35
Installing the System Piping
Thermostat Configuration for the Air
Handler Interface
Set the PCB DIP SW2 (Set of 8 Switches) #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 the “3.7.9 Wiring Diagram - Air Handler” on
page 54 for wiring connections.
WARNING
●
Do not turn the power on until electrical
wiring is finished. Disconnect power
before servicing. Death or serious injury
from electrical shock may result if power is
supplied to the boiler during electrical wiring
or servicing.
●
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.
●
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.
Expansion Tank
The expansion tank must be sized in accordance
with the water volume of the system as well as the
firing rate of the appliance. It is important to locate
the expansion tank, and make-up water connection,
on the inlet side of any pump in the system, as
doing so will guarantee the lowest pressure in the
system will be at least equal to the tank and make-
up water pressure.
Ensure the expansion tank cannot become isolated
from the boiler anytime the system is operating.
Failure to follow these instructions may lead to
discharge from the pressure relief valve, which may
result in property damage or injury.
Note
The installation of check valves,
motorized valves or other shutoff
appliances (other than for the purpose of
servicing) are not permitted between the
location of the “Closely Spaced Tees” and
the expansion tank.
Air Handler Interface
The Navien NFC-H 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:
●
The PCB DIP SW2 (Set of 8 Switches) #7 is set to
ON.
●
Thermostat is turned off.
●
The boiler is supplying DHW, or it is in stand-by
mode for DHW demand.
●
Level 2 or higher errors occur.
●
The boiler is turned off.
CAUTION
●
Do not remove the front cover unless
the power to the boiler is turned off or
disconnected.
Failure to do so may result in
electric shock.
●
Configure only the DIP switches that require
adjustment according to the instructions
in this manual. Do not adjust any other DIP
switches.
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