Navien NPE-180A2 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, ANSIZ223.1/NFPA 54 and/or CSA B149.1, Natural Gas and Propane Installation
Code.
When applicable, the installation must conform with the Manufactured Home Construction and
Safety Standard, Title 24 CFR, Part 3280 and/or CAN/CSA Z240 MH Series, Mobile Homes.
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.
* Lead Free
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.
* Lead Free
User’s Information Manual
NPE Condensing Water Heaters
Model NPE-180A2
NPE-210A2
NPE-240A2
NPE-180S2
NPE-210S2
NPE-240S2

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 8
3. Operating the Water Heater 9
3.1 Turning the Water Heater On or Off 9
3.2 Adjusting the Water Temperature 9
3.3 Resetting the Water Heater 10
4. Maintaining the Water Heater 11
4.1 Cleaning the Water Heater 11
4.2 Draining the Water Heater 11
4.3 Flushing the Heat Exchanger 12
4.4 Cleaning the Inlet Water Filter and
Recirculation Inlet Filter 13
4.5 Cleaning the Air Intake Filter 14
4.6 Protecting the Water Heater from Freezing15
5. Troubleshooting 16
5.1 Solving Basic Problems 16
5.2 Understanding Error Codes 17

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
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 electric switch; do not
use any phone in your building.
ƔImmediately call your gas supplier from
a neighbor’s phone. Follow the gas
supplier’s 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
This water heater 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 seconds
120 °F (49 °C) 10 minutes
100 °F (37 °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.
California law requires the following Prop 65
warning to be provided:
WARNING
Cancer and Reproductive Harm -
www.P65Warnings.ca.gov
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, consider using a lower
temperature setting.
ƔDo not leave children, 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 heater above
125 °F (52 °C), have a temperature-limiting
valve or mixing valve installed on the water
heater.

5Safety Information
WARNING
ƔDo not operate this water heater without
proper venting.
Doingsomayresultin 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
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.
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 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 and Canada 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 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.
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 thanits intended purpose, as described
in this manual.
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.
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.
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 NPE series water heater is available in 6 models:
NPE-180A2, NPE-180S2, NPE-210A2, NPE-210S2,
NPE-240A2 and NPE-240S2.
The main features are as follows:
ƔPotable domestic hot water, combination space
heating, and commercial applications
ƔMaximum temperature: 185 °F (85 °C)
ƔDual stainless steel Heat Exchangers with stainless
steel piping
ƔBuilt-in pump and 0.4 US gallon (1.5 liter) Buffer
Tank for internal or external recirculation (“A2”
model only)
2.2 Parts of the Water Heater
Exhaust
Gas Vent
Combustion
Air Intake
2.2.1 Bottom View
a
b
c
d
e
f
g
h
# Description Remark
a Pump Drain Port “A2” model only
b Gas Inlet
c Hot Water Outlet Connection
d Recirculation Inlet “A2” model only
e Condensate Water Clean-out
f Inlet Water Filter
g Cold Water Inlet Connection
hCondensate Drain
Connection
2. About the Water Heater

8 About the Water Heater
b
a
g
h
i
c
d
e
f
j
k
l
2.3 The Front Panel
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
Recirculation/
Space Heating
Displays recirculation
(Always On/Intelligent/
Weekly/HotButton) and
space heating (with
optional H2Air kit) status.
b
Combustion/Error
Displays combustion/
error status.
c
Gas
Displays when the unit is
configured for propane
gas.
d
Main/Sub
Displays whether the
water heater is a main
or a sub unit of the
cascade system.
e
Status/Flow
Displays the operation
status (including Stand-
by) and current flow rate.
f
Hot Water
Temperature Setting
Displays the hot water
temperature setting.
g
Menu button
Access to the Main menu
screen.
h
Back button
Access to the previous
screen.
i
OK button
Access to the selected
item.
j
Up button
Increases the
temperature setting,
parameter or moves up.
k
Down button
Decreases the
temperature setting,
parameter or moves
down.
l
Power button
Turns the water heater
on or off.

9Operating 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 ( ).
When the power is turned on for the first time, you
must complete the start-up wizard. The temperature
will appear on the front panel display after the
power is turned on.
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 97 -
110 °F (36 - 43 °C).
2. Press the Up button ( ) or the Down button
() 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.
3. Operating the Water Heater

10 Operating the Water Heater
3.3 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 Back button ( ).
If resetting the water heater does not solve the
problem, refer to“5. Troubleshooting”on page 16
or contact technical support at 1-800-519-8794.
Note The water heater will retain your
settings during a power outage.
You can adjust the temperature by 1 degree
increments as shown below, depending on the
temperature range:
Temperature range Adjusting the water
temperature
97 °F - 120 °F (Fahrenheit mode)
36 °C - 50 °C (Celsius mode)
1 °F or 0.5 °C
increments
120 °F - 140 °F (Fahrenheit
mode)
50 °C - 60 °C (Celsius mode)
1 °F or 0.5 °C
increments
The water heater will not provide hot water instantly
through the hot water faucet unless a recirculation
line has been installed from the furthest fixture back
to the water heater. For“A2”models, the unit must
be set to“external recirculation” mode.
3.2.1 Using Commercial Mode
To use water above 140 °F (60 °C) (up to 185 °F (85
°C)), you can use Commercial Mode.
Note ƔDetails for activating this mode are
included in the Installation Manual.
ƔThe commercial warranty applies
when this mode is used. Refer to the
Warranty for more details.

11Maintaining 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.
3. Close the gas valve.
Opened
Gas
Valve
Closed
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.
4. Maintaining the Water Heater

12 Maintaining the Water Heater
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
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
6. Remove the recirculation inlet filter from the
bottom of the water heater (“A2” model only).
Recirculation
Inlet Filter
(“A2”model
only)
Pump Drain Plug
(“A2”model only)
Cold Water
Inlet Filter
7. Open the pump drain plug (“A2”model only).
8. Remove the cold water inlet filter.
9. Allow the residual water to drain from the water
heater.
10. When the water is completely drained, reinsert
the recirculation inlet filter and the cold water
inlet filter, and then close the pump drain plug.
11. To refill the water heater follow the steps above
in reverse.

13Maintaining the Water Heater
4.4 Cleaning the Inlet Water Filter
and Recirculation Inlet Filter
To clean the filters:
1. Drain the water heater. Refer to“4.2 Draining the
Water Heater” on page 11.
2. While the filters are removed, rinse it with clean
running water (cold) and, if necessary, scrub it
clean with a brush.
Cold Water
Inlet Filter
Recirculation
Inlet Filter
(“A2”model
only)
3. Reinsert and tighten the filters.
Recirculation Inlet Filter
(“A2”model only)
Cold Water
Inlet Filter
4. Refill the water heater. Refer to“4.2 Draining the
Water Heater” on page 11.
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.
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.

14 Maintaining the Water Heater
5. Pull the filter out of the water heater.
6. Remove the filter from the plastic assembly and
clean it with a toothbrush and clean running
water.
7. Allow the filter to dry completely.
8. Reinsert the filter into the plastic assembly.
9. Place the filter assembly back into the water
heater and secure it with the screw.
10. Replace the front cover.
11. Reconnect the power supply to the water
heater.
12. Press the Power button ( ) on the front panel
to turn on the water heater.
4.5 Cleaning the Air Intake Filter
If the air intake filter becomes clogged by dust or
lint, the water heater will cease to operate and“Error
Code 110”will appear on the front panel display.
To properly maintain the water heater, you should
clean the air intake filter every 3-4 months.
To clean the air intake filter:
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. Remove the front cover of the water heater.
4. Remove the screw that secures the air intake
filter (the filter is located at the top left of the
water heater).

15Maintaining 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.
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.
4.6 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.
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 (“A2” model only).
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.

16 Troubleshooting
If resetting the water heater and attempting the remedies suggested below do not resolve the problem, contact
an authorized technician, a licensed professional, or Technical Support at 1-800-519-8794 for service instructions.
Problem Possible Cause(s) What to do
No water comes out when
the hot water tap is opened.
ƔIs the cold water inlet filter clean?
ƔIs an error code displayed on the
front panel?
ƔIs the water heater frozen?
ƔEnsure that the shut–off valves on
the hot and cold pipes are open.
ƔIf an error code is displayed, refer
to“5.2 Understanding Error Codes”
on page 17.
The water from the hot water
faucet is cold or turns cold
and stays cold.
ƔIs the cold water inlet filter clean?
ƔIs the hot water faucet open wide
enough draw at least 0.5gallons of
water per minute (GPM) through
the water heater?
ƔIs an error code displayed on the
front panel?
ƔIf there is an external recirculation
system installed, is there a check
valve on the recirculation return
line?
ƔClean the cold water inlet filter. See
“4.4 Cleaning the Inlet Water Filter
and Recirculation Inlet Filter” on
page 13.
ƔOpen the hot water faucet
completely.
ƔIf an error code is displayed, refer
to“5.2 Understanding Error Codes”
on page 17.
It takes too long for hot water
to reach the fixtures.
Are you using the external
recirculation mode?
Have a contractor install a
recirculation return line from the
furthest faucet back to the water
heater.
The water is not hot enough. Is the set temperature too low?
ƔCheck the water heater’s
temperature setting. Refer to“3.2
Adjusting the Water Temperature”
on page 9.
ƔCheck for cross plumbing between
the cold and hot water lines.
The water is too hot. Is the set temperature set too high?
Check the water heater’s temperature
setting. See“3.2 Adjusting the Water
Temperature”on page 9.
5. Troubleshooting
5.1 Solving Basic Problems
If you experience a problem with the water heater,
refer to the following chart for possible remedies.
Error codes that appear on the front panel display
are explained in the following section.
For minor problems, resetting the water heater may
resolve the issue. To reset the water heater, press the
Back button ( ) on the front panel.

17Troubleshooting
5.2 Understanding Error Codes
When an error code appears on the front panel, refer to the following chart for a definition and possible remedy
for the situation.
Error Code Reason Self-diagnostic / Action
E003 Ignition failure ƔEnsure that the main gas supply valve is open.
E004 False flame detection ƔEnsure that the electrical cord is properly grounded.
E012 Flame loss ƔClean the intake air filter. See page 14.
ƔEnsure that the electrical cord is properly grounded.
E016 Overheating of heat exchanger ƔClean the cold water inlet filter. See page 13.
ƔFlush the heat exchanger. See page 12.
E030
Exhaust overheating (the water heater
shuts down when the flue temperature
exceeds 149 °F (65 °C)
ƔClean the cold water inlet filter. See page 13.
ƔFlush the heat exchanger. See page 12.
E031 Overheating of burner Contact technical support at 1-800-519-8794.
E046 Abnormal operation: limit control Contact Technical Support at 1-800-519-8794.
E047 Exhaust thermostat: thermistor open
or short circuit Contact Technical Support at 1-800-519-8794.
E060 Abnormal operation: dual venturi Contact Technical Support at 1-800-519-8794.
E109 Abnormal operation: fan motor Clean the intake air filter. See page 14.
E110 Abnormal air pressure ƔEnsure that the exhaust pipe is free of obstructions.
ƔClean the intake air filter. See page 14.
E407 Hot water outlet: thermistor open or
short circuit Contact Technical Support at 1-800-519-8794.
E421 Cold water inlet1: thermistor open or
short circuit Contact Technical Support at 1-800-519-8794.
E432 Cold water inlet2: thermistor open or
short circuit Contact Technical Support at 1-800-519-8794.
E434 Abnormal operation: water adjustment
valve Contact Technical Support at 1-800-519-8794.
E438 Abnormal operation: circulation pump
(in case of installed AHU) Check if the circulation pump is operating properly.
E439 Abnormal operation: flow sensor Contact Technical Support at 1-800-519-8794.
E441 Hot water inlet2: thermistor open or
short circuit Contact Technical Support at 1-800-519-8794.
E445 Abnormal operation: Bypass mixing
valve Contact Technical Support at 1-800-519-8794.
E515 Abnormal operation: PCB Ensure that the electrical cord is properly grounded.
E517 Abnormal operation: DIP switch setting Contact Technical Support at 1-800-519-8794.
E593 Abnormal operation: front panel key Contact Technical Support at 1-800-519-8794.
E594 Abnormal operation: EEPROM Contact technical support at 1-800-519-8794.
E615 Abnormal operation: input and
memory Contact Technical Support at 1-800-519-8794.

18 Troubleshooting
Error Code Reason Self-diagnostic / Action
E736 Abnormal operation: cascade
communication Contact Technical Support at 1-800-519-8794.
E740
Abnormal operation: outdoor
temperature sensor (in case of installed
AHU)
Contact Technical Support at 1-800-519-8794.
E760 Flushing/service alarm Contact the installer to perform routine service.
E762 Vent pipe not properly inserted Contact Technical Support at 1-800-519-8794.
E773 Using the wrong gas Contact Technical Support at 1-800-519-8794.
E782 Abnormal operation: main panel
communication Contact Technical Support at 1-800-519-8794.
E785 Abnormal operation: flow switch/
sensor (in case of installed AHU) Contact Technical Support at 1-800-519-8794.
E788
Abnormal operation: Discrepancy with
the gas type on the panel DIP S/W
setting and the panel
Check the supplied gas type and match the gas type
setting on the panel DIP S/W and the panel.
If any of these remedies do not resolve the problem, contact Technical Support at 1-800-519-8794.

19Warranty
Warranty Period
Navien products come with a limited warranty
covering labor, parts and the heat exchanger. The
following warranty periods begin to run from the
date of original installation. The date of original
installation must be provided to Navien, and upon
request, proof of the original installation date must
also be provided to Navien. When the product is
installed in a new construction, the commencement
date shall be dated upon which the end-user takes
title to the property.
APPLICABLE WARRANTY PERIOD
Application Labor
Warranty
Parts
Warranty
Heat
Exchanger
Warranty
NPE Series
Water Heater
(Residential)
Standard
or Cont.-
Recirc.1 year 5 years 15 years
Uncont.-
Recirc.1 year 3 years 5 years
NPE Series
Water Heater
(Commercial
or Combi)
Standard
or Cont.-
Recirc.1 year 5 years 8 years
Uncont.-
Recirc.1 year 3 years 3 years
Combi refers to a combination potable water and space
heating application. Water heaters cannot be used in
space heating only applications.
Controlled-Recirculation:
Recirculation through the water heater is controlled by
either the water heater or an external aquastat.
Uncontrolled-Recirculation:
External pumps configured to circulate continuously
through the water heater are subject to the uncontrolled
recirculation warranty terms. An aquastat is the minimum
pump control requirement for DHW or storage tank
recirculation in order to maintain the full controlled
recirculation warranty.
Warranty Claim Procedures
To obtain warranty repair service, the end user or
homeowner must contact the original installer
of your Navien product. If the original installer
cannot be identified, the end user or homeowner
may contact Navien’s Technical Administration
Department at 1-800-519-8794. Proof of purchase
is required to obtain warranty service.
Warranty Service
At its option, Navien will replace the defective
component part(s) or heat exchanger, in accordance
with the terms of this Limited Warranty, if it fails
in normal use and service during the Applicable
Warranty Period identified above. The replacement
component part(s) must be Navien original factory
component part(s). Navien, at its sole discretion,
may replace the product with a new or refurbished
product of comparable quality and design. The
replacement component part(s) will be warranted
only for the unexpired portion of the original
component part’s Applicable Warranty Period.
Payment for labor in completing the warranty
service is subject to Navien’s prior written approval
and shall be subject to Navien’s schedule of
approved labor allowances.
Warranty Exclusions
Navien’s Limited Warranty shall be void in the event
of an occurrence of any of the following:
ƔImproper installation, failure to install in strict
compliance with the Installation Manual
procedures, installed by a non-licensed installer,
and installation in violation of applicable rules,
laws or building codes.
ƔProduct purchased through the internet,
other e-commerce channels, or any installer
that obtained the Product from a supplier or
distributor not authorized by Navien.
ƔFailure to perform regular maintenance,
misuse, operation at settings other than those
recommended or specified, non-compliance with
instructions or guidelines set forth in the User’s
Operation Manual.
ƔModification or alteration of the Product in any
manner, including but not limited to, removal
of any component or part, addition of any non-
approved components, relocating or moving the
Product from its original installation site, or any
accidental or intentional damage to the Product.
ƔInstallation for non-recommended uses.
ƔAny damage caused by local adverse conditions
including but not limited to hard water deposits,
lime or mineral build-up, operating in corrosive
atmospheric elements.
ƔDamage or problems caused by gas flow issues,
electrical surges, flooding, fire, abnormal external
temperature, and any other cause of damage not
directly caused by a manufacturing defect.
LIMITED WARRANTY NAVIEN, INC.

20 Warranty
total liability for any claim arising hereunder shall
not exceed the purchase price which you paid for
the Product. NAVIEN SHALL NOT IN ANY EVENT BE
LIABLE FOR INDIRECT, SPECIAL, CONSEQUENTIAL
OR LIQUIDATED DAMAGES OR PENALTIES,
INCLUDING CLAIMS FOR LOST REVENUE, PROFITS
OR BUSINESS OPPORTUNITIES, EVEN IF NAVIEN HAD
OR SHOULD HAVE HAD ANY KNOWLEDGE, ACTUAL
OR CONSTRUCTIVE, OF THE POSSIBILITY OF SUCH
DAMAGES.
ƔInstaller’s failure to fully comply with the Warranty
Service and Return Policy procedures previously
provided to Installer and as is available on
Navien’s website. Such policies include but are
not limited to the Installer’s failure to first contact
Navien Technical Support while in front of the
product for purposes of trouble shooting the
identified problem or issue.
ƔUse of the NPE Series Water Heater for space
heating only purposes shall void the warranty.
ƔPerformance problems caused by improper
sizing of the water heater, the gas supply line, the
venting connection, combustion air openings,
electric service voltage, wiring, fusing or any other
components, parts or specifications.
ƔImproper conversion from natural gas to LP gas or
LP gas to natural gas or attempt to operate with a
type of gas not specified for the water heater.
ƔAny damage, malfunction or failure caused by
abuse, negligence, alteration, accident, fire, flood,
freezing, wind, lightning and other acts of God.
ƔOperating, using or storing the water heater
in a corrosive or contaminated atmosphere or
environment.
ƔOperating the water heater at water temperatures
outside the factory calibrated temperature limits
and/or exceeding the maximum setting of the
high limit control.
ƔOperating the water heater when it is not
supplied with potable water at all times.
ƔSubjecting the heat exchanger to pressures or
firing rates greater or lesser than those shown on
the rating plate.
ƔInstallation at any location outside the United
States and Canada.
ƔRemoval or alteration of the rating plate.
Other Terms: This Limited Warranty is subject
further to the terms and conditions set forth herein
and as may be further specified in the Terms and
Conditions page located on Navien’s website at
www.navieninc.com. WITH THE EXCEPTION OF
THIS LIMITED WARRANTY, NAVIEN DISCLAIMS
ANY OBLIGATION OR LIABILITY WITH RESPECT TO
THE PRODUCTS OR THEIR SALE AND USE, AND
NAVIEN NEITHER ASSUMES NOR AUTHORIZES THE
ASSUMPTION OF, ANY OBLIGATION OR LIABILITY
IN CONNECTION WITH THE PRODUCTS. THIS
DISCLAIMER INCLUDES ANY OTHER WARRANTIES,
EXPRESS, IMPLIED OR STATUTORY RESPECTING
THE PRODUCTS OR ANY PARTS OR COMPONENTS
THEREOF, INCLUDING, BUT NOT LIMITED TO, ANY
IMPLIED WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE. Navien’s