Navien NCB-180 Installation & Operation Manual page 22

Contaminant
Total Dissolved Solids (TDS)
Zinc
Navien is not responsible for plugging of the domestic system by
scaling or accumulation of dirt; suitable steps shall be taken by the
installer and user to avoid water quality related issues.
Freeze Protection
Navien recommends heat tracing and insulating the DHW water
pipes. Pipe enclosures may be packed with insulation for added
freeze protection. Freeze damage is not covered by the warranty.
3.2.2 Essential Elements in a DHW System
DHW Heat Exchanger
The DHW heat exchanger installed inside the Navien NCB boiler
has been tested and certified in accordance with IAPMO standard
PS 92-2010.
Drain and Isolation Valves
Install drain and isolation valves on the inlet and outlet of the
DHW heat exchanger, so it can be flushed free of possible build-up
caused by dirt or hard water.
DHW Filter
The Navien NCB boiler has built-in DHW filter at the entrance of
the cold water inlet. Clean the filter periodically to ensure that the
filter is not obstructed creating disturbance in the flow. Failure to
protect the flow sensor from dirt and debris will cause the boiler to
malfunction.
Maximum Allowable Level
500 mg/l
205 mg/l
Flow Restrictor (pressure regulator)
A flow restrictor is used to avoid excessive flow at the faucets. The
Navien NCB boiler has a built-in flow restrictor at the cold water
inlet adapter to limit the overall flow of domestic hot water. Follow
the instructions below when installing a flow restrictor:
CAUTION
Do not operate the boiler without the flow restrictor installed.
Refer to the flow restrictor specifications and install an
appropriate valve for proper operation.
All Navien NCB boilers are shipped from the factory with three flow
restrictors included for different flow rates. Each flow restrictor
allows for a specified amount of water to flow through the unit. A
flow restrictor valve is pre-installed at the cold water inlet adapter
(at the tip of the cold water inlet filter).
The flow restrictors are color coded for easier identification. Refer
to the table below for detailed specification. Factory-installed flow
restrictors and specifications are as follows:
Valve color Applied Model
Orange NCB 240, pre-installed
Yellow NCB 210, pre-installed
Blue NCB 180, pre-installed
* Flow rate in GPM, as factory tested with 56 psi water pressure.
The following graph describes the water flow rate (in GPM) and
water pressure (in psi) specifications for each flow restrictor.
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
14
0 28 42
Specification*
5.6 GPM
5.0 GPM
4.0 GPM
Orange
Yellow
Blue
56 71 85 99 113
Installing the System Piping 21