspect enabling the thermal bypass will cause the circulation pump to run continuously, allowing the flow to be controlled by each NaviCirc valve. I also suspect without the thermal bypass being enabled, an internal thermal sensor will control the pump operation when configured for an internal recirculation loop and when the internal loop reaches a specific temperature.

    3) prob best to remain in Internal recirculation mode until a check-valve is installed. If flowing needlessly in a short loop, no water will be flowing through the buffer tank and so it is likely to cool which may further delay the arrival of hot water to faucets.

    I consider your installer provided an incomplete installation. While I would expect to pay for the cost of the check-valve, the cost of returning and the additional labor to install the CV should not be charged to you - IMO.

    If you wanted to install the CV yourself, I anticipate there are check-valves available with Sharkbite connections so soldering will not be required. A short section of the copper riser would be cut-out with a pipe cutter to make room for the CV. Each pipe section would then slide into the Sharkbite connections after any burrs are removed from the cut pipe ends.
     
    Last edited: Jun 16, 2020
  8. Pete Carlone

    Pete Carlone New Member

    Joined:
    Jun 15, 2020
    Location:
    Leesburg, VA
    My plumber checked with Navien and agrees with what we suggested. They are planning to install the check valve and adjust the settings as listed above.

    One last question: I put in 3 NaviCirc valves total, 1 in each upstairs bathrooms. Is this overkill? I have them already so it's not like I can return them, but, do you see any reason why having all 3 would create an issue? The recirc loop will be longer (and therefore probably running more continuously).
     
  9. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    I recall reading in either the 240A or NaviCirc manual, Navien recommend installing only 1 NaviCirc device per system, located at the fixture that is most distant from the WH.

    When a home is equipped with a main hot line running from the WH in which branch lines are fed from, then with the main line already containing hot water because of recirculation, any delay for hot water to arrive to each faucet will be limited to only the branch line feeding that faucet. This configuration would probably not work well for homes with a central distribution manifold in which each individual fixture is connected using a long PEX line.

    While I do not recall the gpm flow rate specification for the recirculation pump, each NaviCirc will permit 0.53-1.06 gpm flow to the return line (cold plumbing). Even if the pump should flow less than 3 gpm, because each NaviCirc will halt return flow once 95° water arrives, I anticipate the NaviCirc nearest to the WH will close first, which will allow additional flow to the next farthest NaviCirc until it too closes at 95° which will then result in all recirculation flow to the 3rd NaviCirc that is most distant.

    You already have all 3 valves installed so you may wish to proceed to test the system to determine what the results will be. We would be interested to know your findings.
     
    Last edited: Jun 17, 2020
  10. Pete Carlone

    Pete Carlone New Member

    Joined:
    Jun 15, 2020
    Location:
    Leesburg, VA
    Yes, this makes sense. I'll test it out as currently configured with the 3 valves. If things don't seem to be working, I can disconnect the 2 valves closer to the WH and proceed from there with only the furthest valve connected. My hope is that with the 3 valves installed, all 3 upstairs faucets will have warm water nearly instantly and that I didn't waste the money on the 3 valves. But we'll see.
     
  11. Pete Carlone

    Pete Carlone New Member

    Joined:
    Jun 15, 2020
    Location:
    Leesburg, VA
    Well, the saga continues...

    Check valves installed. Went to change the parameters in the R&D and came to find out that the units are 2013 units. So, there is no parameter P17 setup available in the front panel and motherboard for these units (based on phone call with Navien tech support during the plumber visit). So, now I'm back to my original setup before all this even began. Internal recirculation only. They uninstalled the NaviCirc valves and refunded me for the labor and parts costs for them (I can always have them reinstalled later). I do have the option to upgrade the motherboard and front panel to the newest versions (which would allow the parameter changes I want) but I was hesitant to do that because I worry about new circuitry connecting to old devices. I'm plumbed for external recirculation using NaviCirc though. Thought I would throw that question out to you: would you upgrade the electronics to allow for use of the NaviCirc valves in external recirc mode or just live with the additional time/water consumption associated with waiting for hot water a little longer at the far away faucets? Are we sure a newer motherboard and front panel will work with my 2013 units?
     
  12. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    I cannot answer that question re upgrading the electronics. You may wish to discuss possible benefits and pitfalls of the current configuration with Navien vs swapping out the control board. Can they supply a firmware update to your existing board to add that feature? Swapping maybe a straightforward procedure with few risks. IDK

    Without a method to program Enable Thermal Bypass, perhaps there is a hardware method to provide the same result such as unplugging the thermal sensor? Maybe utilizing a timer could enable the pump for a short durations according to schedules that you program?
     
  13. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    Perhaps another option would be to not upgrade your existing control board but instead use a 3rd part recirculation pump and valve. There are a few brands that offer both external pumps and a valve similar to NaviCirc, but I anticipate NaviCirc would also work with an external pump.

    When using an external pump, the 240-A's Internal circulation mode would remain programmed to allow the internal pump to be managed by the internal thermal control to maintain the buffer tank temperature. The external pump would then be controlled by a timer or a smart sensor that automatically identifies usual hot water use patterns and will schedule recirculation only when hot water is usually required.

    http://www.tacocomfort.com/product/smartplus-e-ecm-high-efficiency-instant-hot-water-system/

    http://www.tacocomfort.com/products/systems/instant_hot_water/hotlinkplus/index.html

    https://ca.grundfos.com/products/find-product/comfort-pumps-up-10.html
     
    Last edited: Jun 19, 2020
  14. leocgolfer

    leocgolfer New Member

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    Jul 23, 2020
    Location:
    Ontario, Canada
    .

    I think that solenoid may have something to do if you want to hook up an optional hot button near a sink.

    I have also been told by a Navien distributor the following...
    "You will want to install some type of control for your recirculation as running uncontrolled recirculation (24/7) would result in the warranty on the unit being de-rated from 15 Year Heat Exchanger, 5 Year Parts, 1 Year Labour for controlled recirculation to 5 Year Heat Exchanger, 3 Year Parts, 1 Year Labour."

    This was in response to my questions ...
    "I believe that if I install the Navicirc valve then the re-circulation system would operate 24/7. This means wasting heat energy and possibly hearing water flow noise all night. Is this correct? If I also install the navien remote controller NR-20DU then I would be given access to 3 time of day schedules to control when the re-circulation system will be active. I could recirculate the water in morning, at lunch and in the evening to coincide with the most likely need for instant hot water. Is this correct?
     
  15. Bannerman

    Bannerman Well-Known Member

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    Location:
    Ontario, Canada
    Leo, it seems the Navien distributor did not actually address your questions.

    While the NaviCirc manual indicates a solenoid valve (SV) is optional and not required under most conditions, it doesn't explain conditions where it would be required. As it mentions 'temperature fluctuations may occur during high system flow rates', it sounds to me that some incoming Cold water may enter the recirc return port when there is high water usage so the SV will close to prevent flow through the return port so incoming cold water will be forced to only enter the inlet port. It is not clear if the SV would close for any amount of hot water usage or only when the flow rate exceeds a specific number.

    I anticipate a Hot button will simply activate the recirculation pump, but the SV would need to be open for recirculation to occur so it seems recirc could not occur while hot water is being used to the extent to cause the SV to be closed.

    Perhaps the SV will remain closed any time the recirc pump is not running in which case, depressing the Hot button or a schedule setting could cause the solenoid to open and activate the pump for a specific time frame.
     
    Last edited: Jul 23, 2020
  16. leocgolfer

    leocgolfer New Member

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    Jul 23, 2020
    Location:
    Ontario, Canada
    The SV being used with the hot button was my guess and not the distributor. Your explanation makes sense.... Thanks for that...What are your thoughts on the using a controller to keep the warranty maxed?
     
  17. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    I have not seen where Navien state the warranty would be reduced unless a domestic product is used for a commercial application or a WH used for space heating purposes normally requiring a boiler or combi-boiler, but I may be wrong.

    That said, why recirculate water 24/7 when for most working people, water is typically utilized on a predictable routine basis during the week. Since recirculation's purpose is to reduce the wait time for hot water to arrive and to reduce water wastage clearing cold water from the pipe, recirculation is usually only needed for a few minutes at the start of each routine.

    Because the usage patterns may differ on non-work days, it would seem a schedule would be best utilized for routine workdays, and a Hot button for non-work days. Unfortunately, Navien currently do not allow recirc schedules while a Hot button is also active.

    Perhaps a Hot button located in each washroom, kitchen and laundry room could eliminate the need for schedules and provide the most flexability. The Hot button could be simply activated to commence a 15 or 30 minute recirc timer when entering the room so hot water will have arrived in advance of the person being ready to wash their hands, turn on the shower or start the dish or laundry washer.
     
    Last edited: Jul 23, 2020
    leocgolfer likes this.
  18. leocgolfer

    leocgolfer New Member

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    Well said!
     
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