Navien NPE-201A + External re-circulator

Hello,

I moved into a 2008-construction townhome in 2018 and it has a Navien NPE-210A system. Our home also has a Grundfos external water circulator pump with associated bridge connector under the furthest sink away from the water heater. There is no line coming in to the Water Recirculation Inlet of the water heater, and the water heater is in internal recirculation mode only (dipswitch 1 up per https://www.navieninc.com/downloads/npe-a-s-guides-npe-quick-installation-guide-en). As a result, it takes a really long time (and a lot of water) for warm water to reach the sinks on our third floor (where the bedroom sinks are) from the first floor where the water heater is.

My goal is to configure the water heater to allow external recirculation WITHOUT the dedicated recirculation line (which our home does not have). Our PCB appears to be old enough such that it does not have more than param 1 and 2 available (there is mention of a newer board with param 17 for thermal bypass enabling https://terrylove.com/forums/index....on-settings-with-thermal-comfort-valve.71994/ and https://gadgetsgo.com/images-manual/Navien-NaviCirc-30022965A-Installation-Operation-Manual.pdf for the NaviCirc).

The attached photo shows the current connections and location of the external pump. Questions:

1. Is there a configuration with the old PCB that would enable external recirculation through the external pump to deliver hot water throughout the house consistently without the dedicated recirculation line going into the heater?
2. Would the new board enable this by configuring the water heater as if a NaviCirc were installed (dipswitch 1 off, 2 on, param 17 enabled, etc)?

Thank you.

I understand what you are trying to do, but to be honest, I'd recommend consulting Navien themselves for the most accurate answer.

Thanks @havasu . I am attempting to do that in parallel, but their customer support isn't very helpful for end users. They won't disclose any helpful information to a non-plumber.