Examples Of Electrical Connections - Navien NHB-055 Installation & Operation Manual

3.6 Examples of Electrical Connections

WARNING
Improperly connecting the electrical supplies can result
in electrical shock and electrocution. Follow all applicable
electrical codes of the local authority having jurisdiction.
Connecting the electrical components should be performed
only by a licensed professional.
CAUTION
Label all wires before disconnecting them when you work on
the controls. Wiring errors can cause imporper and dangerous
operation. Verify proper operation after servicing.
3.6.1 Accessing the Terminal Strips
DANGER
You must ensure that the boiler is disconnected from the
electrical supply before carrying out any servicing inside the
boiler and, particularly, on the electric terminal strips.
To access the PCB, carefully follow the steps below:
1. Turn off the power supply to the boiler.
2. Remove the boiler's front cover by loosening the four screws.
3.6.2 Wiring Diagram - External LWCO
CN10 CN12 CN24
T/T T/T
LWCO
CH DHW
Remove the factory installed jumper on the LWCO
Note
terminals (CN24) prior to connecting the LWCO.
The boiler supplies 24 VAC at the LWCO power
terminals (CN25).
CN25 CN29 CN30
System
System
AC24V
Supply
Return
Output
Temp.
Temp.
(optional)
(optional)
Common
Hot
LWCO
Installing the System Piping 31