Navien NPE-180A User manual

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,
ANSIZ223.1/NFPA 54 and/or CSA B149.1, Natural Gas and Propane Installation Code.
When applicable, the installation must conform with the Manufactured Home Construction and Safety
Standard, Title 24 CFR, Part 3280 and/or CAN/CSA Z240 MH Series, Mobile Homes.
* 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.
Installation Manual
NPE Condensing Water Heaters
Model
NPE-180A
NPE-210A
NPE-240A
NPE-150S
NPE-180S
NPE-210S
NPE-240S

2 Contents
1. Safety Information 3
2. About the Water Heater
5
2.1 Items Included 5
2.2 Accessories 5
2.3 Specifications 6
2.4 The Front Panel 7
2.5 Components 8
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 15
3.3 Connecting the Gas Supply 16
3.4 Connecting the Water Supply 20
3.5 Connecting the Condensate Drain 26
3.6 Venting the Water Heater 28
3.7 Connecting the Power Supply 35
3.8 Setting the DIP Switches 35
4. Installing a Cascading System 37
4.1 Connecting Water Supplies 37
4.2 Connecting the Communication Cables 38
5. Appendixes 40
5.1 Gas Conversion 40
5.2 Technical Data 46
5.3 Wiring Diagram 49
5.4 Ladder Diagram 51
5.5 Component Assembly Diagrams and Parts Lists 53
5.6 Installation Check list 65
5.7 Navien ComfortAir+ Add-on Controller Kit (Optional) 67
5.8 Navien On-Demand Control Kit (Optional) 68
5.9 Requirements for the State of Massachusetts 69
Contents

Safety Information 3
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

4 Safety Information
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.
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.
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 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.

About the Water Heater 5
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.
Installation &
Operation Manual Quick Installation Manual
Wall Mounting Bracket Tapping Screws & Anchors
2 in Vent Termination Caps 2 in Wall Flanges
Conversion Kit Spare Parts
2.2 Accessories
The following optional accessories are available for the water
heater:
Remote Controller Plumb Easy Valve Set
Pressure Relief Valve Condensate Neutralizer
Ready-Link
Communication Cable Outdoor Vent Kit
3 in Vent Termination Caps 3 in Wall Flanges
External Pump Connector
(<150 W, 1.5 A)
Navien On-Demand /
Comfort Air+ Add-on
Controller Kit
2. About the Water Heater

6 About 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-150S NPE-180A NPE-180S NPE-210A NPE-210S NPE-240A NPE-240S
Heat
Capacity
(Input)
Natural Gas 18,000-
120,000
BTU/H
15,000-150,000 BTU/H 19,900-180,000 BTU/H 19,900-199,900 BTU/H
Propane Gas 15,000-150,000 BTU/H 19,900-180,000 BTU/H 19,900-199,900 BTU/H
Efficiency
Ratings
UEF
(for NG & LP) 0.96 0.96 0.97 0.96 0.97 0.96 0.97
EF (Canada)
(for NG & LP) 0.97 0.97 0.99 0.97 0.99 0.97 0.99
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 3.2 GPM
(12 L/m)
4.3 GPM
(16 L/m)
4.2 GPM
(16 L/m)
5.0 GPM
(19 L/m)
5.2 GPM
(20 L/m)
5.6 GPM
(21 L/m)
5.7 GPM
(22 L/m)
Dimensions 17.3 in (W) x 27.4 in (H) x 13.2 in (D)
Weight 62 lbs
(28 kg)
75 lbs
(34 kg)
67 lbs
(30 kg)
82 lbs
(37 kg)
75 lbs
(34 kg)
82 lbs
(37 kg)
75 lbs
(34 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-13 in WC
Natural Gas Manifold Pressure
(min-max)
-0.04 in WC -
-0.40 in WC -0.04 in WC - -0.84 in WC -0.05 in WC - -0.36 in WC -0.05 in WC - -0.58 in WC
Propane Gas Manifold Pressure
(min-max)
-0.05 in WC -
-0.42 in WC -0.05 in WC - -0.50 in WC -0.10 in WC - -0.66 in WC -0.10 in WC - -0.78 in WC
Minimum Flow Rate 0 GPM (0 L/m) for“A” models / 0.5 GPM (1.9 L/m) for“S”models
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 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, Polypropylene
2 in or 3 in Special Gas Vent Type BH (Class II, A/B/C)
Intake 2 in or 3 in PVC, CPVC, 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

About the Water Heater 7
a
b
c
d
e
f
g
h
i
j
k
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
Error
g
Master Unit
A code will appear on the display Cascade operation
b
Hot Water Recirculation
h
Display
Recirculation Mode
c
Diagnostics button
i
Up button
For installers only Increases the temperature
d
Information button
j
Down button
Shows basic information Decreases the temperature
e
Reset button
k
Power button
Resets the water heater (When an error occurs) Turns the water heater on or off
f
Combusting
When the gas burner is on

8 About 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
Exhaust Duct
Exhaust Limit Temperature Sensor
Exhaust Body
Ignition Transformer
Burner
Primary Heat Exchanger
Secondary Heat Exchanger
Flow Sensor
Condensate Trap
Front Panel
PCB Box
Water Adjustment Valve
Water Inlet Filter
Condensate Drain Fitting
Condensate Drain Lid
Fan Motor
Dual Venturi
Gas Pipe
APS (Air Pressure Sensor)
Buffer Tank
Circulation Pump
Gas Valve
Gas Inlet Fitting
DHW Supply Fitting
2-Way Valve
Recirculation Inlet Fitting
[NPE-180A/ 210A/ 240A]

About the Water Heater 9
Intake Air Duct
Exhaust Duct
Exhaust Limit Temperature Sensor
Exhaust Body
Ignition Transformer
Burner
Primary Heat Exchanger
Secondary Heat Exchanger
Flow Sensor
Condensate Trap
Front Panel
PCB Box
Mixing Valve
Water Inlet Filter
Condensate Drain Fitting
Condensate Drain Lid
Fan Motor
Single Venturi
Gas Pipe
APS (Air Pressure Sensor)
Gas Valve
Freeze Protection Switch
Gas Inlet Fitting
Water Adjustment Valve
DHW Supply Fitting
[NPE-150S]

10 About the Water Heater
Intake Air Duct
Exhaust Duct
Exhaust Limit Temperature Sensor
Exhaust Body
Ignition Transformer
Burner
Primary Heat Exchanger
Secondary Heat Exchanger
Flow Sensor
Condensate Trap
Front Panel
PCB Box
Mixing Valve
Water Inlet Filter
Condensate Drain Fitting
Condensate Drain Lid
Fan Motor
Dual Venturi
Gas Pipe
APS (Air Pressure Sensor)
Gas Valve
Freeze Protection Switch
Gas Inlet Fitting
Water Adjustment Valve
DHW Supply Fitting
[NPE-180S/ 210S/ 240S]

About the Water Heater 11
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
A Air Intake 2 in
B Exhaust Gas Vent 2 in
C Hot Water Outlet
3
/
4
in
D Recirculation Inlet
3
/
4
in
E Cold Water Inlet
3
/
4
in
F Gas Inlet
3
/
4
in
G Condensate Outlet
1
/
2
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)
CF D G E
[NPE-180A/ 210A/ 240A]

12 About the Water Heater
27.4 in (695 mm)
28.8 in (731 mm)
Supply Connections
Description Diameter
A Air Intake 2 in
B Exhaust Gas Vent 2 in
C Hot Water Outlet
3
/
4
in
D Cold Water Inlet
3
/
4
in
E Gas Inlet
3
/
4
in
F Condensate Outlet
1
/
2
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)
CF DE
2.3 in (60 mm) 11.3 in (289 mm)
17.3 in (440 mm)
2.4 in (61 mm)
[NPE-150S/ 180S/ 210S/ 240S]

About the Water Heater 13
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 gas conversion kit must be used. Refer to “5.1 Gas Conversion” for details.
Rating Plate, *Plaque Signalétique
Direct Vent Automatic Instantaneous Water Heater *Chauffe-eau instantané automatique à évent direct
For Indoor, Outdoor or Manufactured Home (Mobile Home) Installation *Pour installation dans une maison préfabriquée (mobile)
Navien, Inc.
20 Goodyear, Irvine, CA 92618
Tel: [phone]
Orifices necessary for LP conversion are provided. *Les injectures nécessaires à la conversion au GPL sont fournis.
Failure to use the correct gas can cause problems which can result in death, serious injury or property damage. *Le fait de ne pas
utiliser le bon gaz peut causer des problèmes qui peuvent mener à la mort, causer des blessures graves ou endommager la propriété.
Consult your installation manual for more information. *Consultez votre manuel d’installation pour plus d’information.
Suitable for combination water (potable) heating and space heating and not suitable for space heating applications only.
*Convient au chauffage combiné de l’eau (potable) et des locaux, mais non au chauffage des locaux seulement.
This appliance is certified for use at altitudes up to 4,500 ft (1,370 m) in accordance to the latest CAN/CGA 2.17-High Altitude Installation
procedures at normal manifold pressure. For installation instructions at altitudes higher than 4,500 ft, please contact Navien. *Cet appareil
est certifié pour une utilisation à des altitudes de 0 à 4,500 pieds (1,370 m) conformément aux toutes les procédures d’installation à haute
altitude CAN/CGA 2.17 à une pression normale. Pour les installations à élévations en haut de 4,500 pieds, appeler le bureau de Navien.
This appliance must be installed in accordance with local codes, or in the absence of local codes, the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 or the CSA B149.1, Natural Gas and Propane Installation Code. *Cet appareil doit être installé selon les règlements
locaux, ou en l’absence de tels règlements, selon le National Fuel Gas Code, ANSI Z223.1/NFPA 54, ou les, Code d'installation du gaz
natural et du propane, CSA-B149.1.
Model No., *Numéro de modèle
NPE-210A
Max. Input Rating, *Entrée GPL max.
180,000 Btu/h
Recovery Rating, *Calibre de recouvrement
Max. Inlet Gas Pressure, *Pression max. de gaz d’entrée
Min. Inlet Gas Pressure, *Pression min. de gaz d’entrée
Manifold Pressure, *Pression d’admission
Electrical Rating, *Régime nominal électrique
Max. Water Pressure, *Pression d’eau max.
Type of Gas, *Type de gaz
NG
Min. Input Rating, *Débit calorifique max.
19,900 Btu/h
265 Gallons/Hour, *gallons/heures
10.5 Inches W.C. *pouces W.C.
3.5 Inches W.C. *pouces W.C.
-0.36 Inches W.C. *pouces W.C.
AC *c.a. 120 Volts 60Hz, less than 2 amperes, *Utilise moins de 2A
150 psi *lb/po2 ANSI Z21.10.3 · CSA 4.3-2011
FOR YOUR SAFETY *POUR VOTRE SÉCURITÉ
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other gas appliances. *Ne rangez
pas et n'utilisez pas d'essence ou d'autres liquides ou vapeurs inflammables près de cet appareil ou de tout autre appareil électroménager.
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.

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:
About Water Quality
Proper maintenance of the water heater is required to ensure
that your water meets EPA quality standards. 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
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
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 20.
3. Installing the Water Heater

Installing the Water Heater 15
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. Avoid installation on common walls as the unit will
make some operational noises while it is running.
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.
CAUTION
Do not mount the water heater to dry wall that has not been
reinforced.
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 (20 mm)
minimum
0.5 in (20 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.
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 water heater may be installed at elevations up to 10,100 ft
(3,078 m) for use with Natural Gas and 4,500 ft (1,370 m) for
use with Propane. Refer to “3.8.2 Setting the Front Panel DIP
Switches” on page35 for the appropriate altitude setting.

16 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 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)
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.
The appliance and its gas connection must be leak tested
before placing the appliance in operation.
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.
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

Installing the Water Heater 17
Note
Tighten the water heater connection valves with
care to avoid damage.
The gas connection fitting on all water heaters is
3
/
4
in.

1
/
2
in rigid pipe can be used; refer to the sizing
tables on the proceeding pages for limitations.
Avoid using
1
/
2
in corrugated connectors or tubing
as noise may occur.
Corrugated Connector
When using flexible gas lines, ensure that the
pipe’s inner diameter and connector is sufficient
to supply the required BTUs. Also, ensure that the
flexible line has no crimps or tight bends in it, as
this will restrict gas flow.
When using rigid pipe, Navien recommends the
installation of a union on the gas supply line
close to the water heater, to facilitate any future
maintenance or service.
CAUTION
Prior to using an excess flow valve (EFV) in the gas line, check
the manufacturer's minimum and maximum flow capacity
rating. An improperly sized EFV wil not allow for a full flow of
gas to the water heater and may cause improper operation.
CLOSE: 195
MAX OPER: 135
BYPASS: 5
KBTU /HR
CLOSE: 195
MAX OPER: 135
BYPASS: 5
KBTU
/HR
Excess Flow Valve
Typical LP Gas piping examples:
2 Stage System with Multiple Regulators (Recommended)
Gas Regulators
(2 Stage)
Full size
Gas Pipe
Gas Tank
High Pressure
Regulator
Low Pressure
Regulator
Single Regulator System
Gas Regulator
12 in W.C.
Gas Tank Full size
Gas Pipe
Full size
Gas Pipe
Pipe

18 Installing the Water Heater
3.3.1 Gas Pipe Sizing Tables (Referenced from 2012 National Fuel Gas Code)
These tables are for reference only. Please consult the gas pipe manufacturer for actual pipe capacities.
Maximum Natural Gas Delivery Capacity
in Cubic Feet (ft
3
) per Hour (0.60 Specific Gravity; 0.5 in WC Pressure Drop). Contact your gas supplier for BTU/ft
3
ratings. Use 1,000 BTU/ft
3
for
simplified calculations. This table is recommended for supply pressures less than 6 in WC.
Pipe Size
Length (including fittings)
10 ft
(3 m)
20 ft
(6 m)
30 ft
(9 m)
40 ft
(12 m)
50 ft
(15 m)
60 ft
(18 m)
70 ft
(21 m)
80 ft
(24 m)
90 ft
(27 m)
100 ft
(30 m)
125 ft
(38 m)
3
/
4
in 360 247 199 170 151 137 126 117 110 104 92
1 in 678 466 374 320 284 257 237 220 207 195 173
1
1
/
4
in 1,390 957 768 657 583 528 486 452 424 400 355
1
1
/
2
in 2,090 1,430 1,150 985 873 791 728 677 635 600 532
2 in 4,020 2,760 2,220 1,900 1,680 1,520 1,400 1,300 1,220 1,160 1,020
2
1
/
2
in 6,400 4,400 3,530 3,020 2,680 2,430 2,230 2,080 1,950 1,840 1,630
3 in 11,300 7,780 6,250 5,350 4,740 4,290 3,950 3,670 3,450 3,260 2,890
4 in 23,100 15,900 12,700 10,900 9,660 8,760 8,050 7,490 7,030 6,640 5,890
in Cubic Feet (ft
3
) per Hour (0.60 Specific Gravity; 3.0 in WC Pressure Drop). Contact your gas supplier for BTU/ft
3
ratings. Use 1,000 BTU/ft
3
for
simplified calculations. This table is recommended for supply pressures of 6 in WC or greater.
Pipe Size
Length (including fittings)
10 ft
(3 m)
20 ft
(6 m)
30 ft
(9 m)
40 ft
(12 m)
50 ft
(15 m)
60 ft
(18 m)
70 ft
(21 m)
80 ft
(24 m)
90 ft
(27 m)
100 ft
(30 m)
125 ft
(38 m)
1
/
2
in 454 312 250 214 190 172 158 147 138 131 116
3
/
4
in 949 652 524 448 397 360 331 308 289 273 242
1 in 1,787 1,228 986 844 748 678 624 580 544 514 456
1
1
/
4
in 3,669 2,522 2,025 1,733 1,536 1,392 1,280 1,191 1,118 1,056 936
1
1
/
2
in 5,497 3,778 3,034 2,597 2,302 2,085 1,919 1,785 1,675 1,582 1,402
2 in 10,588 7,277 5,844 5,001 4,433 4,016 3,695 3,437 3,225 3,046 2,700
2
1
/
2
in 16,875 11,598 9,314 7,971 7,065 6,401 5,889 5,479 5,140 4,856 4,303
3 in 29,832 20,503 16,465 14,092 12,489 11,316 10,411 9,685 9,087 8,584 7,608
4 in 43,678 30,020 24,107 20,632 18,286 16,569 15,243 14,181 13,305 12,568 11,139

Installing the Water Heater 19
Maximum Liquefied Propane Delivery Capacity
in Thousands of BTU/H (0.5 in WC Pressure Drop)
Pipe Size
Length (including fittings)
10 ft
(3 m)
20 ft
(6 m)
30 ft
(9 m)
40 ft
(12 m)
50 ft
(15 m)
60 ft
(18 m)
80 ft
(24 m)
100 ft
(30 m)
125 ft
(38 m)
150 ft
(45 m)
175 ft
(53 m)
200 ft
(60 m)
250 ft
(76 m)
1
/
2
in 291 200 160 137 122 110 101 94 89 84 74 67 62
3
/
4
in 608 418 336 287 255 231 212 197 185 175 155 140 129
1 in 1,150 787 632 541 480 434 400 372 349 330 292 265 243
1
1
/
4
in 2,350 1,620 1,300 1,110 985 892 821 763 716 677 600 543 500
1
1
/
2
in 3,520 2,420 1,940 1,660 1,480 1,340 1,230 1,140 1,070 1,010 899 814 749
2 in 6,790 4,660 3,750 3,210 2,840 2,570 2,370 2,200 2,070 1,950 1,730 1,570 1,440
3.3.2 Measuring the Inlet Gas Pressure
WARNING
The water heater cannot function properly without sufficient inlet gas pressure. Measuring the inlet gas pressure should be performed by
a licensed professional only.
The inlet gas pressure must be maintained between 3.5 in and 10.5 in WC for natural gas and between 8.0 in and 13 in WC for liquefied
propane.
The appliance and its individual shutoff valve must be disconnected from the gas supply piping system during any pressure testing of
that system at test pressures in excess of
1
/
2
psi (3.5 kPa). The appliance must be isolated from the gas supply piping system by closing its
individual manual shutoff valve during any pressure testing of the gas supply piping system at test pressures equal to or less than
1
/
2
psi (3.5
kPa).
To measure the inlet gas pressure:
1. Shut off the manual gas valve on the gas supply line.
Gas Valve
Opened Closed

20 Installing the Water Heater
8. When the water heater reaches its maximum firing rate, check
the inlet gas pressure reading on the manometer. The gas
pressure must fall within the ranges specified on page 19.
3.4 Connecting the Water Supply
The water fittings on the water heater are
3
/
4
in. If the installation
site only has
1
/
2
in plumbing throughout, it is not necessary to
upsize the water lines to
3
/
4
in, if you are installing a single water
heater. When installing multiple water heaters, the number of
water heaters and pipe sizing required will depend on the total
hot water demand. For information about pipe sizing for multiple
water heaters, refer to "4.1.1 Piping Sizes and Considerations" on
page 38.
When connecting the water supply, follow these guidelines:
Do not remove the factory installed recirculation inlet cap unless
a return line is connected to this fitting. Water leakage will occur
if this cap is loose or missing ("A" model only).
Use only pipes, fittings, valves, and other components, such as
solder, that are approved for use in potable water systems.
Tighten the water heater connection valves with care to avoid
damage.
We recommend using unions and manual shut-off valves on the
cold water inlet, DHW outlet, and recirculation water inlet.
Strive to make the hot water piping system as short as possible,
to deliver hot water to the fixtures more quickly.
To conserve water and energy, insulate all water piping—
especially the hot and recirculation water lines. Never cover the
drain or pressure relief valve. If the water heater is installed in
a closed water supply system, such as one having a backflow
preventer in the cold water supply line, means shall be provided
to control thermal expansion. Contact the water supplier or local
plumbing inspector for information about how to control this
situation.
After installing the water heater, clean the inlet water filter that
is located inside the cold water inlet, and then test the water
heater for proper flow and inspect for leaks. Instruct the water
heater owner that the filter must be cleaned periodically to
maintain proper water flow.
2. Open a hot water faucet. The water heater should turn on and
the gas in the gas supply line will be purged.
3. Leave the faucet on until the water heater shuts down due to a
lack of gas supply, and then turn off the hot water faucet.
4. Remove the water heater front cover by loosening the
4Phillips head screws securing it to the case.
5. Loosen the screw indicated in the figure below and connect a
manometer to the pressure port. Reset the manometer to zero
before use.
Digital pressure
manometer
6. Re-open the manual gas valve and check for leaks.
7. Open multiple fixtures that have high flow rates, such as
bathtub and shower faucets, to ramp the water heater up to its
maximum firing rate.