Navien NPE-180A Installation Manual page 20

A System with the Internal Circulation Pump
Set the 2-way valve inside the water heater to 'EXT'. For more information about
settings, refer to "Selecting a Recirculation Mode ("A" model only)" in the Water
Heater Installation Manual.
WARNING
An anti-scalding device must be installed in the system in order to limit the
DHW output temperature and prevent scalding. Setting the valve to 115-120℉
is recommended.
Note
 Install a spring check valve for vertical pipe runs. Do not use a swing check valve
with vertical piping.
 Install either a spring check valve or a swing check valve for a horizontal run.
 An outdoor sensor and a flow switch are supplied with the product.
 Use 18 AWG wires for thermostat installation.
 Install certified mixing valves and expansion tanks ONLY.
20 Configuring the Device