Navien NHW700 User manual

800.519.8794 www.navieninc.com
20 Goodyear lrvine, CA 92618
Installation Manual
NHW700 Non-Condensing Water Heaters
TANKLESS WATER HEATERS · BOILERS
Version: 1.0 (June, 2023)
Getting Service
If your water heater requires service:
●All repairs require pre-authorization by Technical Support.
●Request for your installer or any licensed professional to contact Technical Support at
1-800-519-8794 Option 2 once at the installation site.
●A short list of independent service providers in your area can be found on the website:
www.navieninc.com/installers.
●Contact a licensed professional for the affected system (for example, a plumber, gas fitter,
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

Model
NHW700-160AI/180AI/199AI
NHW700-160AE/180AE/199AE
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
NHW700 Non-Condensing Water Heaters
* Lead Fr
ee
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.
When applicable, the installation must conform with the Manufactured Home Construction and
Safety Standard,Title 24 CFR, Part 3280.
Do not install this water heater in a recreational vehicle, trailer, boat or other moving vehicles as it
will result in a Carbon Monoxide Poisoning Hazard.

2Contents
6. Appendixes 58
6.1 Covering the Clamps with Front Cover
Cap (for NSF 5 Use Only) 58
6.2 Technical Data 59
6.3 Wiring Diagram 61
6.4 Ladder Diagram 62
6.5 Component Assembly Diagrams and
Parts Lists 63
6.6 Installation Check list 75
6.7 Navien HAir Add-on Controller Kit
(Optional) 77
6.8 Requirements for the State of
Massachusetts 78
7. LIMITED WARRANTY NAVIEN, INC. 79
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 11
2.7 Rating Plate 13
3. Installing the Water Heater 14
3.1 Choosing an Installation Location 14
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 Venting the Water Heater (Indoor Models
Only) 34
3.6 Connecting the Power Supply 45
3.7 Setting the DIP Switches 46
4. Configuring the Remote Controller
System 49
4.1 Included Items 49
4.2 Connecting the Extension Cable 49
4.3 Attaching the Wall Mounting Bracket 49
4.4 Remote Controller 50
4.5 Multi Remote Controller System 51
4.6 Entering Lock Mode 53
4.7 Setting the Clock 53
4.8 Setting the Recirculation Timer 54
4.9 Starting Recirculation 55
4.10 Canceling all Timer Settings 55
5. Installing a Cascade System 56
5.1 Connecting Water Supplies 56
5.2 Connecting the Communication Cables 57
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).
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. 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 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,
User’s Information
Manual
Tapping Screws &
Anchors
Front Cover Caps
(for NSF use)
Remote Controller
(outdoor models only)
2.2 Accessories
The following optional accessories are available for
the water heater:
Remote Controller
Navien Plumb Easy
Valve Set with
Pressure Relief Valve
Ready-Link
Communication Cable
Navien HotButton
Kit / HAir Add-on
Controller Kit
Navi-Link
(Wi-Fi Control System)
Ready-Link Rack Recess Box
(Outdoor Models Only)
Recess Box
(Outdoor Models Only) Gas Conversion Kit
HotButton Push
Button HotButton Wall Plate
NaviCirc
(Recirculation Valve)
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 NHW700 Indoor NHW700 Outdoor
160AI 180AI 199AI 160AE 180AE 199AE
Heat
Capacity
(Input)
Natural Gas 10,700-160,000
BTU/H
10,700-180,000
BTU/H
10,700-199,900
BTU/H
10,700-160,000
BTU/H
10,700-180,000
BTU/H
10,700-199,900
BTU/H
Propane Gas
Uniform
Energy
Factor
UEF
(for NG&LP) 0.81 0.81 0.81 0.81 0.81 0.81
Flow Rate
(DHW)
45 °F
(25 °C) Temp
Rise
5.8 GPM
(22 L/m)
6.6 GPM
(25 L/m)
7.4 GPM
(28 L/m)
5.8 GPM
(22 L/m)
6.6 GPM
(25 L/m)
7.4 GPM
(28 L/m)
67 °F
(36 °C) Temp
Rise
4.0 GPM
(15 L/m)
4.5 GPM
(17 L/m)
5.0 GPM
(19 L/m)
4.0 GPM
(15 L/m)
4.5 GPM
(17 L/m)
5.0 GPM
(19 L/m)
Dimensions 17.3 in (W) x 26.5 in (H) x 10.3 in (D)
Weight (Gross) 60 lbs (27 kg) 65 lbs (29 kg) 65 lbs (29 kg) 60 lbs (27 kg) 65 lbs (29 kg) 65 lbs (29 kg)
Installation Type Indoor Wall-Hung Only Outdoor Wall-Hung Only
Venting Type Forced Draft Direct Vent (Indoor only)
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-13 in WC
Natural Gas Manifold
Pressure (Max.-Min.)
2.8 in W.C,
0.7 in W.C
2.3 in W.C,
0.7 in W.C
2.8 in W.C,
0.7 in W.C
3.2 in W.C,
0.8 in W.C
2.6 in W.C,
0.8 in W.C
3.2 in W.C,
0.8 in W.C
Propane Gas Manifold
Pressure (Max.-Min.)
5.8 in W.C,
1.3 in W.C
4.5 in W.C,
1.3 in W.C
5.4 in W.C,
1.3 in W.C
6.1 in W.C,
1.4 in W.C
4.9 in W.C,
1.3 in W.C
6.0 in W.C,
1.3 in W.C
Minimum Flow Rate 0.4 GPM (1.5 L/min), <0.01 GPM (0.04 L/min)
Connection
Sizes
Cold Water
Inlet
3/4
in NPT
Hot Water
Outlet
3/4
in NPT
Gas Inlet
3/4
in NPT
Power
Supply
Main Supply 120V AC, 60Hz
Normal 95 W 100 W 115 W 99 W 81 W 96 W
Maximum
Power
Consumption
350W (MAX 4 A)
Fuse
5.0 A
Materials
Fuse Cold Rolled Carbon Steel
Heat
Exchangers
Stainless Steel
Safety Devices Flame Rod, APS, Vent Installation Detector, Ignition Operation Detector,
Water Temperature High Limit Switch, Power Surge Fuse

8About the Water Heater
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.
Note The front panel of the outdoor model is placed inside the water heater. It is used only for installation
and maintenance.
a
b
c
d
e
f
g
h
i
j
k
af
h
ci
dj
ek
For indoor models For outdoor models
a
Error
g
Master Unit
A code will appear on the display Cascade operation
b
Hot Water Recirculation
h
Display
Recirculation Mode
c
Diagnostics button
i
Up button
For installers only Increases the temperature
d
Information button
j
Down button
Shows basic information Decreases the temperature
e
Reset button
k
Power button
Resets the water heater (When an error occurs) Turns the water heater on or off
f
Combustion
When the gas burner is on

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/Exhaust Duct
Condensate Drain
Stainless Steel Heat
Exchanger
Fan Motor
Gas Valve
Water
Adjustment Valve
NaviTech
TM
Burner
Front Panel
PCB
Gas Inlet Fitting
Water Inlet Filter
Ignition Transformer
APS (Air Pressure Sensor)
Recirculation Pump
Buffer Tank
DHW Supply Fitting
Recirculation Inlet
Adapter
[NHW700-160AI/180AI/199AI]
For Indoor Use Only

10 About the Water Heater
Stainless Steel Heat
Exchanger
Igniter&Flame Rod
NaviTech
TM
Burner
Fan Motor
Front Panel
Gas Valve
Water
Adjustment Valve
PCB
Gas Inlet Fitting
Water Inlet Filter
Ignition Transformer
Buffer Tank
APS (Air Pressure Sensor)
Recirculation Pump
DHW Supply Fitting
Recirculation Inlet
Adapter
[NHW700-160AE/180AE/199AE]
For Outdoor Use Only

11About the Water Heater
2.6 Dimensions
The following diagrams show the dimensions of the water heater and the table lists the supply connections.
28.2 in (716.5 mm) 26.5 in (675 mm)
Supply Connections
Description Diameter
AExhaust Gas Vent 3 in
BAir Intake 5 in
CCondensate Drain
5
/
8
in
DHot Water Outlet
3
/
4
in
EReturn Inlet
3
/
4
in
FGas Inlet
3
/
4
in
GCold Water Inlet
3
/
4
in
Overhead View
A B
C
4.6 in (117.7 mm)
8.6 in (220 mm)8.6 in (220 mm)
0.6 in (16 mm)
Supply Connections
DG FE
10.3 in (263.5 mm)
4.4 in (112.3 mm)4.4 in (112.3 mm) 3.9 in (99.8 mm)3.9 in (99.8 mm)
1.2 in
(30.8 mm)
2.7 in
(68.8
mm)
3 in
(76.3
mm)
5.9 in
(152.3
mm)
2.3 in
(60.2
mm)
17.3 in (440 mm)
5.5 in
(141.1 mm)
8.2 in (210.3 mm)
1.2 in (30.8 mm)
6.4 in (165 mm)
[NHW700-160AI/180AI/199AI]

12 About the Water Heater
28.2 in (716.5 mm)
7.9 in (201.5 mm)
1 in (26 mm)
26.5 in (675 mm)
Supply Connections
Description Diameter
AHot Water Outlet
3
/
4
in
BReturn Inlet
3
/
4
in
CGas Inlet
3
/
4
in
DCold Water Inlet
3
/
4
in
Overhead View
4.4 in (112 mm)
0.6 in (16 mm)
Supply Connections
ADC
B
10.3 in (263.5 mm)
4.4 in (112.3 mm)4.4 in (112.3 mm) 3.9 in (99.8 mm)3.9 in (99.8 mm)
1.2 in
(30.8 mm)
2.7 in
(68.8
mm)
3 in
(76.3
mm)
5.9 in
(152.3
mm)
2.3 in
(60.2
mm)
17.3 in (440 mm)
5.5 in
(141.1 mm)
8.2 in (210.3 mm)
1.2 in (30.8 mm)
6.4 in (165 mm)
[NHW700-160AE/180AE/199AE]

13About the Water Heater
2.7 Rating Plate
Water heaters come from the factory configured for use with Natural Gas (NG) or Propane Gas (LP). If a gas
conversion is required, the optional Gas Conversion Kit must ALWAYS be used. Refer to the Gas Conversion Guide
for more information.
Note The Gas Conversion Kit is available through a qualified installer or service agency. 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
Conversion Kit. NEVER attempt a field conversion of this water heater without using the Navien Propane
Gas 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.

14 Installing 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 the entire installation information in this
manual before starting installation. Consider all
the requirements for venting, piping, and wiring.
Note If the water heater is installed in
Massachusetts, see “6.8 Requirements
for the State of Massachusetts“ on page
78.
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
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 Water
Heater Flush Procedures.
**Check local codes for any restrictions on use of water
softeners
Water Heater Flushing Procedures
NOTICE
Flushing the Heat Exchanger can be a difficult
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“Dimensions”on page 11 for details about
part locations.
Before flushing the Heat Exchanger, gather the
following items:
●A bucket that is 5 gallons or larger
●Cleaning solution diluted with water
●3 hoses
●A water circulation pump
3. Installing the Water Heater

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

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 “3.5 Venting the Water Heater (Indoor Models
Only)” on page34.
WARNING
Improper venting of the water heater can result
in excessive levels of carbon monoxide, which
can lead to severe personal injury or death. This
water heater must be vented in accordance
with the “Venting of Equipment“ section of
the latest edition of the ANSI Z223.1/NFPA
54 Natural Fuel Gas Code in the USA, as well
as all applicable local building codes and
regulations. Follow all instructions and guidelines
when venting the water heater. Venting should be
performed only by a qualified service agency.
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.
●Avoid installing the water heater in bedrooms or
any other occupied rooms that are normally kept
closed or that are not adequately ventilated.
●Install a carbon monoxide detector in
dwelling areas nearby the appliance. Refer
to manufacturer’s instructions as well as the
Consumer Product Safety Commission (CPSC)
and Environmental Protection Agency (EPA)
recommendations for proper use of carbon
monoxide alarms.
Adequate Drainage
This non-condensing water heater may produce
condensate within the vent system due to the
condition of the installation. Condensate can be
drained through the condensate collector. 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.
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.
Note Navien will not be liable for any
damages caused by water leaks.

17Installing the Water Heater
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,
perchlorethylene, chlorine, 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 water heater may be installed at elevations up
to 10,100 ft (3,078 m) for use with Natural Gas and
Propane. Refer to“3.7.2 Setting the Front Panel DIP
Switches” on page47 for the appropriate altitude
setting.
Note Do NOT install this water heater at
elevations above 10,100 ft (3,078 m).
Coastal Installations
For installations in sea or marine environments, the
salty air can cause corrosion to the water heater.
The water 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 freezing temperature of 32˚F (0˚C)
and below 125˚F (52˚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:
For indoor installation
Clearance
from: to Combustibles to Non-
Combustibles
Top 6 in (152 mm)
minimum
2 in (51 mm)
minimum
Back 0 in (0 mm)
minimum
0 in (0 mm)
minimum
Front 6 in (152 mm)
minimum
6 in (152 mm)
minimum
Sides 2 in (51 mm)
minimum
1/2 in (13 mm)
minimum
Ground/
Bottom
12 in (305 mm)
minimum
12 in (305 mm)
minimum
Vent 0 in (0 mm)
minimum
0 in (0 mm)
minimum
For outdoor installation
Clearance
from: to Combustibles to Non-
Combustibles
Top 12 in (305 mm)
minimum
2 in (51 mm)
minimum
Back 0 in (0 mm)
minimum
0 in (0 mm)
minimum
Front
(panel)
24 in (610 mm)
minimum
0 in (0 mm)
minimum
Front
(exhaust)
24 in (610 mm)
minimum
24 in (610 mm)
minimum
Sides 6 in (152 mm)
minimum
1/8 in (3.2 mm)
minimum
Ground/
Bottom
12 in (305 mm)
minimum
2 in (51 mm)
minimum

18 Installing the Water Heater
To mount the water heater to the wall:
1. Ensure that the strength of the wall is sufficient
to support the weight of the water heater.
2. Securely attach the water heater to the wall by
affixing the brackets at the top and bottom of
the water heater using the provided screws.
3. Ensure that the water heater is level using a
leveling tool.
4. The top and bottom mounting brackets on the
water heater are adjustable to provide flexibility
in aligning the vent with the unit vent collar.
3.2 Mounting the Water Heater to
the Wall
Navien water heaters come with two upper and
lower mounting brackets that are pre-drilled at 16
in 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
●If the water heater is not properly and
securely attached to the wall, it could become
dislodged causing the exhaust vent pipe to
separate. This can result in carbon monoxide
emissions which could cause severe personal
injury or death.
●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 upright in the 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
installed weight of the water heater, including
water content of 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
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 pipes 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 pipes with hangers. Do
not allow the pipes 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 of 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 installed by a
qualified service agency.
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 setting must be verified on
the Front panel 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).
12 3 4 5 6 7 8 9 10
ON ON
ON OFF
1
2 3 4 5 6 7 8 9 10
ON
ON OFF
[NHW700 Indoor Models] [NHW700 Outdoor Models]
Switch Function Setting
1Gas Type
Natural Gas 1: OFF
Propane Gas 1: ON