Navien NPE-240A and NaviCirc Installation Question

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pmd5700

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Hello,

I just had my Navien NPE-240A (EDIT: It's actually an NPE-240A2) and NaviCirc installed today. First time tankless user. I was reviewing the manual and installation after they left, and I don't think they have the NaviCirc hooked up properly, and I want to confirm before I call them back out here.

1) They have the internal valve set to "Internal Recirculation".
2) The mode in the settings is set to "Internal Recirculation".
3) I think, even if the settings were correct, that I would need a check valve in the cold water supply line after the tee.

I have no problem adjusting the settings and internal valve, but I think I would rather have them install the check valve if it's required. I just want to make sure I'm not overlooking something here and that there is a check valve installed (internally or externally).

Thank you.

IMG-1273.JPG IMG-1275.JPG
 
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fitter30

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Look at page 21 install manual there is a two way valve that needs to be turned for internal recirculation they didn't need the piping external.
 

Bannerman

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NaviCirc requires External circulation mode for both the DIP switch settings and the 2-way valve.

Because the bridge pipe is bridging both the supply and recirculation return connections, a check-valve is required above the T on the supply line to prevent the pump from pushing water backwards through the supply line connection to the circulation return connection in a small circulation loop.
 

pmd5700

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Look at page 21 install manual there is a two way valve that needs to be turned for internal recirculation they didn't need the piping external.
In my copy of the manual, Page 21 has the gas hookup.

NaviCirc requires External circulation mode for both the DIP switch settings and the 2-way valve.

Because the bridge pipe is bridging both the supply and recirculation return connections, a check-valve is required above the T on the supply line to prevent the pump from pushing water backwards through the supply line connection to the circulation return connection in a small circulation loop.
The manual shows changing the valve from INT to EXT and changing the setting via the keypad. No mention of the dip switches.
Manual 1.PNG
 

Bannerman

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The appropriate settings for NPE-240A External Recirculation are as the diagram below.

The manual page you posted pertains to NPE-240A2 in which case, the DIP switch adjustements have been replaced with settings adjustments performed on the front digital panel.

npe-recirc-flow-external-3.jpg



The diagram below is from the NaviCirc manual. The check valve is required to correctly utilize Navicirc, regardless of whether the Hot Button option will be installed or not. The solinoid valve shown on the circulation return line is optional.
index.php
 
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dlinsley

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In my copy of the manual, Page 21 has the gas hookup

Do you have an A2 then? My A2 and Navicirc were installed a couple of weeks ago, and the installer configured it as per page 34 (nothing connected to the recirc inlet, which is new for A2 unless the diagram is wrong, but it is working well here and the installer is listed as a Navien Service Specialist on Navien's site) with the Int-Ext valve set to Ext and the menu set to External recirc.

upload_2021-10-26_14-52-44.png
 

Bannerman

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The A2 manual shows the internal circulation pump is situated in a much different location than in the prior A models. The A2 pump location will now allow return flow to be drawn through either the Recirculation Supply connection or the Domestic Water Supply connection. Compare below.

The name of this thread vs the Manual page pmd5700 posted, makes it uncertain if his unit is an original NPE-240A, or an NPE-240A2 model.

NPE-240A Recirculation Flow path:
npe-recirc-flow-external.jpg


Link to page 28 of Navien NPE-240A2 manual:

https://www.manualslib.com/manual/2131563/Navien-Npe-180a2.html?page=28#manual
 

pmd5700

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The A2 manual shows the internal circulation pump is situated in a much different location than in the prior A models. The A2 pump location will now allow return flow to be drawn through either the Recirculation Supply connection or the Domestic Water Supply connection. Compare below.

The name of this thread vs the Manual page pmd5700 posted, makes it uncertain if his unit is an original NPE-240A, or an NPE-240A2 model.

Apologies, I do have the A2. I'm still a little confused though. Do I need to set the valve and mode to External Recirculation or Internal? I have the valve going into the Recirculation Port closed and both valve and setting set to Internal and the NaviCirc does not appear to be working.
 

Bannerman

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You require External circulation.

With the 2-way valve set to internal, the pump will be drawing water through the heat exchanger > buffer tank > check valve and back through the heat exchanger in a small loop.

Placing the 2-way to External, will cause the pump to draw from the home's recirculation loop including the NaviCirc valve.

I understand the digital setting for External mode will cause the pump to operate longer and at a higher flow rate each cycle.
 

pmd5700

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Thanks again! So if I understand it right, for my NPE-240A2, I need to set the internal valve to Ext. and the mode to External Recirculation. Then, as long as it's plumbed up like my sketch below, it should work?

Capture.PNG
 

dlinsley

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Thanks again! So if I understand it right, for my NPE-240A2, I need to set the internal valve to Ext. and the mode to External Recirculation. Then, as long as it's plumbed up like my sketch below, it should work?

That is how mine is configured, with External Pump set to No.
 

pmd5700

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That is how mine is configured, with External Pump set to No.
So valve to Ext. but setting to Internal Recirculation? And it works as intended?

EDIT: I re-read your post and see you said External Pump to No. I assume then that the valve and A2 internal setting are both set to External Recirculation.
 
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dlinsley

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So valve to Ext. but setting to Internal Recirculation? And it works as intended?

EDIT: I re-read your post and see you said External Pump to No. I assume then that the valve and A2 internal setting are both set to External Recirculation.

Sorry, yes that is correct. Value set to External. Recirculation set to External, but No to External pump (so that the internal pump is used). In my case I then have Hot Button set instead of Always / Intelligent / Weekly (Schedule). I'll be documenting my Hot Button automation soon.
 

pmd5700

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Sorry, yes that is correct. Value set to External. Recirculation set to External, but No to External pump (so that the internal pump is used). In my case I then have Hot Button set instead of Always / Intelligent / Weekly (Schedule). I'll be documenting my Hot Button automation soon.

Ok, that makes sense - and I think I proved it's working now - kind of. I realized that they installed a Grundfos Comfort Valve instead of the NaviCirc. I don't think the Grundfos valve allows for enough flow. I can see the unit kick on the flow only goes to around 0.5gpm then it shuts off shortly after. I'm guessing it's shutting off due to the low flow.

I suppose this is a new issue/question now. Does anyone have any info on these Grundfos valves? I can't really find much online about them. I found one review that said they only operate at around 0.2 gpm...
 
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