Navien NPN Installation & Operation Manual page 27

CAUTION
Do not configure the system for DHW
recirculation when it is configured to run an air
handler using the H2Air add-on controller. DHW
recirculation and Navien H2Air configurations
cannot be used at the same time.
3.4.2 External Pump Wire Connection
An external pump may be connected to the water
heater for recirculation applications. When selecting
a circulator, it shall be sized to maintain a flow of
2-4 GPM through the water heater. Follow the
instructions below when connecting the pump wire
accessory to the PCB.
WARNING
Failure to follow the instructions below may
result in property damage, personal injury or
death. To avoid the danger of electric shock,
make sure that the water heater is turned off
before connecting the wire to the PCB.
CAUTION
Do not remove the front cover unless the
●
power to the water heater is turned off or
disconnected. Failure to do so may result in
electric shock.
Configure only the DIP switches that require
●
adjustment according to the instructions
in this manual. Do not adjust any other DIP
switches.
An external pump cannot be used in an
●
external recirculation mode application
utilizing a by-pass Valve.
26 Installing the Water Heater
<Specifications>
Maximum Power Consumption: 150W, 1.5A
●
Length: 6 ft (183 cm)
●
 When using a pump with larger power requirements
than the listed specification above, a relay should be
used to ensure proper operation.
1. Disconnect the power supply to the water
heater.
2. Remove the two upper screws from the
front cover assembly using a Phillips head
screwdriver. Then, release the toggle latch from
the bottom of the front cover assembly to gain
access to the internal components.
3. Remove the 2 screws holding the PCB box in
place and remove the PCB box from the system.
Remove Screws here.