Navien NHB Series, Installation & Operation Manual

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32 Installing the System Piping
WARNING
Ɣ The boiler, when used in conjunction with an air conditioning
system, must be installed so that the chilled medium is
piped in parallel with the heating boiler. Appropriate valves
must be used to prevent the chilled medium from entering
the boiler.
Ɣ
If the boiler is connected to heating coils located in air
handling units where they can be exposed to refrigerated
air, use flow control valves or other automatic means to
prevent gravity circulation of the boiler water during the
cooling cycle.
3.5.1 Examples of System Applications
Refer to the following examples to properly implement a system
for space heating, DHW supply, or both. These examples are
provided to suggest basic guidelines when you install the boiler
system. However, the actual installation may vary depending on
the circumstances, local building codes, or state regulations. Check
the local building codes and state regulations thoroughly before
installation, and comply with them fully.
Air Handler Interface
The Navien NFB boiler can control the operation of an air handler
when a thermostat is used in combination with the air handling
unit. The Air Handler Interface is designed to stop air handler
operation when the boiler’s space heating function is not
operating due to DHW supply demands, boiler errors, or low water
conditions.
The air handler contacts (A/H) turn off when the following
conditions arise:
Ɣ
The PCB DIP SW2 #7 is set to ON.
Ɣ
Thermostat is turned off.
Ɣ
The boiler is supplying DHW, or it is in stand-by mode for DHW
demand.
Ɣ Level 2 or higher errors occur.
Ɣ The boiler is turned off.
Configuring a Zone System
The NFB boiler can control up to 3 zones utilizing zone pumps.
After installing the system, the boiler operation must be
configured accordingly using the front panel.
Thermostat Configuration for the Air Handler Interface
Set the PCB DIP SW2 #7 to down position (OFF) to use a thermostat
with the Air Handler.
1 2 3 4 5 6
O
N
O
N
1 2 3 4 5 6 7 8
Refer to “3.6.7 Wiring Diagram - Air Handler” on page 42 for
wiring connections.
DHW System
Use the indirect tank when configuring a DHW system that consists
of basic boiler applications or cascade applications.