Navien NPE-180A2 User manual

ALWAYS read and follow this manual completely before using
the water heater. Save for future reference.
Tested and Certified to NSF/ANSI 372 for lead free* compliance.
* The wetted surface of this product contacted by consumable
water contains less than one quarter of one percent (0.25%)
of lead by weight.
Installation Manual
NPE Condensing Water Heaters
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 moving vehicles as it will
result in a Carbon Monoxide Poisoning Hazard.
Model NPE-180A2
NPE-210A2
NPE-240A2
NPE-180S2
NPE-210S2
NPE-240S2
NPE-150S2
NPE-150S2
Excluded
ENERGY STAR
Certied

2Contents
6. Installing a Common Vent System 73
6.1 About the Common Vent System 73
6.2 Navien Common Vent Collar Kit (Back-
draft Damper) 79
6.3 Starting the Common Vent System 80
6.4 Connecting and Terminating the Vent
Pipe 84
6.5 Installing a Condensate Drain 85
6.6 Setting up the Common Vent System 86
6.7 Common Vent Termination Clearances 86
6.8 Maintenance 87
7. Operating the Water Heater 89
7.1 Turning the Water Heater On or Off 89
7.2 Start-Up Wizard 89
7.3 Adjusting the Water Temperature 90
7.4 Accessing the Basic Menu Items 91
7.5 Accessing Advanced Menu Items 97
8. Appendixes 107
8.1 Gas & High Altitude Conversion 107
8.2 Flushing the Heat Exchanger 115
8.3 Technical Data 117
8.4 Wiring Diagram 120
8.5 Ladder Diagram 121
8.6 Component Assembly Diagrams and
Parts Lists 122
8.7 Installation Checklist 135
8.8 Navien HAir Add-on Controller Kit
(Optional) 137
8.9 AHU Application with RS-485
Communication (optional) 139
8.10 Requirements for the State of
Massachusetts 140
1. Important Safety Information 3
2. About the Water Heater 6
2.1 Included Items 6
2.2 Accessories 6
2.3 Specifications 7
2.4 The Front Panel 8
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 25
3.5 Connecting the Condensate Drain 38
3.6 Venting for Combustion Air 41
3.7 Connecting the Power Supply 59
3.8 Setting the DIP Switches 60
4. Configuring the Remote Controller
System 62
4.1 Included Items 62
4.2 Accessories 62
4.3 Connecting the Extension Cable 62
4.4 Attaching the Wall Mounting Bracket 62
4.5 Remote Controller 63
4.6 Multi Remote Controller System 64
4.7 Entering Lock Mode 66
4.8 Setting the Clock 66
4.9 Setting the Recirculation Timer 67
4.10 Starting Recirculation 68
4.11 Canceling all Timer Settings 68
5. Installing a Cascade System 69
5.1 Connecting Water Supplies 69
5.2 Connecting the Communication Cables 71
Contents
Product Installation Information
Model
Date Purchased
Gas Type
Serial Number

3Important Safety Information
The following Safety Alert Symbols are used
in this manual. They are used to alert you
to potential personal injury hazards. Obey
all safety messages that follow this symbol to avoid
possible serious injury or death. This Safety Alert
Symbol precedes any safety message about risk of
personal injury. It may also be accompanied by one
of the following signal words.
If the information in these instructions is not
followed exactly, a fire or explosion may result,
causing property damage, personal injury or death.
DANGER
Indicates a hazardous situation that if not
avoided will result in death or serious injury.
WARNING
Indicates a hazardous situation that if not
avoided could result in death or serious injury.
CAUTION
Indicates a potentially hazardous situation that
if not avoided could result in minor or moderate
injury.
NOTICE
Indicates information considered important but
not hazard-related (such as property damage).
WARNING
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. Important Safety Information

4Important Safety Information
California law requires the following Prop 65
warning to be provided:
WARNING
Cancer and Reproductive Harm -
www.P65Warnings.ca.gov
WARNING
To prevent death, serious injury, or property
damage:
●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
To prevent death, serious injury, or property
damage:
●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.

5Important Safety 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 table 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
SAVE THESE
INSTRUCTIONS
DANGER
Indicates a hazardous
situation that if not
avoided will result in
severe injury or death.
WARNING
Indicates a hazardous
situation that if not
avoided could result
in death or serious
injury.
CAUTION
Indicates a potentially
hazardous situation
that if not avoided
could result in minor
or moderate injury.
NOTICE
Indicates information
considered important
but not hazard-
related (such as
property damage).
DANGER
HOT
BURN
Water temperatures over 125°F (52°C) can cause
severe burns instantly or death from scalds.
Children, disabled and elderly are at highest risk
of being scalded. Feel water with your elbow
before bathing or showering. Temperature
limiting valves are available, contact a licensed
plumber for more information.
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.
●Check local codes for maximum water
temperature setting allowed when used in
nursing homes, schools, day care centers and
other public applications.
●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 Included Items
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.
Installation Manual Quick Installation
Guide
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 Gas & High
Altitude Conversion Kit*
* Spare parts, High Altitude Conversion kit, and Propane
Gas & High Altitude Conversion Kit are attached to the
inside of the product case after the front cover has been
removed.
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 when the optional ComfortFlow recirculation is active. Energy consumption will increase when the
system is configured for circulation.

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.
bCombustion/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.
gMenu button Access to the Main
menu screen.
hBack button Access to the previous
screen.
iOK 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.
lPower 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 (VID)
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
Cold Water Inlet
Fitting
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 (VID)
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
Cold Water Inlet
Fitting
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 (VID)
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
Cold Water Inlet
Fitting
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.
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. (61mm)
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). If conversion to Propane Gas is
required, the included Propane Gas & High Altitude Conversion Kit must ALWAYS be used. Refer to the Propane
Gas & High Altitude Conversion Guide for more information.
Note The Propane Gas & High Altitude Conversion Kit is attached to the interior of the water heater cabinet.
You will need to remove the front cover to access the Propane Gas & High Altitude Conversion Kit.
If you need assistance, please call a licensed professional or Navien Technical Support at 1-800-519-
8794.
WARNING
To prevent death, serious injury or property damage:
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. Using a different
gas type will result in abnormal combustion and malfunction of the water heater.
●ONLY a licensed professional should connect the gas supply.
●ALWAYS leak test the appliance and the gas connections before operating the appliance.
●This water heater cannot be converted from natural gas to propane without a Navien Propane Gas & High
Altitude Conversion Kit. NEVER attempt a field conversion of this water heater without using the Navien
Propane Gas & High Altitude Conversion Kit. Doing so will result in dangerous operating conditions and
will void the warranty.
Navien Inc. is not liable for any property damage, personal injury or death resulting from improper
conversions.

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:
WARNING
●Review all of the installation information
in this manual before starting installation.
Consider all the requirements for venting,
piping, condensate removal, and wiring.
●Do not install this water heater in a
recreational vehicle, trailer, boat or other
moving vehicles as it will result in a Carbon
Monoxide Poisoning Hazard.
Note If the water heater is installed in
Massachusetts, see "Requirements for the
State of Massachusetts" on page 140.
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. See page
115 in the Appendix for more information on flushing
the heat exchanger.
**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 minimizes the length of the
intake and exhaust vent piping. 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 42.
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.
●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.
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.
Humidity and Contact with Water
When installing the water heater, avoid places with
excessive humidity. The water heater has electric
gas ignition components. Moisture can get inside
the water heater and damage the ignition system.
The water heater must be installed in a way to
ensure that the gas ignition system components are
protected from water (dripping, spraying, rain, etc.)
during operation and service.
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.
Note 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 38.
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
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.
●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 Altitude 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 61.
Natural gas units require the use of a Natural Gas
High Altitude Conversion Kit if installed at an
elevation of 5,400 ft (1,646 m) or higher.
WARNING
●ALWAYS read and follow the Natural Gas High
Altitude Conversion Guide when installing
the gas orifice included with the kit in order
to prevent death, serious injury or property
damage.
●The front cover will need to be removed from
the water heater to access the High Altitude
Conversion Kit.
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).
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 25.
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.

18 Installing the Water Heater
To mount the water heater to the wall:
1. Drill holes into studs and drill holes into the
drywall for plastic anchors. Insert anchors into
drywall. 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. Secure one screw to hold Wall Mounting
Bracket. Check that the bracket is level then
secure the remaining three screws.
3. With assistance from another person, lift the
water heater slightly above hooks on the
mounting bracket. Slowly lower until water
heater is resting on the mounting bracket
hooks. When mounted with the mounting
bracket, the back of the water heater will have a
5/8 inch (16 mm) clearance from the wall.
4. Install two screws (not included) through the
bracket at the bottom of the water heater to
secure it to 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.
●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.
NOTICE
●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.
●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.

19Installing the Water Heater
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.
Note The Gas Conversion Kit is located inside
the water heater cabinet. You will need
to remove the front cover to access the
Propane Gas & High Altitude Conversion
Kit.
3.3 Connecting the Gas Supply
WARNING
●E773 - Improper GasType DetectionWarning
This error code activates when the unit
detects a discrepancy between the gas type
set during installation and the gas type
connected to the unit. This function may not
detect all abnormal gas connections and that
the #1 DIP switch (Set of 8 Switches) setting
must be verified on the unit before use. The
unit may take some time to detect the gas
type discrepancy as it depends on the gas
flow rate and the exhaust outlet temperature.
The error code may activate with the correct
gas type and gas type setting due to varying
measuring tolerances in the unit.
If the error code persists when the DIP switch
setting matches the connected gas type,
contact Navien Technical Support.
●Using a different gas type will result in
abnormal combustion and malfunction of
the product.
To prevent death, serious injury or property
damage:
-ALWAYS check the Rating Plate located on
the side of the product matches the gas
type, gas pressure, water pressure, and
electrical supply available for the unit.
-CHECK the #1 DIP switch setting on the
Front panel matches the type of gas
supplied to the unit (OFF for Natural Gas
and ON for Propane Gas).
1 2
ON
Switch Function Setting
1Gas Type Natural Gas OFF
Propane Gas ON

20 Installing the Water Heater
To connect the gas supply:
1. Determine the gas type and pressure for the
water heater by referring to the rating plate.
2. Perform a pressure test on the main gas supply
line.
3. Purge the gas line of any debris.
4. Determine the proper size and type for the gas
line. Refer to the tables that follow.
5. Install certified full port valves on the gas supply
line and water heater.
6. Connect the gas supply line.
7. Test the supply line, all connection points, and
the water heater for gas leaks.
Union
Gas Shutoff
Valve
Gas
Supply
Gas Inlet Adapter
Bottom View
Pipe Size:
1
/
2
in.
to
3
/
4
in. (inner
diameter)
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