Connecting External Devices (Field Wiring Guidelines) - Navien NHB Series Installation & Operation Manual

3.7 Connecting External devices (Field
Wiring Guidelines)
To connect external devices to the controller terminals of the main
PCB, remove the front cover, and then refer to ""11.5.2 Setting the
Space Heating Operation". " For detailed wiring information, refer to
""3.6 Examples of Electrical Connections". "
3.7.1 Thermostat
Connect thermostats to the T/S ZONE1, 2, and 3 terminals (CNC1,
CNC5, and CNC6). Also, install thermostats in walls where they are
not interfered with by vents, hot or cold water pipe lines, lighting,
televisions, or sunlight.
Note
If the Pump1 Setting menu on the SH Control menu is
set to Zone1 Pump, Thermostat 1 cannot be used.
3.7.2 DHW Thermostat
Connect an indirect water heater (DHW) thermostat to the T/S
DHW terminal (CNC7).
If the DHW Demand menu on the DHW Control
Note
menu is set to Tank Sensor, the DHW thermostat is
ignored.
If the Pump1 Setting menu on the SH Control menu
is set to Zone1 Pump, the DHW thermostat is
ignored.
3.7.3 DHW Tank Sensor
Connect the Navien universal temperature sensor (#GXXX001769)
to the DHW TANK terminal (CNT4).
The boiler tank temperature can be adjusted if a DHW tank
sensor is installed. If the tank temperature decreases below the
set temperature of 5°F (3°C), the boiler starts and stops operating
when the set temperature is reached. The values of the DHW
Demand On/Off Differential can be adjusted by setting the
parameters.
If the DHW Demand menu on the DHW Control
Note
menu is set to Aquastat, the DHW tank sensor is
ignored.
If the Pump1 Setting menu on the SH Control menu
is set to Zone1 Pump, the DHW tank sensor is
ignored.
If the Navien universal temperature sensor
(#GXXX001769) is not compatible with the DHW
tank, use a DHW thermostat to control the boiler.
3.7.4 System Supply/Return Sensor
Connect the system supply/return sensors to the SYSTEM SUPPLY
terminal (CNT1) and the SYSTEM RETURN terminal (CNT2).
If the Navien universal temperature sensor (#GXXX001769)
is installed to the secondary loop, the system supply unit
temperature can be adjusted. It controls the boiler's heat and
maintains the system supply temperature at the set temperature.
To select the space heating control method, tap the
Note
Control button (
then select Sys Supply (System Supply Temperature)
or Sys Return (System Return Temperature) on the SH
Control Method menu.
3.7.5 Outdoor Temperature Sensor
Connect the Navien outdoor temperature sensor to the OUTDOOR
terminal (CNT3). Also, install the sensor on the wall and avoid areas
with temperature fluctuations due to direct sunlight, and where
the temperature may not be representative of the true outdoor
temperature.
3.7.6 Flow Switch
Remove the jumper cable connected to the FLOW SW terminal
(CNC9) and connect a flow switch to the FLOW SW terminal
(CNC9). The flow switch is installed at the bottom of the boiler and
is used to the check water flow through the boiler.
3.7.7 Manual Reset Safety Switch
Connect an external safety device, such as a louver switch or a
low gas pressure switch, to the MANUAL terminal (CNC8). Only
external safety devices with relay output contacts are available.
Even if an error from the connected external safety device occurs,
the error is cleared with a manual reset.
To select the contact type for the connected
Note
external safety device, tap the Set button (
Connection on the screen, and then select N-Open
(Normal open type) or N-Closed (Normal closed type).
) > SH Control on the screen, and
) > Ext
Installing the System Piping 45