Navien H2Air Installation Manual page 22

For use with an External Pump, see general guidelines below:
 2 to 4 GPM circulation is recommended.
 150W, 1.5A and lower pumps can be wired to the water heater PCB using the
Navien External Pump Wire (GXXX001319).
 Check the Installation Manual for the specific water heater model for additional
pump wiring guidelines.
WARNING
An anti-scalding device must be installed in the system in order to limit the
DHW output temperature and prevent scalding. Set the temperature to 115-
120 ℉ .
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.
 When using an external pump, connect the pump to the water heater PCB
directly using a Navien External Pump Cable (GXXX001319).
22 Configuring the Device