Navien NaviCirc Installation And Operation Manual page 75

For terminal type LWCO appliances, a typical wiring method is
shown below (same voltage for control and burner circuit):
LWCO
Terminals
Jumper
Neutral Live LWCO
To Boiler LWCO Terminals
2.5.3.3 Wiring Diagram - Zone Pump System with
Recirculation
NFC-H boilers can use both the 3 zone heating system and the
DHW recirculation feature. The following wiring diagram shows
the 3 zone system and the DHW external recirculation feature.
75