Navien NHB Series, Installation & Operation Manual

Page: 36 / 135

36 Installing the System Piping
3.6.2 Wiring Diagram - External LWCO
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LWCO
LWCO
LINE
LINE
Neutral
Note
The boiler supplies 24 VAC at the LWCO power
terminals (CNC3).
For terminal type LWCO devices, a typical wiring method is shown
below (same voltage for control and burner circuit):
LWCO
Terminals
To Boiler LWCO Terminals
Neutral Line
Jumper
LWCO
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 improper and dangerous
operation. Verify proper operation after servicing.
Note
The installation must comply with National Electrical
Code and any other national, state, provincial or local
codes or regulations. In Canada, CSA C22.1 Canadian
Electrical Code Part 1, and any local codes.
Wiring must be N.E.C. Class 1. If original wiring as
supplied with boiler must be replaced, use only type
105 °C wire or equivalent.
Boiler must be electrically grounded as required by
National Electrical Code ANSI/NFPA 70 – latest edition.
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. Unfasten the 4 latches (2 at the top and 2 at the bottom)
to remove the front cover and gain access to the internal
components.