Navien NPN-160U Guide

WARNING
If the information in these instructions is not followed exactly, a re or explosion may result,
causing property damage, personal injury or death.
Do not store or use gasoline or other ammable 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 re department.
Installation and service must be performed by a qualied 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.
When applicable, the installation must conform with the Manufactured Home Construction and
Safety Standard,Title 24 CFR, Part 3280.
Do not install this water heater in a recreational vehicle, trailer, boat or other vehicular type unit as it
will result in a Carbon Monoxide Poisoning Hazard.
Keep this manual near this water heater for future
reference whenever maintenance or service is required.
* The wetted surface of this product contacted by consumable
water contains less than one quarter of one percent (0.25%)
of lead by weight.
User’s Information Manual
NPN Non-Condensing Water Heaters
Model NPN-160U
NPN-180U
NPN-199U
NPN-120E
NPN-160E
NPN-180E
NPN-199E
* Lead Free

2Contents
Contents
1. Safety Information 3
2. About the Water Heater 7
2.1 Description of the Water Heater 7
2.2 Parts of the Water Heater 7
2.3 The Front Panel (Indoor Models Only) 8
2.4 Remote Controller (Outdoor Models -
Optional for Indoor Models) 9
3. Operating the Water Heater 10
3.1 Turning the Water Heater On or Off 10
3.2 Adjusting the Water Temperature 11
3.3 Viewing Basic Information (Indoor
Models Only) 12
3.4 Resetting the Water Heater 12
3.5 Entering Lock Mode 13
3.6 Setting the clock 13
3.7 Setting the Recirculation timer 14
3.8 Starting Recirculation 15
3.9 Canceling all timer settings 15
4. Maintaining the Water Heater 16
4.1 Cleaning the Water Heater 16
4.2 Draining the Water Heater 16
4.3 Flushing the Heat Exchanger 17
4.4 Cleaning the Inlet Water Filter 19
4.5 Protecting the Water Heater from Freezing 19
5. Troubleshooting 21
5.1 Solving Basic Problems 21
5.2 Understanding Error Codes 22

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, could result in injury or
death.
CAUTION
Indicates a potentially hazardous situation
which, if not avoided, could result in property
damage.
WARNING
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
ƔDo not try to light any appliance.
ƔDo not touch any electrical switches or
use landline phones.
ƔFrom a neighbor’s phone, call your gas
provider and follow their instructions.
ƔIf you cannot reach your gas supplier, call
the fire department.
C. Use only your hand to push in or turn the
gas control knob. Never use tools. If the
knob will not push in or turn by hand,
don’t try to repair it, call a qualified service
technician. Force or attempted repair may
result in a fire or explosion.
D. 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

4 Safety Information
DANGER
HOT
BURN
To prevent burns:
ƔUse the lowest operating temperature setting
necessary to provide comfortably-hot water.
ƔIf your household has children or elderly or
disabled residents, using a lower temperature
setting is recommended.
ƔDo not leave children, the elderly, or disabled
persons unsupervised.
ƔDo not allow small children to play
unsupervised in the bathroom.
ƔDo not allow anyone to change the water
temperature while hot water is running.
ƔRead all the instructions in this manual
carefully before changing the temperature
setting.
ƔFeel the water before using it on children, the
elderly, or the disabled.
ƔIf it is necessary to set the water temperature
above 125 °F (52 °C), consider installing a
thermostatically-controlled mixing valve
or temperature-limiting valve. Contact a
licensed plumber or your local plumbing
authority for more information.
DANGER
This water heater’s water temperature is set
to 120 °F (49 °C) at the factory for your safety
and comfort. Increasing the temperature
increases the risk of accidental scalding. Water
temperatures at or above 125 °F (52 °C) can
cause instant scalding, severe burns, or death.
Before you decide to change the temperature
setting, read the following charts carefully.
Water
Temperature
Time in which a young child
can suffer a full thickness
(3rd degree) burn
160 °F (70 °C) Less than 1 second
140 °F (60 °C) 1 second
130 °F (55 °C) 10 second
120 °F (49 °C) 10 minutes
100 °F (38 °C) very low scald risk
Before setting the temperature at or above
125 °F (52 °C), consider installing a thermostatically-
controlled mixing valve or temperature-limiting
valve. Contact a licensed plumber or your local
plumbing authority for more information.

5Safety Information
WARNING
ƔDo not operate this water heater without
proper venting.
Doingso may resultin fireor 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
water heater. Turn off and discontinue use of
the water heater 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.
ƔDo not touch the power cord or internal
components of the water heater with wet
hands.
Doing so may result in electric shock.
California law requires the following Prop 65
warning to be provided:
WARNING
Cancer and Reproductive Harm -
www.P65Warnings.ca.gov
WARNING
ƔShut off the gas supply if the water heater
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 water heater is damaged as a result of
overheating, fire, flood, or any other reason,
close the manual shut off valve and do not
operate the water heater again until it has
been inspected by a qualified technician.
ƔDo not store or use gasoline or other
flammable liquids near this water heater.
Doing so may result in fire or explosion.
ƔDo not place combustibles, such as
newspapers or laundry, near the water
heater or venting system.
Doing so may result in a fire.
ƔDo not place or use hair sprays, spray
paints, or any other compressed gases
near the water heater or venting system,
including the vent termination.
Doing so may result in fire or explosion.
ƔDo not remove the front cover unless the
power to the water heater is turned off or
disconnected.
Failure to do so may result in electric shock.
ƔDo not operate the water heater 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.

6 Safety Information
CAUTION
ƔThis water heater has been approved for use
in the USA only.
Using the water heater in any other country
will void the manufacturer’s warranty.
ƔShould overheating occur or the gas supply
fail to shut off, turn off the manual gas valve
to the appliance.
ƔDo not use this appliance if any part has
been under water.
Immediately call a qualifed service technician
to inspect the appliance and to replace any
part of the control system and any gas control
which has been under water.
CAUTION
ƔDo not attempt to repair or replace any part
of the water heater, 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.
ƔDo not operate the water heater if you feel
something is wrong with it.
Doing so may result in product damage or
personal injury.
ƔDo not allow children to operate or access
the water heater.
Doing so may result in product damage or
personal injury.
ƔDo not attempt to change the water
temperature while the water heater is being
used.
Doing so may result in personal injury.
ƔDo not turn on the water heater unless the
water and gas supplies are fully opened.
Doing so may damage the water heater.
ƔDo not turn on the water if the cold water
supply shut-off valve is closed.
Doing so may damage the water heater.
ƔDo not use this water heater for anything
other than its intended purpose, as
described in this manual.
ƔWhen 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. Verify proper operation after
servicing.
ƔDo not use unapproved replacement or
accessory parts.
Doing so may result in improper or dangerous
operation and will void the manufacturer’s
warranty.
ƔDo 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 water
heater.

7About the Water Heater
2.1 Description of the Water
Heater
The NPN-series water heater is available in 7 models:
NPN-160U, NPN-180U, NPN-199U, NPN-120E, NPN-
160E, NPN-180E, and NPN-199E.
The main features are as follows:
ƔPotable domestic hot water and combination
space heating
ƔMaximum temperature: 140 °F (60 °C)
ƔStainless steel Heat Exchanger with stainless steel
piping
2.2 Parts of the Water Heater
Air IntakeAir Intake
Exhaust Gas
[NPN-160U/180U/199U]
Air Intake Air Intake
Exhaust Gas
[NPN-120E/160E/180E/199E]
2.2.1 Bottom View
c
a
b
# Description Remark
a Hot Water Outlet Connection
b Cold Water Inlet Connection
c Gas Inlet
2. About the Water Heater

8 About the Water Heater
2.3 The Front Panel
(Indoor Models Only)
The front panel allows you to adjust the water
temperature and view the operating status or error
codes. Remove the protective sheet from the front
panel before using it.
a
Error
g
Master Unit
A code will appear on the display Cascade operation
b
Hot Water Recirculation
h
Display
Recirculation Mode
c
Diagnostics button
i
Up button
For installers only Increases the temperature
d
Information button
j
Down button
Shows basic information Decreases the temperature
e
Reset button
k
Power button
Resets the water heater (When an error
occurs) Turns the water heater on or off
f
Combusting
When the gas burner is on
a
b
c
d
e
f
g
h
i
j
k

9About the Water Heater
2.4 Remote Controller (Outdoor Models - Optional for Indoor Models)
LCD display
Indicates functions and
current status.
LED indicator
Indicates the status of
water heater.
- Green: Normal Mode.
- Red: Error occurred.
OK button
Confirms the selection.
Power button
Turns the remote
controller on or off.
Lock button
Locks the other button
operations.
Down button
Decrease the temperature
or value.
Up button
Increase the temperature
or value.
Preheat & Timer button
- Access the timer settings.
- Recirculation ON.
Timer is set. Recirculation Mode.
Displays the current time. Hot water is in use.
Displays the current set
temperature. Water heater operation is in progress.
Operations are locked. An error code will appear on the
display.

10 Operating the Water Heater
WARNING
Follow the instructions below to avoid unsafe
operating
conditions that could cause property damage,
severe personal
injury, or death.
ƔEnsure that the water heater is filled with
water before turning on the water heater.
ƔIf overheating occurs or the gas supply fails to
shut off, shut off the gas supply to the water
heater at the manual gas valve.
ƔIf any part of the water heater has been
submerged in water, do not use this
appliance and immediately call a qualified
service technician. The water heater must be
replaced.
3.1 Turning the Water Heater On
or Off
To turn the water heater on or off, press the Power
button.
[Indoor Models]
[Outdoor Models with Remote Controller]
When the power is on, the temperature will appear
on the front panel display.
[Indoor Models] [Outdoor Models with
Remote Controller]
3. Operating the Water Heater

11Operating the Water Heater
or
[Outdoor Models with Remote Controller]
Note The water heater will retain your
settings during a power outage.
You can adjust the temperature by the increments
as shown below based on the desired temperature
range.
Temperature range Adjusting the water
temperature
98 °F-140 °F
(Fahrenheit mode)
36 °C-60 °C
(Celsius mode)
1 °F or 0.5 °C
increments
The water heater will not provide hot water instantly
at the hot water faucet unless a recirculation line has
been installed from the furthest fixture back to the
water heater.
3.2 Adjusting the Water
Temperature
WARNING
Before adjusting the water temperature, read
“To prevent burns:” on page 4 carefully.
Water above 120 °F can cause instant scalding,
severe burns, or death.
The water heater is set to 120 °F (49 °C) by default.
To adjust the water temperature:
1. Make sure that all hot water faucets are closed,
and ensure that the internal circulator and any
external circulating pumps are off.
Note If a hot water faucet is open, you
can adjust the temperature only
from 98-110 °F (37-43 °C).
2. Press the + (Up) or – (Down) buttons until the
desired temperature appears on the display. You
can adjust the temperature while the display
is flashing. Once the display stops flashing, the
temperature setting is stored.
[Indoor Models]

12 Operating the Water Heater
3.4 Resetting the Water Heater
If an error message appears, you can try resetting
the water heater to resolve the problem. To reset the
water heater, press the Reset button.
For outdoor installation models, press the OK button
once and “RST”will be displayed on the LCD display.
If resetting the water heater does not solve the
problem, refer to the Troubleshooting section of this
manual or contact Technical Support at 1-800-519-
8794.
3.3 Viewing Basic Information
(Indoor Models Only)
To view information about the water heater, press
the Information button.
Press the + or – buttons to switch between the
information types.
Display Description
Flow rate in gallons per
minute (GPM).
Hot water outlet temperature
(OUT).
Cold water inlet temperature
(IN).
To exit information mode, press the Reset button.

13Operating the Water Heater
3.6 Setting the clock
1. Press the Preheat & Timer button for 2 seconds.
2sec
2. Adjust the minutes by pressing the Up or Down
Button.
Press the OK button to set the minutes.
or
3. Once the minutes are set, adjust the hour by
pressing the Up or Down button.
3.5 Entering Lock Mode
To prevent accidental pressing of the buttons and to
prevent children from adjusting the controller, you
can activate the Temperature Lock Mode.
To activate or deactivate Lock Mode, press the Lock
button for 2 seconds.
2sec
When Lock Mode is activated,
ƔThe Lock icon appears on the display.
ƔAll buttons except for Lock button are locked.
Note ƔResetting errors or alarms is still
available with Lock Mode activated.
ƔYou can change the settings from
the front panel with Lock Mode
activated.

14 Operating the Water Heater
2. Set the recirculation activation time by pressing
the Up or Down button.
or
Then, press the OK button to set the
deactivation time.
Note The recirculation timer settings are
divided in 30 minute increments.
3. Set the deactivation time by pressing the Up or
Down button.
or
4. Press the OK button to finish and save the
updated time.
3.7 Setting the Recirculation
timer
1. Press the Preheat & Timer button to set the
Recirculation timer while setting the clock.
Reservation Schedule #1 is ready to be set.
Note This feature is available only when
external circulating pumps are
connected and ON.

15Operating the Water Heater
3.8 Starting Recirculation
Press the Preheat & Timer button to start
recirculation immediately, regardless of the
reservation schedule.
“HEAT” appears for 4 seconds on the display and
then recirculation runs once.
During the recirculation, the preheating icon flashes
continuously.
Note ƔThis feature is available only when
external circulating pumps are
connected and ON.
ƔThis feature runs during the
recirculation time set on the front
panel which the remote controller is
connected to.
3.9 Canceling all timer settings
Press and hold the Preheat & Timer and OK button
simultaneously for 2 seconds.
“CLR”appears for 3 seconds and all timer settings
are canceled.
2sec
4. Press the OK button to save the timer setting.
Repeat these procedures for Reservation
Schedule Settings #2 and #3.
5. During the reservation schedule, the preheating
icon turns on and the Reservation area starts
flashing.
Note This is applied to A models with the
preheating function only.

16 Maintaining the Water Heater
4.1 Cleaning the Water Heater
CAUTION
Make sure the water heater is turned off and the
power supply is disconnected before cleaning
the water heater. The water heater may remain
hot for several minutes after it is turned off. To
prevent burns, wait until the water heater has
cooled down before cleaning.
To clean the water heater, wipe the outside with a
damp cloth. Use a non-acidic, non-abrasive cleaner
to remove any surface stains. The front panel is
moisture resistant, but it is not waterproof. Keep it as
dry as possible.
4.2 Draining the Water Heater
You need to drain the water heater before
performing maintenance tasks, such as cleaning the
inlet water filter, or to prevent the water heater from
freezing when it will not be used for an extended
period.
Refer to the“2.2 Parts of the Water Heater” on page
7 for details about part locations.
To drain the water heater:
1. Place a bucket under the water heater, to collect
the residual water inside the water heater.
2. Press the Power button on the front panel to
turn off the power to the water heater.
[Indoor Models]
[Outdoor Models with Remote Controller]
3. Close the gas valve.
Opened
Gas
Valve
Closed
4. Maintaining the Water Heater

17Maintaining the Water Heater
9. When the water is completely drained, reinsert
the cold water inlet filter, and then close the
water drain plug.
10. To refill the water heater follow the steps of
“Draining the Water Heater” in reverse.
4.3 Flushing the Heat Exchanger
CAUTION
Flushing the Heat Exchanger is a somewhat
complicated procedure. Read the following
instructions carefully before attempting this
procedure. If you are uncertain about any of the
steps in the procedure, contact an authorized
technician or licensed professional. Keep in
mind that improper maintenance can void your
warranty.
Refer to the“2.2 Parts of the Water Heater” on page
7 for details about part locations.
Before flushing the Heat Exchanger, gather the
following items:
ƔA bucket that is 5 gallons or larger
ƔCleaning solution diluted with water
Ɣ3 hoses
ƔA water circulation pump
4. Close the water supply valve on the inlet to the
water heater. If there is no valve, turn off the
water supply at the water main.
5. Open all hot water faucets completely. The
water that remains in the plumbing lines will
drain out.
6. Open the water drain plug.
Water Drain Plug
7. Remove the cold water inlet filter.
8. Allow the residual water to drain from the water
heater.

18 Maintaining the Water Heater
10. Rinse the cleaning solution from the water
heater:
a. Remove the free end of the drain tube from
the bucket and place it in the condensate
drain or laundry tub (wherever the water
heater drains).
b. Close the“B” valve and open the “D” valve. Do
not open the “C” valve yet.
c. Allow water to flow through the water heater
for 5minutes.
d. Close the“A”valve and open the “C” valve.
11. Disconnect all tubes.
12. Remove the cold water inlet filter from the water
heater and clean out any residue.
13. Reinsert the filter and ensure the filter cap is
securely tightened.
14. Reconnect the power supply to the Water
Heater.
15. Press the Power button on the front panel to
turn on the water heater.
To flush the Heat Exchanger:
A
A
B
B
C
C
D
D
Navien Easy valve Kit
Cold Water Line
Hot Water Line
Circulation Pump
Flushing Kit
1. Press the Power button on the front panel to
turn off the water heater.
2. Disconnect the power supply to the water
heater.
3. Close the “C” and “D” valves on the hot and cold
water lines.
4. Connect one tube to the “A”valve and place the
free end in the bucket.
5. Connect one of the tubes to the circulation
pump outlet and the cold water line at the“B”
valve.
6. Connect one tube to the circulation pump inlet
and place the free end in the bucket.
7. Pour the cleaning solution into the bucket.
8. Open both “A” and “B” valves.
9. Turn on the circulation pump and allow the
solution to circulate through the water heater
for at least 45minutes.

19Maintaining the Water Heater
4.5 Protecting the Water Heater
from Freezing
CAUTION
Damage due to freezing is not covered by the
Navien limited warranty.
ƔFreezing damage is most likely to occur due
to back drafting caused by negative pressure
in the building. This is not a manufacturing
defect, and therefore, Navien will not
warrant any damages due to freezing. The
installer is responsible for ensuring that
there is sufficient make-up air to avoid such
a situation and the owner is responsible for
ensuring that protection against freezing is
maintained.
ƔTo avoid freezing issues, we strongly
recommend the use of a direct vent exhaust
and intake system. Your installer should
ensure that the exhaust vent pipe and the air
intake pipe are both connected directly from
the collars on the top of the water heater
to the outdoors. This type of vent system
minimizes air movement within the water
heater.
ƔThis water heater has an optional recirculation
mode that is used for freeze protection. This
mode should prevent the water heater from
freezing, even if the intake air duct is not
vented directly.
ƔThe water heater is designed for indoor or
outdoor installation. However, it should not
be installed outdoors in areas that are prone
to freezing temperatures.
4.4 Cleaning the Inlet Water Filter
To clean the filter:
1. Drain the water heater. Refer to“4.2 Draining the
Water Heater” on page 16.
2. While the filter is removed, rinse it with clean
running water (cold) and, if necessary, scrub it
clean with a brush.
3. Reinsert and tighten the filter.
Cold Water
Inlet Filter
4. Refill the water heater. Refer to“4.2 Draining the
Water Heater” on page 16.

20 Maintaining the Water Heater
5. Check every few minutes to see if water is
running at the open faucet.
6. When the water starts flowing again, check the
water heater and piping for leaks. If you detect
any leaks or the water heater is not operating
properly, contact an authorized technician or
licensed professional.
CAUTION
If the unit will not be used immediately, close off
all gas and water shutoff valves, drain all of the
water out of the unit and the plumbing system
to prevent the unit and system from freezing,
and bleed the gas out of the gas line.
To ensure that the water heater does not freeze,
follow these guidelines:
ƔDo not unplug the power supply cord, except
for routine maintenance. The water heater
has a freeze protection function that requires
electricity. The freeze protection function will
operate regardless of whether or not the power is
turned on or off, as long as the electric supply is
still connected.
ƔDo not close the gas valve, except for routine
maintenance, as this will limit additional freeze
protection.
ƔIf the power or gas supplies must be
disconnected for an extended period, drain the
water heater. Freezing damage may occur if there
is a loss of power or an interruption in the gas
supply to the water heater.
If the water heater will not be used for an
extended period, drain the water heater.
If hot water will not flow and you suspect that the
water heater is frozen, follow these steps:
1. Press the Power button on the front panel to
turn off the water heater.
2. Close the gas valve.
Opened
Gas
Valve
Closed
3. Open the hot water faucet that is closest to the
water heater.
4. Use a hair dryer or a portable electric heater to
heat up both the primary and secondary Heat
Exchangers.