Navien NPE-180A2 User manual

Getting Service
If your water heater requires service, you have several options for getting service:
●Contact Technical Support at 1-800-519-8794 or on the website: www.navieninc.com.
●For warranty service, always contact Technical Support first.
●Contact the technician or professional who installed your water heater.
●Contact a licensed professional for the affected system (for example, a plumber or electrician).
When you contact Technical Support, please have the following information at hand:
●Model number
●Serial number
●Date purchased
●Installation location and type
●Error code, if any appears on the front panel display
Navien, Inc.
800.519.8794 www.navieninc.com
20 Goodyear, Irvine, CA 92618
Installation Manual
NPE Condensing Water Heaters
THE LEADER IN CONDENSING TECHNOLOGY
Version: 1.0 (Feb. 2021)
20049624A

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.
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, Manufactured Home.
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
Installation Manual
NPE Condensing Water Heaters
Model NPE-180A2
NPE-210A2
NPE-240A2
NPE-150S2
NPE-180S2
NPE-210S2
NPE-240S2

2Contents
6. Operating the Water Heater 80
6.1 Turning the Water Heater On or Off 80
6.2 Start-Up Wizard 80
6.3 Adjusting the Water Temperature 81
6.4 Accessing the Basic Menu Items 82
6.5 Accessing Advanced Menu Items 88
7. Appendixes 98
7.1 Gas & High Altitude Conversion 98
7.2 Technical Data 106
7.3 Wiring Diagram 109
7.4 Ladder Diagram 110
7.5 Component Assembly Diagrams and
Parts Lists 111
7.6 Installation Checklist 124
7.7 Navien HAir Add-on Controller Kit
(Optional) 126
7.8 AHU Application with RS-485
Communication (optional) 128
7.9 Requirements for the State of
Massachusetts 129
1. Safety Information 3
2. About the Water Heater 6
2.1 Items Included 6
2.2 Accessories 6
2.3 Specifications 7
2.5 Components 9
2.6 Dimensions 12
2.7 Rating Plate 14
3. Installing the Water Heater 15
3.1 Choosing an Installation Location 15
3.2 Mounting the Water Heater to the Wall 18
3.3 Connecting the Gas Supply 19
3.4 Connecting the Water Supply 24
3.5 Connecting the Condensate Drain 37
3.6 Venting for Combustion Air 40
3.7 Connecting the Power Supply 58
3.8 Setting the DIP Switches 58
4. Installing a Cascade System 60
4.1 Connecting Water Supplies 60
4.2 Connecting the Communication Cables 62
5. Installing a Common Vent System 64
5.1 About the Common Vent System 64
5.2 Navien Common Vent Collar Kit (Back-
draft Damper) 70
5.3 Starting the Common Vent System 71
5.4 Connecting and Terminating the Vent
Pipe 75
5.5 Installing a Condensate Drain 76
5.6 Setting up the Common Vent System 77
5.7 Common Vent Termination Clearances 78
5.8 Maintenance 79
Contents

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.
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.
DANGER
If you smell gas:
●Do not try to light any appliance.
●Do not touch any electrical switches or use
landline phones.
●From a neighbor’s phone, call your gas
provider and follow their instructions.
●If you cannot reach your gas provider, call the
fire department.
Do not use or store flammable products,
such as gasoline, solvents, or adhesives in
the same room or area as the water heater.
●The water heater has a main burner flame
that can turn on at any time and can ignite
flammable vapors. Vapors from flammable
liquids can explode and catch fire, causing
death or severe burns.
●Vapors cannot be seen and are heavier than
air. They can travel long distances along the
ground and can be carried from other rooms
to the water heater’s main burner flame by air
current.
●Keep all flammable products far away from
the water heater and store them in approved
containers. Keep the containers closed tightly
and out of the reach of children and pets.
1. Safety Information

4Safety Information
California law requires the following Prop 65
warning to be provided:
WARNING
Cancer and Reproductive Harm -
www.P65Warnings.ca.gov
CAUTION
●Do not turn on the water heater unless the
water and gas supplies are fully opened.
Doing so may damage the water heater.
●Do not turn on the water if the cold water
supply shut-off valve is closed.
Doing so may damage the water heater.
●Do not use this water heater for anything
other than its intended purpose, as
described in this manual.
●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. Verify proper operation after
servicing.
●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
water heater.
●This 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.
WARNING
●Do not store or use gasoline or other
flammable liquids near this water heater.
Doing so may result in fire or explosion.
●Do not place combustibles, such as
newspapers or laundry, near the water
heater 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 water heater or venting system,
including the vent termination.
Doing so may result in fire or explosion.
●Do 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.
●Do 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.
●Do not operate this water heater without
proper venting.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may result
in property damage, personal injury, or death.
●Do not touch the power cord or internal
components of the water heater with wet
hands.
Doing so may result in electric shock.

5Safety 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 seconds
120°F (49°C) 10 minutes
100°F (37°C) very low scald risk
DANGER
HOT
BURN
To prevent burns:
●Use the lowest operating temperature setting
necessary to provide comfortably-hot water.
●If your household has children or elderly or
disabled residents, consider using a lower
temperature setting.
●Do not leave children, the elderly, or disabled
persons unsupervised.
●Do not allow small children to play
unsupervised in the bathroom.
●Do not allow anyone to change the water
temperature while hot water is running.
●Read all the instructions in this manual
carefully before changing the temperature
setting.
●Feel the water before using it on children, the
elderly, or the disabled.
●If 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.

6About the Water Heater
2.1 Items Included
When you open the box, you will find the following
items with the water heater. Check the box for each of
the following items before installing the water heater.
WARNING
Ifthe information in these instruc tions is not followedexactly, a re or explosion may
result,causing property damage, personal injury or death.
Donot storeor use gasolineor other ammablevapors and liquids in the vicinity of this or any
otherappliance.
Whattodo if you smell gas
●
Donot try to light any appliance.
●
Donot touch any electricalswitch; do not useany phone inyour building.
●
Immediatelycall your gas supplier from a neighbor’sphone. Followthe gassupplier’sinstructions.
●
Ifyou cannot reach your gas supplier,call the re department.
Installationand service must be performed by a qualiedinstaller,serviceagencyorthe gas
supplier.
Theinstallationmust conform withlocal codesor, inthe absenceof localcodes,theNational
FuelGasCode, ANSI Z223.1/NFPA54 and/orCSA B149.1, NaturalGas andPropaneInstallation
Code.
Whenapplicable,the installation must conformwith the ManufacturedHomeConstructionand
SafetyStandard,Title 24 CFR, Part 3280and/or CAN/CSAZ240 MH Series, MobileHomes.
*Lead Free
Keepthis manual near this waterheater for future
referencewhenevermaintenanceorserviceis required.
*Thewetted surface of thisproduct contactedby
consumablewatercontains lessthan one quarter of
onepercent(0.25%) oflead by weight.
*Lead Free
InstallationManual
NPECondensing WaterHeaters
Model
NPE-180A2
NPE-210A2
NPE-240A2
NPE-180S2
NPE-210S2
NPE-240S2
Installation Manual Quick Installation
Manual
Wall Mounting Bracket Tapping Screws &
Anchors
2 in Vent Termination
Caps 2 in Wall Flanges
Spare Parts
High Altitude
Conversion Kit
(Natural Gas Only)*
Propane
Conversion Kit*
*High Altitude Conversion kit and Propane Conversion kit
are attached to the inside of Product’s case.
2.2 Accessories
The following optional accessories are available for
the water heater:
Remote Controller Plumb Easy Valve Set
with PRV
NPE-A2 Plumb Easy
3 Valve Set
(for recirculation)
Condensate
Neutralizer
Ready-Link
Communication Cable Outdoor Vent Kit
3 in Wall Flanges &
Vent termination Caps
External Pump
Connector
(<150 W, 1.5 A)
HAir Add-on
Controller Kit
Navi-Link
(Wi-Fi Control System)
Ready-Link Rack Ready-Link Manifold
Gas Conversion Kit HotButton Push
Button
HotButton Wall Plate Pipe Cover
2. About the Water Heater

7About the Water Heater
2.3 Specifications
The following table lists the specifications for the water heater. Additional specifications about water, gas,
electric, and air supplies (venting) appear in the Installation section.
Item
NPE-150S2 NPE-180A2 NPE-180S2 NPE-210A2 NPE-210S2 NPE-240A2 NPE-240S2
Heat
Capacity
(Input)
Natural Gas,
Propane Gas
18,000-
120,000
BTU/H
10,000-150,000 BTU/H 12,000-180,000 BTU/H 13,300-199,900 BTU/H
Uniform
Energy
Factor
UEF (for NG & LP) 0.93 0.95 0.96 0.95 0.96 0.95 0.96
Flow Rate
(DHW)
35 °F (19 °C)
Temp Rise
6.8 GPM
(25.8 L/m) 8.4 GPM (32 L/m) 10.1 GPM (38 L/m) 11.2 GPM (42 L/m)
45 °F (25 °C)
Temp Rise
5.3 GPM
(20 L/m) 6.5 GPM (25 L/m) 7.8 GPM (30 L/m) 8.7 GPM (33 L/m)
67 °F (36 °C)
Temp Rise
3.4 GPM
(13 L/m)
4.3 GPM
(16 L/m)
4.4 GPM
(17 L/m)
5.1 GPM
(19 L/m)
5.3 GPM
(20 L/m)
5.6 GPM
(21 L/m)
5.8 GPM
(22 L/m)
Dimensions 17.3 in (W) x 27.4 in (H) x 13.2 in (D)
Weight 62 lbs
(28 kg)
73 lbs
(33 kg)
68 Ibs
(31 kg)
77 Ibs
(35 kg)
73 lbs
(33 kg)
77 Ibs
(35 kg)
73 lbs
(33 kg)
Installation Type Indoor or Outdoor Wall-Hung
Venting Type Forced Draft Direct Vent
Ignition Electronic Ignition
Water Pressure 15-150 PSI
Natural Gas Supply Pressure
(from source) 3.5 in WC-10.5 in WC
Propane Gas Supply Pressure
(from source) 8 in WC-13in WC
Natural Gas Manifold Pressure
(min-max)
–0.04 in WC -
–0.40 in WC –0.03 in WC - –0.55 in WC –0.03 in WC - –0.76 in WC –0.03 in WC - –0.96 in WC
Propane Gas Manifold Pressure
(min-max)
–0.03 in WC -
–0.40 in WC –0.02 in WC - –0.55 in WC –0.02 in WC - –0.76 in WC –0.02 in WC - –0.96 in WC
Minimum Flow Rate 0.5 GPM (1.9 L/m), < 0.01 GPM (0.04 L/m) option for “A2”models*
Connection
Sizes
Cold Water Inlet 3/4in NPT
Hot Water Outlet 3/4in NPT
Gas Inlet 3/4in NPT
Power
Supply
Main Supply 120 V AC, 60 Hz
Maximum Power
Consumption 200 W (max 2 A), 350 W (max 4 A) with external pump connected
Materials
Casing Cold Rolled Carbon Steel
Heat Exchangers Primary Heat Exchanger: Stainless Steel
Secondary Heat Exchanger: Stainless Steel
Venting
Exhaust 2 in or 3 in PVC, CPVC, Approved Polypropylene
2 in or 3 in Special Gas Vent Type BH (Class II, A/B/C)
Intake 2 in or 3 in PVC, CPVC, Approved Polypropylene
2 in or 3 in Special Gas Vent Type BH (Class II, A/B/C)
Vent Clearances 0 in to combustibles
Safety
Devices
Flame Rod, APS, Ignition Operation Detector, Water Temperature High Limit Switch, Exhaust Temperature High
Limit Sensor, Power Surge Fuse, Burner High Limit Fuse, Vent Installation Detector (VID)
* Available for “A2”models configured in an optional ComfortFlow recirculation mode. Energy consumption will increase when
the system is configured for recirculation.

8About the Water Heater
b
a
g
h
i
c
d
e
f
j
k
l
2.4 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.

9About the Water Heater
2.5 Components
The following diagram shows the key components of the water heater. Component assembly diagrams and
particular parts lists are included in the Appendixes.
Intake Air Duct
Intake Air Filter
Exhaust Duct
Vent Installation
Detector
Exhaust Limit
Temperature Sensor
Exhaust Body
Burner High Limit Fuse
Ignition Transformer
Burner
Igniter/Flame Rod
Primary Heat
Exchanger
Secondary Heat
Exchanger
Flow Sensor
Condensate Trap
Front Panel
PCB Box
Water Adjustment
Valve
Water Inlet Filter
Condensate Drain
Cap
Fan Motor
Dual Venturi
Gas Pipe
Air Pressure Sensor
(APS)
Buffer Tank
Circulation Pump
Gas Valve
DHW Supply Fitting
Gas Inlet Fitting
2-Way Valve
Recirculation Inlet
Fitting
[NPE-180A2/ 210A2/ 240A2]

10 About the Water Heater
Intake Air Duct
Intake Air Filter
Exhaust Duct
Vent Installation
Detector
Exhaust Limit
Temperature Sensor
Exhaust Body
Burner High Limit Fuse
Ignition Transformer
Burner
Primary Heat
Exchanger
Secondary Heat
Exchanger
Water Adjust Valve
(Built in Flow Sensor)
Condensate Trap
Front Panel
PCB Box
Mixing Valve
Water Inlet Filter
Condensate Drain
Cap
Fan Motor
Single Venturi
Gas Pipe
Air Pressure Sensor
(APS)
Gas Valve
DHW Supply Fitting
Gas Inlet Fitting
Igniter/Flame Rod
[NPE-150S2]

11About the Water Heater
Intake Air Duct
Intake Air Filter
Exhaust Duct
Vent Installation Detector
Exhaust Limit
Temperature Sensor
Exhaust Body
Ignition Transformer
Burner High Limit Fuse
Burner
Primary Heat
Exchanger
Igniter/Flame Rod
Secondary Heat
Exchanger
Water Adjust Valve
(Built in Flow Sensor)
Condensate Trap
Front Panel
PCB Box
Mixing Valve
Water Inlet Filter
Condensate Drain
Cap
Fan Motor
Dual Venturi
Gas Pipe
Gas Valve
Air Pressure Sensor
(APS)
DHW Supply Fitting
Gas Inlet Fitting
[NPE-180S2/ 210S2/ 240S2]

12 About the Water Heater
2.6 Dimensions
The following diagrams show the dimensions of the water heater and the table lists the supply connections.
27.4 in (695 mm)
28.8 in (731 mm)
Supply Connections
Description Diameter
AAir Intake 2 in
BExhaust Gas Vent 2 in
CHot Water Outlet
3
/
4
in
DGas Inlet
3
/
4
in
ERecirculation Inlet
3
/
4
in
FCondensate Outlet
1
/
2
in
GCold Water Inlet
3
/
4
in
Overhead View
3 in (77 mm)
6.7 in (170 mm)
4.5 in (115 mm)
0.4 in (10 mm)
1.5 in (38 mm) 14.3 in (364 mm)
2.6 in (67 mm)
AB
Supply Connections
13.2 in (336 mm)
2.3 in (60 mm) 3.0 in (77 mm) 8.3 in (212 mm)
17.3 in (440 mm)
2.4 in (61 mm)
2.4 in (61 mm)
CD E F G
6.5 in (166 mm)
[NPE-180A2/ 210A2/ 240A2]

13About the Water Heater
27.4 in (695 mm)
28.8 in (731 mm)
Supply Connections
Description Diameter
AAir Intake 2 in
BExhaust Gas Vent 2 in
CHot Water Outlet
3
/
4
in
DGas Inlet
3
/
4
in
ECondensate Outlet
1
/
2
in
FCold Water Inlet
3
/
4
in
Overhead View
3 in (77 mm)
6.7 in (170 mm)
4.5 in (115 mm)
0.4 in (10 mm)
1.5 in (38 mm) 14.3 in (364 mm)
2.6 in (67 mm)
AB
Supply Connections
13.2 in (336 mm)
2.4 in (61 mm)
CE FD
2.3 in (60 mm) 11.3 in (289 mm)
17.3 in (440 mm)
2.4 in (61 mm)
6.5 in (166 mm)
[NPE-150S2/180S2/210S2/ 240S2]

14 About the Water Heater
2.7 Rating Plate
Water Heaters come from the factory configured for use with Natural Gas (NG). Before starting the installation,
check the rating plate located on the side of the water heater to ensure that the water heater matches the
gas type, gas pressure, water pressure, and electrical supply available in the installation location. If the water
heater does not match each of these ratings, do not install the water heater. If conversion to Propane Gas is
required, the included Propane conversion kit must be used.
WARNING
●Be sure the gas type and electricity voltage match the rating plate. Using a different gas type will cause
abnormal combustion and water heater malfunction.
●Using abnormally high or low AC voltage may cause abnormal operation, and may reduce the life
expectancy of this product.

15Installing the Water Heater
3.1 Choosing an Installation
Location
When choosing an installation location, you
must ensure that the location provides adequate
clearance for the water heater, adequate venting
and drainage options, and sufficient access to gas,
water, and electrical supplies. Carefully consider
the following factors when choosing an installation
location:
CAUTION
Review all of the installation information in this
manual before starting installation. Consider
all the requirements for venting, piping,
condensate removal, and wiring.
WARNING
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.
About Water Quality
Proper maintenance of the water heater is required
when water quality does not meet EPA standards.
Damage caused by poor water quality is not
covered under warranty. The following table shows
the maximum contaminant levels allowed, based
on the EPA National Secondary Drinking Water
Regulations (40 CFR Part 143.3). If you suspect that
your water is contaminated in any way, discontinue
use of the water heater and contact an authorized
technician or licensed professional.
Contaminant Maximum Allowable Level
Total Hardness Up to 200 mg/l (12 grains/gallon)
Aluminum 0.05 to 0.2 mg/l
Chloride Up to 250 mg/l
Copper Up to 1.0 mg/l
Iron Up to 0.3 mg/l
Manganese Up to 0.05 mg/l
pH 6.5 to 8.5
Sulfate Up to 250 mg/l
Total
Dissolved
Solids (TDS)
Up to 500 mg/l
Zinc Up to 5 mg/l
Chlorine Up to 4 mg/l
If your local water is hard, please review the
following recommended treatment and flushing
guidelines.
Hardness Level Treatment
Method
Flush
Frequency*
Soft 0-4 grains/gal
(0-60 mg/L) None
None
Moderately
Hard
4-7 grains/gal
(61-120 mg/L)
Water
Softener**
or Navien
PeakFlow is
Recommended
Once/Year
Hard 7-9 grains/gal
(121-160 mg/L)
Residential:
Once/Year
Commercial:
Twice/Year
Very Hard 9-12 grains/gal
(161-200 mg/L)
Water
Softener**
or Navien
PeakFlow
is HIGHLY
Recommended
Extremely
Hard
>12 grains/gal
(200 mg/L)
Water
Softener**
or Navien
PeakFlow is
Required
* Flushing is recommended if a treatment device is
not installed. This procedure should be performed
using white vinegar or solutions that are specifically
formulated for use on tankless water heaters.
**Check local codes for any restrictions on use of water
softeners.
3. Installing the Water Heater

16 Installing the Water Heater
Adequate Venting and Ventilation
Select a location that requires minimal venting.
Consider venting restrictions caused by windows,
doors, air intakes, gas meters, foliage, and other
buildings. For more information about venting, refer
to “3.6.1 Venting the Water Heater” on page 41.
To ensure adequate venting and ventilation, follow
these guidelines:
●Maintain proper clearances from any openings in
the building.
●Install the water heater with a minimum clearance
of 12 in
(300 mm) above an exterior grade or as required
by local codes.
●Maintain a minimum clearance of 4 ft (1.2 m) from
heating and cooling vents.
●Do not enclose the vent termination.
●Install the exhaust vent in an area that is free from
obstructions and does not allow the exhaust to
accumulate.
●Do not install the water heater where moisture
from the exhaust may discolor or damage walls.
●Do not install the water heater in bathrooms,
bedrooms, or any other occupied rooms that are
normally kept closed or that are not adequately
ventilated.
Proximity to Fixtures and Appliances
Install the water heater near fixtures that deliver
or use hot water, such as bathroom, kitchen,
and laundry room faucets. Select a location that
minimizes the water piping required between major
fixtures. If the distances are long or if the water
heater requires “instant“ hot water, we recommend
running a recirculation line back to the water heater
from the furthest fixture. Insulate as much of the hot
water supply and recirculation lines as possible. For
more information about the water supply, refer to
“3.4 Connecting the Water Supply” on page 24.
Access to Utilities
●Water – the installation location should be near
where the domestic water supply enters the
building.
●Gas – the installation location should be near
where the gas supply enters the building.
●Electricity – the installation location should
be near where the electrical supply enters the
building.
Adequate Drainage
The water heater produces a significant amount
of condensate during operation. The water heater
should be located near a suitable drain and where
damage from a possible leak will be minimal.
Installing the water heater in a location without a
drain will void the warranty and Navien will not be
responsible for water damages that occur as a result.
For more information about condensate drainage,
refer to “3.5 Connecting the Condensate Drain”on
page 37.
The water heater must be located in an area where
leakage of the unit or connections will not result in
damage to the area adjacent to the appliance or to
lower floors of the structure. When such locations
cannot be found, installation of an adequately
drained drain pan under the water heater is
highly recommended. When installing the drain
pan, ensure that the installation does not restrict
combustion air flow.

17Installing the Water Heater
●In commercial locations, do not install the water
heater in areas with greasy fumes or heavy
amounts of steam or take measures to prevent
fumes and steam from entering the water heater.
High Elevation Installations
This unit may be installed at elevations up to 10,100
ft (3,078 m) for use with natural gas and propane
gas. The Panel Setting should be set as described in
"Setting Up the Altitude" on page 59.
Natural gas units require the use of a high altitude
conversion kit if installed at an elevation of 5,400 ft
(1,646 m) or higher.
CAUTION
Follow the instructions in the guide provided
with the high altitude conversion kit when
replacing with the kit's gas orifice.
Failure to follow the instructions may result in
property damage, personal injury, or death.
Coastal Installations
For installations in sea or marine environments, the
salty air can cause corrosion to the water heater. The
water heater should be protected and enclosed to
minimize exposure to the corrosive atmosphere.
Damage due to a corrosive environment is not
covered under warranty.
Operating Temperature
The ambient temperature at the installation location
must be above 32˚F (0˚C) and below 120˚F (49˚C).
Adequate Installation Clearances
Install the water heater in an area that allows
for service and maintenance access to utility
connections, piping, filters, and traps. Based on the
installation location, ensure the following clearances
are maintained:
Clearance
from:
Indoor
Installation
Outdoor
Installation
Top 9 in (229 mm)
minimum
36 in (900 mm)
minimum
Back 0.5 in (13 mm)
minimum
0.5 in (13 mm)
minimum
Front 4 in (100 mm)
minimum
24 in (600 mm)
minimum
Sides 3 in (76 mm)
minimum
3 in (76 mm)
minimum
Bottom 12 in (300 mm)
minimum
12 in (300 mm)
minimum
Clean, Debris and Chemical-Free
Combustion Air
●Do not install the water heater in areas where
dust and debris may accumulate or where hair
sprays, spray detergents, chlorine, or similar
chemicals are used.
●Do not install the water heater in areas where
gasoline or other flammables are used or stored.
●Ensure that combustible materials are stored
away from the water heater and that hanging
laundry or similar items do not obstruct access to
the water heater or its venting.
Note The combustion air must be free
of flammable vapors or corrosive
chemical fumes. Common
corrosive chemical fumes to
avoid include fluorocarbons and
other halogenated compounds
such as Freon, trichloroethylene,
perchloroethylene, chlorine, all of
which can be found in refrigerants
or solvents. When these chemicals
burn, they produce acids that
corrode the stainless steel heat
exchanger, gaskets, and the flue
and vent system.

18 Installing the Water Heater
To mount the water heater to the wall:
1. Affix the bracket securely to the wall and ensure
that it is level and that it can support the weight
of the water heater.
2. Align the grooves on the back of the water
heater with the tongues on the mounting
bracket and hang the water heater on the
bracket.
When mounted with the mounting bracket, the
water heater will have a
5
/
8
in (16 mm) clearance
from the back of the wall.
3. Install two set screws through the bracket at the
bottom of the water heater to secure the water
heater on the wall.
3.2 Mounting the Water Heater to
the Wall
Navien water heaters come with an upper mounting
bracket that is pre-drilled at 16 in on center for easy
installation on standard wall studs. If the strength
of the wall is insufficient or if the framing is non-
standard or uneven, reinforce the area before
installing the water heater.
Note Avoid installation on common walls as
the unit will make some operational
noises while it is running.
WARNING
●The water heater is heavy. Always lift the
unit with assistance. Be careful not to drop
the water heater while lifting or handling it
to avoid bodily injury or damage to the unit.
●Do not rest the water heater on the bottom
end after removing it from the shipping
carton. Doing so may result in excessive
pressure on protruding pipes and cause
product damage. If you must put the water
heater down, lay it on its back or put it inside
the protective shipping base.
●Install the water heater in the upright, vertical
position. Installation in any other orientation
will result in improper water heater operation
and property damage, and could result in
serious personal injury or death.
CAUTION
●Ensure that the structure of the installation
location is sturdy enough to support the full
weight of the installed water heater, including
the water contained in the heat exchanger
and related piping.
●The wall must be vertical, and it must be
capable of carrying the weight of the water
heater.
●Do not mount the water heater to dry wall
that has not been reinforced.

19Installing the Water Heater
Navien recommends connecting the water heater as
the first water heater downstream of the gas meter,
to ensure a sufficient gas supply.
The water heater is
recommended to be
the first appliance to
be connected to the
gas supply line.
Gas Supply Line
Gas Meter’s Capacity ≥ Total Gas
Capacity of Connected Appliances
3.3 Connecting the Gas Supply
WARNING
●Before connecting the gas supply, determine
the gas type and pressure for the water heater
by referring to the rating plate. Use only
the same gas type indicated on the rating
plate. Using a different gas type will result
in abnormal combustion and malfunction
of the water heater. Gas supplies should be
connected by a licensed professional only.
●To avoid damaging the connectors on
the water heater, use two wrenches when
tightening pipings to the water heater. Use
one wrench to prevent the connector at the
water heater from turning, and use the other
wrench to tighten the connection. Damaged
connectors may result in system leaks.
●Properly support the piping with hangers. Do
not allow the piping to be supported by the
water heater or its accessories.
●Ensure that the gas piping is protected
from physical damage and freezing, where
required. Failure to follow these instructions
could result in gas leakage, and result in fire,
explosion, property damage, severe personal
injury, or death.
●The appliance and its gas connection must
be leak tested before placing the appliance in
operation.
●To avoid danger from explosion and fire, do
not use flame to check for a gas leak. Perform
a bubble test on the joints to check for gas
leaks. If a leak exists, bubbles will form at
the leaking joint. A gas leak could result in
substantial property damage, severe personal
injury, or death.
●This water heater cannot be converted from
natural gas to propane or vice versa without
a Navien gas conversion kit. Do not attempt a
field conversion of this water heater without a
Navien gas conversion kit. Doing so will result
in dangerous operating conditions and will
void the warranty.