Navien NFB-175H Guide

WARNING
If the information in these instructions is not followed exactly, a fire or explosion may result,
causing property damage, personal injury, or death.
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this
or any other appliance.
WHAT TO DO IF YOU SMELL GAS
●Do not try to light any appliance.
●Do not touch any electrical switch; do not use any phone in your building.
●Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s
instructions.
●If you cannot reach your gas supplier, call the fire department.
Installation and service must be performed by a qualified installer, service agency or
the gas supplier.
The installation must conform with local codes or, in the absence of local codes, the
National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CSA B149.1, Natural Gas and
Propane Installation Code.
Keep this manual near this boiler for future
reference whenever maintenance or service
is required.
User’s Information Manual
NFB-H Condensing Boilers
Model NFB-175H
NFB-200H

2Contents
Contents
1. Safety Information 3
2. About the Boiler 6
2.1 Description of the Boiler 6
2.2 Parts of the Boiler 6
2.3 The Front Panel 7
3. Operating the Boiler 9
3.1 Turning the Boiler On or Off 9
3.2 Adjusting the System Temperatures 9
3.3 Accessing Basic Menu Items 12
3.4 Resetting the Boiler 13
4. Maintaining the Boiler 14
4.1 Cleaning the Boiler 14
4.2 Draining the Boiler 14
4.3 Cleaning the Air Intake Filter 15
4.4 Protecting the Boiler from Freezing 16
4.5 Maintenance Schedules 17
5. Troubleshooting 22
5.1 Solving Basic Problems 22
5.2 Understanding Error Codes 23

3Safety Information
The following safety symbols are used in this
manual. Read and follow all safety instructions in
this manual precisely to avoid unsafe operating
conditions, fire, explosion, property damage,
personal injury, or death. Keep this manual for
future reference.
DANGER
Indicates an imminently hazardous situation
which, if not avoided, could result in severe
injury or death.
WARNING
Indicates a potentially hazardous situation
which, if not avoided, may result in injury or
death.
CAUTION
Indicates a potentially hazardous situation that,
if not avoided, could result in property damage.
DANGER
If you do not follow these instructions exactly,
a fire or explosion may result causing property
damage, personal injury or loss of life.
A. This appliance does not have a pilot. It is
equipped with an ignition device which
automatically lights the burner. Do not try
to light the burner by hand.
B. BEFORE OPERATING smell all around the
appliance area for gas. Be sure to smell next
to the floor because some gas is heavier
than air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
●Do not try to light any appliance.
●Do not touch any electric switch; do not
use any phone in your building.
●Immediately call your gas supplier from
a neighbor’s phone. Follow the gas
supplier’s instructions.
●If you cannot reach your gas supplier, call
the fire department.
●Do not return to your home until
authorized by your gas supplier or the
fire department.
C. Do not use this appliance if any part has
been under water. Immediately call a
qualified service technician to inspect the
appliance and to replace any part of the
control system and any gas control which
has been under water.
1. Safety Information

4Safety Information
WARNING
●Shut off the gas supply if the boiler is
damaged.
Have your installer or plumber show you
the location of the gas shut off valve and
demonstrate how to close the valve. If the
boiler is damaged as a result of overheating,
fire, flood, or any other reason, close the
manual shut off valve and do not operate the
boiler again until it has been inspected by a
qualified technician.
●Do not store or use gasoline or other
flammable liquids near this boiler.
Doing so may result in fire or explosion.
●Do not place combustibles, such as
newspapers or laundry, near the boiler or
venting system.
Doing so may result in a fire.
●Do not place or use hair sprays, spray
paints, or any other compressed gases near
the boiler or venting system, including the
vent termination.
Doing so may result in fire or explosion.
●Do not operate the boiler with the front
cover opened.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may result
in property damage, personal injury, or death.
●Do not operate this boiler without proper
venting.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may result
in property damage, personal injury, or death.
Inspect the vent termination and air intake
supply annually to ensure proper operation
of the boiler. Turn off and discontinue use
of the boiler if any of the vent pipes, vent
elbows, or intake pipes are damaged in any
way, separated at a joint, or show evidence of
corrosion, rusting, or melting.
WARNING
●Do not touch the power cord or internal
components of the boiler with wet hands.
Doing so may result in electric shock.
●Do not make any electrical connections
before turning off the electrical power
supply at service entrance panel.
Doing so may result in severe personal injury
or death.
California law requires the following Prop 65
warning to be provided:
WARNING
Cancer and Reproductive Harm -
www.P65Warnings.ca.gov

5Safety Information
CAUTION
●Do not attempt to repair or replace any
part of the boiler, unless it is specifically
recommended in this manual.
For all other service, contact an authorized
technician or licensed professional. Improper
adjustments, alterations, service, or
maintenance may lead to property damage,
personal injury, or death and will void your
warranty.
●Do not operate the boiler if you feel
something is wrong with it.
Doing so may result in product damage or
personal injury.
●Do not allow children to operate or access
the boiler.
Doing so may result in product damage or
personal injury.
●Do not turn on the boiler unless the water
and gas supplies are fully opened.
Doing so may damage the boiler.
●Do not use this boiler for anything other
than its intended purpose, as described in
this manual.
●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.
●When servicing the controls, label all wires
prior to disconnecting them.
Failure to do so may result in wiring errors,
which can lead to improper or dangerous
operation.
●Do not use unapproved replacement or
accessory parts.
Doing so may result in improper or dangerous
operation and will void the manufacturer’s
warranty.
●Do not place anything in or around the vent
terminals, such as a clothes line, that could
obstruct the air flow in or out of the boiler.
●This boiler has been approved for use in the
USA and Canada only.
Using the boiler in any other country will void
the manufacturer’s warranty.
●Should overheating occur or the gas supply
fail to shut off, turn off the manual gas
valve to the appliance.

6About the Boiler
2.1 Description of the Boiler
The Navien NFB-H boiler is available in 2 models:
NFB-175H and NFB-200H.
The main features are as follows:
●Power Interruption: When the power is restored
after a power failure, the boiler will automatically
start and return to normal operation. A manual
reset is not required.
●Freeze Protection: A sensor inside the boiler
automatically detects the temperature and,
if necessary, initiates a safety heating cycle to
prevent internal equipment damage due to
freezing temperatures.
●Short-Circuit Protection: Any short-circuit
occurring in the boiler’s electrical circuit
immediately blows the internal glass fuses and
automatically cuts off the gas supply.
●Lightning Protection: Each boiler is specially
grounded, both internally and externally, to
protect against lightning strikes.
●Carbon Monoxide Protection: The boiler is
designed to maintain a safe air-to-gas ratio and
combustion rate. This function is continuously
monitored by the boiler’s combustion controls.
●Auto Fan Detection: The rotation of the fan is
automatically detected and controlled. Fan failure
will stop the operation of the boiler.
●Boiling Prevention: Excessive temperatures will
automatically stop the boiler.
2.2 Parts of the Boiler
2.2.1 Front View
Exhaust
Gas Vent
Combustion
Air Intake
2.2.2 Bottom View
14.6”(370 mm)
2.6”(67mm)
12.1”(308 mm)
6.3”(160.5 mm)
AB C D
17.3”(440 mm)
9.6”(244mm)3.2”(81.7mm)
#Description
AHeating Supply
BHeating Return
CGas Connection
DCondensate Outlet
2. About the Boiler

7About the Boiler
2.3 The Front Panel
The front panel allows you to adjust the
temperature and view the operating status or error
codes. Remove the protective sheet from the front
panel before using it.
2.3.1 Icons and Digital Display
The icons and digital display on the front panel
provide important information required for the
boiler’s operation. Refer to the following table for
detailed information.
aOutdoor reset Displayed when the Outdoor
Reset feature is enabled.
bCombustion Displayed when the burner is
combusting.
c
System check or error
Displayed when an error is
detected or a system check is
needed due to service alarm
overtime.
d
Anti-freeze
Displayed when the boiler
is operating in anti-freeze
mode.
Auto air purge
Displayed when an auto air
purge is being performed.
e
Cascade/Main mode
Flashes when configuring a
cascade system. Turns on solid
if the boiler is set as the Main
unit in a cascade system.
fDHW priority Displayed when the DHW
Priority feature is enabled.
AHU connection
Displayed when the AHU
connection settings are
enabled. If there is a problem
or a connection is being
made, this icon will blink.
gDHW demand Indicates that DHW
demand is present.
hDHW temperature Displays the set and current
DHW temperature.
i
System pressure
Displays the internal water
pressure of the boiler
system.
jOutdoor temperature Displays the outdoor
temperature.
k
Space heating
temperature
Displays the set and
current space heating
temperature.
l
Space heating demand
Indicates the space heating
demands from thermostats
1, 2, and 3.
b
a
d
f
c
l
k
j
g
i
e
h

8About the Boiler
2.3.2 Buttons and Command Dial
Using the buttons and the Command dial ( ) on
the front panel, you can turn on or off the boiler,
monitor the current operation status, and set the
values required for the boiler’s operation, such as
space heating and DHW supply temperatures. Refer
to the following table for detailed information.
aBack button Return to the previous menu
or screen.
bMode button
Enter the boiler’s main menu.
cPower button
Turn on or off the boiler. d
Command dial
Rotate to switch between
menu items, or to increase/
decrease values.
Press to make a selection or
to confirm changes.
c
b
d
a

9Operating the Boiler
WARNING
Follow the instructions below to avoid unsafe operating conditions that could cause property damage, severe
personal injury, or death.
●Ensure that the boiler is filled with water before turning it on.
●If overheating occurs or the gas supply fails to shut off, shut off the gas supply to the boiler by using the
manual gas valve.
●If any part of the boiler has been submerged in water, do not use this appliance and immediately call a
qualified service technician. The boiler must be replaced.
3.1 Turning the Boiler On or Off
To turn the boiler on or off, press the Power button ( ).
When the power is on, the boiler automatically enters normal operation mode, and the boiler’s operating
conditions are displayed on the screen.
Note The boiler status icons remain displayed when the boiler is turned off.
3.2 Adjusting the System Temperatures
In normal operation mode, space heating teperature for each zone can be set depending on the settings in the
following table.
Settings Space heating settings
Zone Priority Settings Zone Settings Pump 1 Settings
Disable N/A N/A Space heating temperature settings
Enable Zone Pump System DHW Pump
Space heating temperature settings
for Zone 2 and Zone 3 (Pump 1
Settings”is set to“DHW Pump”.)
Enable Zone Pump System Zone1 Pump Space heating temperature settings
for Zone 1, Zone 2 and Zone 3
Enable Zone Valve System DHW Pump (Default) Space heating temperature settings
for Zone 1, Zone 2 and Zone 3
3. Operating the Boiler

10 Operating the Boiler
3. Rotate the Command dial ( ) to the right or
left to increase or decrease the temperature.
4. Press the Command dial ( ) to confirm the
new temperature.
5. Press the Back button ( ) to return to normal
operation mode, or rotate the Command dial
() to adjust other operation conditions.
You can adjust the temperature while the
highlighted section is flashing. Once the flashing
stops, the current temperature setting is stored.
3.2.2 Adjusting the Space Heating
Temperature (When “3. Zone Priority
Setting”is enabled)
To adjust the heating temperature:
1. In normal operation mode, rotate the Command
dial ( ). The space heating temperature ( ) is
highlighted on the screen.
3.2.1 Adjusting the Space Heating
Temperature (When “3. Zone Priority
Setting”is disabled)
To adjust the heating temperature:
1. In normal operation mode, rotate the Command
dial ( ). The space heating temperature ( ) is
highlighted on the screen.
2. Press the Command dial ( ) to select the space
heating temperature. The highlighted section
will flash.