Navien NR-180 Installation Manual page 40

Gas Water Heater Installation
2. Case II : NR, NP MODEL Recirculation
Slave n-15
Communication Cable
Hot Cold Gas
"B"
DHW Supply
 Install Check valve in either "A" or "B".

Navien recommends to use "A" Series for recirculation.

Because NR/NP models don't have circulation pumps inside, external pump
shall be installed to use recirculation function, additional pump could be
installed out of the unit. In this case be sure to set the head pressure and
flowrate of the pump properly to enable each unit's flowrate to be more than 2
GPM.
40
Slave n-1 Master
Hot Cold Gas Hot Cold Gas
"B" "B"
Aquastat
Remote Controller
(NR-10DU)
SYMBOL
Union
BALL VALVE
CHECK VALVE
Circulation Pump
Faucet
Expansion Tank
Pressure Relief Valve
Gas Supply
"A"
Cold Water Supply