Navien NPE External Recirculation Confusion

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Hey Siri

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The Navien NPE-210A2 installer manual (under 'External Recirculation', (p 84) says:

"A2-type models must be set to use an external pump".

Is this right? The A2 models have an internal pump, I'm set up to use external recirculation with a hot button, and it does seem to be working, so what gives? I of course assumed that external recirculation would use the internal pump. Is this just a typically confused Navien explanation?

Bonus question: the manual mentions 'energy saver' but I don't see where that can be set.
 

breplum

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That quote just means that during the set-up sequence, when it displays the numerous questions, that you have to select what you want. It has been three days since I set up one and I don't remember which the default option is.
 

Hey Siri

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Ok, thanks, good to know.

Next question, also due to bad technical writing: what does 'pump exercise' actually do? I have a hot button installed, so recirc only happens when the button is pushed, but something noisy is happening in the middle of the night at ~2 or 3 hour intervals. Possibly the pump getting its exercise?
 

Bannerman

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Because the S2 models are not equipped with an internal pump, they are automatically configured for an external pump when circulation is selected.

Since the A2 models are equipped with an internal circulation pump, they are pre-configured for the internal pump and to utilize an external pump, the configuration settings will need to be changed.

When there is a re-circulation loop, there is a concern the water in the loop may stagnate when no circulation has occured for an extended period such as while the occupants are away on vacation. The Pump Excercise feature is intended to periodically activate the pump to ensure the water will be circulated and to also ensure the pump seals will not dry out.

The default Excercise setting will activate the pump for 30-seconds every 24-hours, but the activation time is adjustable to between 1-240 seconds, and the interval is ajustable to between 1-hr and 48-hours.
 
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RealityCheck

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I recently installed a NPE-180A2. Also was a bit confused with the recirc, and having to set both the physical switch and the software to external for the recirc line.
Ours recently started going off during the night as well. I believe this is an 'anti-freeze' feature, so hopefully it is short-lived.
Here is the response I got from their tech support as to the parameters:

"The unit is recirculates when it pick up a 10 degree drop in the water temperature in the unit and line and will cycle on and off about every 30 minutes when cold out"
 
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