A.O. Smith THR-160 Product information sheet

Installaon Instrucons and
Use & Care Guide
Keep this manual with the heater for future reference whenever maintenance, adjustment or service is required.
Retain your original receipt as proof of purchase.
Read this manual and the labels on the water heater before you install,
operate, or service it. If you have difficulty following the direcons, or
aren’t sure you can safely and properly do any of this work yourself:
• Call our Technical Assistance Hotline which is listed on your warranty. We can
help you with installaon, operaons, troubleshoong, or maintenance. Before
you call, write down the model and serial number from the water heater’s rang
plate.
• Incorrect installaon, operaon, or service can damage the water heater, your
house and other property, and present risks including fire, scalding, electric
shock, and explosion, causing serious injury or death.
Residenal Gas
Tankless Water Heater
Residenal On-Demand Gas Tankless Water Heater
(X3™ TECHNOLOGY available on some models)
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 instrucons.
•If you cannot reach your gas supplier, call the fire de-
partment.
Installaon and service must be performed by a qualified
installer, service agency or the gas supplier.
WARNING: If the informaon in these instrucons
is not followed exactly, a fire or explosion may
result causing property damage, personal injury or
death.
MODEL:
THR-160, THR-180, THR-199
LOW LEAD
C
O
NTENT
100374994_2000628591
December 2023

2 • Residenal Tankless Gas Water Heater Use and Care Guide
TABLE OF CONTENT
WATER HEATER BASICS ....................................................................................4
COMPONENT VIEW (X3®Model Shown) ..................................................................................................4
TYPICAL INSTALLATION (X3®Model Shown)..............................................................................................5
DIMENSIONS .............................................................................................................................................6
SUPPLY CONNECTIONS ..............................................................................................................................7
SPECIFICATIONS.........................................................................................................................................8
IMPORTANT SAFETY INFORMATION.................................................................9
RISKS DURING INSTALLATION AND MAINTENANCE ................................................................................10
RISKS DURING OPERATION......................................................................................................................10
GETTING STARTED .........................................................................................12
Read Before InstallaƟon..........................................................................................................................12
Included Items.........................................................................................................................................14
Available Accessories ..............................................................................................................................15
INSTALLATION................................................................................................17
InstallaƟon Environment.........................................................................................................................17
Unit Clearances .......................................................................................................................................17
MounƟng the Water Heater ...................................................................................................................17
CombusƟon and VenƟng InstallaƟon ......................................................................................................18
VenƟng....................................................................................................................................................21
Installing the Vent Pipe. ..........................................................................................................................23
Exhaust Vent for Indoor InstallaƟon........................................................................................................23
Clearances for Sidewall TerminaƟons .....................................................................................................28
Clearances for RooŌop TerminaƟons ......................................................................................................29
Exhaust VenƟng for Outdoor InstallaƟon................................................................................................30
Outdoor Available Accessories ................................................................................................................30
Gas Conversion InstrucƟons ....................................................................................................................33
Water ConnecƟons..................................................................................................................................33
RecirculaƟon ...........................................................................................................................................34
CombinaƟon Potable Water HeaƟng ......................................................................................................36

Residenal Gas Tankless Water Heater Use and Care Guide • 3
TABLE OF CONTENTS
Dual Purpose Water HeaƟng for the State of MassachuseƩs.................................................................37
X3®Technology .......................................................................................................................................38
Pressure Relief Valve ...............................................................................................................................38
Electrical ConnecƟons .............................................................................................................................40
Cascade System.......................................................................................................................................41
OPERATION ...................................................................................................43
FOR YOUR SAFETY, READ BEFORE OPERATING........................................................................................ 43
Temperature Adjustment ........................................................................................................................46
Unit Conversion Mode.............................................................................................................................47
ConfiguraƟon Mode (A Mode) ................................................................................................................48
ConfiguraƟon Mode (C Mode) ................................................................................................................48
Seƫng the Clock .....................................................................................................................................49
Seƫng RecirculaƟon Modes....................................................................................................................50
Seƫng the Pump Timers .........................................................................................................................52
Pump Timer AcƟvaƟon............................................................................................................................53
MAINTENANCE..............................................................................................54
Regular Maintenance..............................................................................................................................54
Unit Draining & Power Outage
(Freeze ProtecƟon) .................................................................................................................................55
Condensate Drain....................................................................................................................................55
TROUBLESHOOTING .....................................................................................56
General TroubleshooƟng.........................................................................................................................56
Error Codes..............................................................................................................................................57
Fault Analysis of Error Codes...................................................................................................................57
COMPONENT LIST..........................................................................................63
FLOW RATE....................................................................................................70
NOTES ...........................................................................................................71

4 • Residenal Gas Tankless Water Heater Use and Care Guide
WATER HEATER BASICS
X3 Cartridge
Control Display
Printed Circuit Board
Gas Valve
Fan Motor Assembly
Exhaust Port
Inlet Port
Igniter Rod
Flame Sensor
Gas Valve
Venturi Assembly
Flow Sensor Control
Valve Assembly
Igniter
Condensate Trap
Air Pressure Switch
Bypass Valve
Burner Assembly
Pressure Relief Valve
(M Model: Field Supplied)
Pump
Bypass Cartridge
(M Model: Alternative Configuration)
Heat Exchanger
COMPONENT VIEW (X3® Model Shown)
X3® Technology (X3® Model):
This water heater is equipped with X3®Scale Prevenon Technology to inhibit scale formaon within the heat exchanger
tubing of this unit. Part of the X3®Technology’s an-scale protecon comes from the special X3®Cartridge media. The
X3®Cartridge must be installed into the manifold located on the underside of the heater cabinet prior to operaon of
the unit. X3®Scale Prevenon Technology reduces the formaon of scale in the heat exchanger, extending the operang
life of the unit in typical potable water installaons. Specific water condions may impact the efficiency of X3®, such
as excessive iron or manganese levels. Refer to the guidelines below and consult a water quality expert to determine if
your water is within acceptable X3®and EPA guidelines. NOTE: Pressure Relief Valve supplied in the box with this model.
Bypass Cartridge (M Model):
The ByPass cartridge will come preinstalled from the factory. Please verify the three screws securing the ByPass
cartridge are ghtened, See Figure 34. NOTE: Pressure Relief Valve will need to be field supplied with this model.

Residenal Gas Tankless Water Heater Use and Care Guide • 5
Expansion
Tank
Outlet Venting
Inlet Air
Pressure Relief Valve
(Drain Line not
shown for clarity)
Water
Shutoff Valve Water
Shutoff Valve
HWS CWS
Drip Leg
Gas Line
Gas
Shutoff Valve
NOTE: Condensate Drain not shown for clarity.
WATER HEATER BASICS
TYPICAL INSTALLATION (X3® Model Shown)

6 • Residenal Gas Tankless Water Heater Use and Care Guide
WATER HEATER BASICS
DIMENSIONS
16.54 in
42.00 cm
5.09 in
12.92 cm
6.70 in
17.00 cm
4.00 in
10.16 cm
C
L
12.28 in
31.20 cm
33.80 in
85.88 cm
3.73 in
9.47 cm
Wall
Water heater wall
mount contact point.
16.12 in
40.96 cm
8.31in
21.12 cm
5.08 in
12.90 cm
3.22 in
8.22 cm
6.58 in
16.72 cm
Wall Studs
Dry Wall
41.78 in
106.13 cm
26.70 in
67.82 cm

Residenal Gas Tankless Water Heater Use and Care Guide • 7
WATER HEATER BASICS
Table 1: Supply Connecons
Item DESCRIPTION MEASUREMENT CONNECTION SIZE
1 HOT OUTLET 9.00 in/23 cm 3/4” MNPT
2GAS INLET 6.90 in/17.52 cm 1/2” MNPT
3 CONDENSATE 3.20 in/8.07 cm 1/2” MNPT
4 COLD INLET 4.80 in/12.20 cm 3/4” MNPT
WALL
12
34
SUPPLY CONNECTIONS

8 • Residenal Gas Tankless Water Heater Use and Care Guide
X3® Models: Comes with the X3®Scale Prevenon Technology cartridge and pressure relief valve.
M Models: Come with the bypass cartridge installed.
All other specificaons are the same.
Table 2: - Specificaons
Model THR-160 THR-180 THR-199
Natural Gas/Propane Input
(Minimum Operating Range) BTU/h 9,000
Natural Gas/Propane Input
(Maximum Operating Range) BTU/h 160,000 180,000 199,000
Gas Connection 1/2" NPT
Water Connections 3/4" NPT
Water Pressure* psi (MPa) 15 - 150 (0.1 - 1)
Water Flow Rate gpm (Lpm) 0.26 - 10.5 (1.0 - 39.7), Activation min: 0.4 (1.5)
Natural gas
Inlet Pressure " W.C. (kPa) Min 3.5 (0.87) Max. 10.5 (2.62)
Propane
Inlet Pressure " W.C. (kPa) Min 8.0 (1.99) Max. 13.0 (3.24)
Weight lbs. (kg) 104 (47.2)
Dimensions
(including X3®)
inch W 16.54 x H 41.78 x D 16.12
cm W 42.00 x H 106.13 x D 40.96
Ignition Electronic Ignition
Electric
Supply 120V, 50Hz/60Hz, <5A
Water Heater Category** Category IV
Maximum Pipe length
(Hot Water supply line and Dedicated
Return line)
Pipe
Diameter
3/4" 500 ft (152.4 m)
1/2" 200 ft (61 m)
*40 psi or above is recommended for maximum flow.
**Water Heater Category - Does not apply to Outdoor or Direct Vent Installations.
Category IV - a water heater that operates with a positive vent static pressure and with a vent gas temperature that may cause
excessive condensate production in the vent.
NOTE:
• Check the rating plate to ensure that this product matches your specifications.
• The manufacturer reserves the right to discontinue, or change at any time, specifications or designs without
notice and without incurring obligation.
WATER HEATER BASICS
SPECIFICATIONS

Residenal Gas Tankless Water Heater Use and Care Guide • 9
IMPORTANT SAFETY INFORMATION
Read and follow all safety messages and instrucons in this
manual.
This is the safety alert symbol. It is used to alert you to
potenal physical injury hazards. Obey all safety messages
that follow this symbol to avoid possible property damage,
serious injury or death. Do not remove any permanent
instrucons, labels, or the data plate from either the outside
of the water heater or on the inside of the access panels. Keep this manual
near the water heater.
WARNING! If the informaon in these instrucons 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.
An odorant is added by the gas supplier to the gas used by this water heater.
This odorant may fade over an extended period of me. Do not depend upon
this odorant as an indicaon of leaking gas. We recommend installing a fuel
gas and carbon monoxide detector.
This product is cerfied to comply with a maximum weighted average of
0.25% lead content.
DANGER indicates a hazardous
situaon that, if not avoided, will
result in death or serious injury.
WARNING indicates a hazardous
situaon that, if not avoided, could
result in death or serious injury.
CAUTION indicates a hazardous
situaon that, if not avoided, could
result in minor or moderate injury.
NOTICE indicates pracces not
related to physical injury.
DANGER
WARNING
CAUTION
NOTICE
*Operate the Pressure Relief Valve
annually and inspect Pressure Relief
Valve every 2-4 years (see the label
on the Pressure Relief Valve for
maintenance schedule). If no label is
attached to the Pressure Relief Valve,
follow the instructions in the Pressure
Relief Valve Maintenance section of this
manual.
See the Maintenance section for more
information about maintaining this
water heater.
Important informaon to keep
Fill out this secon and keep this manual
in the pocket of the water heater for
reference.
Date Purchased:
Model Number:
Serial number:
Maintenance performed:* Date:

10 • Residenal Gas Tankless Water Heater Use and Care Guide
To reduce the risk of property
damage, serious injury or death, read
and follow the precauons below,
all labels on the water heater, and
the safety messages and instrucons
throughout this manual.
RISKS DURING
INSTALLATION AND
MAINTENANCE
Liing Risk
WARNING! The
water heater is
heavy. Follow these
precauons to reduce the risk of
property damage, injuries from liing
or impact injuries from dropping the
water heater.
• Use at least two people to lithe
water heater.
• Be sure you both have a good grip
before liing.
• Use an appliance dolly or hand truck
to move the water heater.
Explosion Risk
WARNING! Read the
water heater’s data
plate to determine the type of gas
required. Failure to follow these
instrucons can result in serious
injury or death from explosion, fire
or carbon monoxide poisoning.
• Do not connect a natural gas water
heater to an L.P. gas supply.
• Do not connect an L.P. gas water
heater to a natural gas supply.
• Use a new gas supply line approved
for Propane or Natural Gas that
meets all local and state/provincial
codes.
• Install a full port shut-offvalve on
the gas supply line.
• Maintain the Pressure Relief Valve
properly. Follow the maintenance
instrucons provided by the manu-
facturer of the Pressure Relief Valve
(label aached to Pressure Relief
Valve). If no label is aached to the
Pressure Relief Valve, follow the
instrucons in the Pressure Relief
Valve Maintenance secon of this
manual. An explosion could occur if
the Pressure Relief Valve or dis-
charge pipe is blocked. Do not cap
or plug the Pressure Relief Valve or
discharge pipe.
Gas Pressure
WARNING! The gas supply
pressure must not exceed the
maximum supply pressure as stated
on the water heater’s data plate. The
minimum supply pressure is for the
purpose of input adjustment. L.P.
gas supply pressure must not exceed
14” water column. Have a qualified
person (licensed plumber, gas
company personnel, or authorized
service technician) check for proper
L.P. gas pressure. L.P. gas pressures
exceeding 14” water column can
result in serious injury or death from
explosion or fire.
RISKS DURING
OPERATION
Scalding Risk
This water heater
can make water hot
enough to cause
severe burns instantly, resulng in
severe injury or death.
• Feel water before bathing or show-
ering.
• To reduce the risk of scalding, install
Thermostac Mixing Valves (tem-
perature liming valves) at each
point-of-use. These valves automa-
cally mix hot and cold water to limit
the temperature at the tap. Mixing
valves are available at your local
plumbing supplier. Follow the man-
ufacturer’s instrucons for installa-
on and adjustment of the valves.
• Water temperatures over 125°F
(52°C) can cause severe burns
instantly or death from scalding. The
water temperature is set at 120°F
(50°C) from the factory to minimize
any scalding risk. Before bathing or
showering, always check the water
temperature. Higher temperatures
increase the risk of scalding, but even
at 120°F, hot water can scald. If you
choose a higher temperature seng,
Thermostac Mixing Valves located
at each point-of-use are parcularly
important to help avoid scalding.
Table 3: Burn/Scald Table
Temperature Time to Produce a
Serious Burn
120°F (49°C) More than 5 minutes
125°F (52°C) 1½ to 2 minutes
130°F (54°C) About 30 seconds
135°F (57°C) About 10 seconds
140°F (60°C) Less than 5 seconds
145°F (63°C) Less than 3 seconds
150°F (66°C) About 1½ seconds
155°F (68°C) About 1 second
For more informaon about changing
the factory temperature seng, refer
to the “Adjusng the Temperature”
secon in this manual.
Even if you set the water heater’s gas
control valve to a low seng, higher
water temperatures may occur in
certain circumstances.
• Water temperature will be hoer if
someone adjusted the set tempera-
ture to a higher seng.
• Should overheang occur or the
burner fail to shut off, turn offthe
manual gas supply valve to the
water heater and call a qualified
person.
IMPORTANT SAFETY INFORMATION

Residenal Gas Tankless Water Heater Use and Care Guide • 11
IMPORTANT SAFETY INFORMATION
To reduce the risk of unusually hot
water reaching the fixtures in the
house, install Thermostac Mixing
Valves at each point-of-use.
If anyone in your home is at parcular
risk of scalding (for example, the
elderly, children, or people with
disabilies) or if there is a local code
or state/provincial law requiring a
certain water temperature at the
hot water tap, these precauons are
parcularly important.
According to a naonal standard
American Society of Sanitary
Engineering (ASSE 1070) and most
local plumbing codes, the water
heater’s thermostat should not be
used as the sole means to regulate
water temperature and avoid scalds.
Water Contaminaon Risk
Do not use chemicals that could
contaminate the potable water supply.
Do not use piping that has been
treated with chromates, boiler seal, or
other chemicals. Suitable for potable
water heang only.
Fire Risk
To reduce the risk of a
fire that could result in
property damage, or
serious injury or death:
• Do not store things that can burn
easily such as paper or clothes next
to the water heater.
• Do not store or use gasoline or other
flammable substances in the vicinity
of this or any other appliance.
• Do not use this appliance if any part
has been in contact with or been im-
mersed in water. Immediately call a
qualified installer or service agency
to replace a flooded water heater.
Do not aempt to repair the unit. It
must be replaced.
Explosion Risk
High pressures in the
water heater can cause
an explosion resulng in property
damage, serious injury or death. A
Pressure Relief Valve is required to
be installed on the water heater. A
Pressure Relief Valve is supplied
with X3® models and shall be field
supplied for M models. Addional
pressure protecve equipment may
be required by local codes.
A naonally recognized tesng
laboratory maintains public inspecon
of the valve producon process
and cerfies that it meets the
requirements for Relief Valves for Hot
Water Supply Systems, ANSI Z21.22.
The Pressure Relief Valve’s relief
pressure must not exceed the working
pressure rang of the water heater as
stated on the rang plate.
Carbon Monoxide Risk
WARNING! This
water heater
operates by burning
gas. Carbon
monoxide is a
colorless, odorless,
gas that is a by-product of burning of
fuels such as coal, wood, charcoal,
oil, kerosene, propane, and natural
gas. Breathing excessive and
abnormal amounts of carbon
monoxide can cause carbon
monoxide poisoning, resulng in
serious injury or death. This water
heater must be supplied with
adequate combuson air and must
be properly vented to the outdoors.
Have a qualified person (licensed
plumber, authorized gas company
personnel, or authorized service
technician) install the venng system
using these installaon instrucons.
Install a fuel gas and carbon
monoxide detector in the living areas
of your home.
• Failure to follow these instrucons
can result in serious injury or death
from carbon monoxide poisoning.

12 • Residenal Gas Tankless Water Heater Use and Care Guide
Read Before
Installaon
1 Review all of the instrucons
before you begin work.
Improper installaon can
damage the water heater, your home
and other property, and can present
risks of serious injury or death.
2 This water heater is designed
as a Category IV, posive
vented stac pressure water
heater (vent gas temperatures may
cause excessive condensate
producon in the vent,) which takes
its combuson air either from the
installaon area or from air ducted to
the unit from the outside. This water
heater must be installed:
• Following all local codes, or in the
absence of local codes, follow the
current edion of ANSI Z223.1/NFPA
54, Naonal Fuel Gas Code in the
USA or B149.1, Natural gas and pro-
pane installaon code in Canada.
• For installaon in manufactured
homes (mobile homes) follow the
current edion of The Manufactured
Home Construcon and Safety Stan-
dard, Title 24 CFR, Part 3280 and/or
CSA Z240 MH Series, Manufactured
Homes.
• Follow the electrical code require-
ments of the local authority having
jurisdicon. In the absence of such
requirements, follow the current
edion of the Naonal Electrical
Code ANSI/NFPA 70 in the U.S. or
the current edion of CSA C22.1
Canadian Electrical Code Part 1 in
Canada.
These are available from the
following:
CSA Group, Inc.
United States:
8501 East Pleasant Valley Road
Cleveland, OH 44131
Canada:
178 Rexdale Blvd.
Toronto, ON
Canada M9W 1R3
Naonal Fire Protecon Associaon
1 Baerymarch Park
Quincy, MA 02269
Check with local code officials about
codes governing this installaon.
Have your installaon inspected by a
code official to ensure the installaon
meets all local codes.
NOTICE: Installaon and service must
be performed by a qualified installer
(for example, a licensed plumber or
gas fier). Otherwise, the warranty
will be void. The installer (licensed
professional) is responsible for the
correct installaon of the water
heater and for compliance with all
naonal, state/provincial, and local
codes.
Massachuses code requires this
water heater to be installed in
accordance with Massachuses
248-CMR 2.00 and 248-CMR 5.00:
State Plumbing Code. Other local and
state/provincial authories may have
similar requirements or other codes
applicable to the installaon of this
water heater.
3 Before you start, check the
following:
Warning! Do not store or use
flammable materials, vapors, or
liquids in the same locaon where
this water heater is installed.
• All gas water heaters require correct
installaon to ensure safe and
efficient operaon. This manual
must be followed exactly. Read the
“Safety Guidelines” Secon.
• Carefully plan the installaon loca-
on of the heater and vent termina-
ons.
• The water heater must be installed
where the proper amount of
combuson air will be available to
it at all mes without obstrucons.
When installed indoors, the water
heater can be direct vented.
• The length of piping between the
water heater and fixture determines
the me it takes for the hot water
to arrive. Consider installing the
water heater closer to the fixtures,
if the plumbing system allows for it.
The water heater should be the first
appliance to access the water line
aer ulies water meter.
• Locate your water heater close to a
drain where water leakage will not
do damage to surrounding areas. As
with any water heang appliance,
the potenal for leakage at some
me in the life of the product does
exist. A drain pan, or other means
of protecon against water damage,
is recommended to be installed
under the water heater in case of
leaks. In addion, you may install
an acve water leak detector with a
shutoffvalve which can turn offthe
water supply in the event of a leak.
The manufacturer is not responsible
for damage due to water leaks. If
you install a drain pan under the
unit, ensure that it will not restrict
the combuson air flow.
• The water heater shall be securely
wall-mounted or mounted on a
stand.
• Maintain proper space for servicing.
Install the unit so that it can be con-
nected or removed easily. Refer to
the "Unit clearances" secon page
17 for proper clearances.
• For outdoor installaons, locate the
water heater in an open , unroofed
area. Maintain 3 in. (76 mm) min-
imum clearance from the leand
right sides of the unit.
• The manufacturer does not recom-
mend installing the water heater
in an ac due to safety issues. See
the installation section for further
information.
GETTING STARTED

Residenal Gas Tankless Water Heater Use and Care Guide • 13
GETTING STARTED
• Failure to observe these warnings
could result in severe personal injury,
death, and/or property damage.
Venng/Combuson:
• Do not install the heater where water,
debris or flammable vapors may get
into the flue terminal. This may cause
damage to the heater and void the
warranty.
• Do not locate your heater in a pit or
locaon where gas and water can
accumulate.
• Do not install the exhaust vent for
indoor and outdoor models within
3. (914 mm) of an overhang.
• Do not install the unit where the ex-
haust vent is poinng into any open-
ing in a building or where the noise
may disturb your neighbors. Make
sure the vent terminaon meets the
required clearance from any doorway
or opening to prevent exhaust from
entering a building. Check local code
requirements prior to installaon.
• Vent terminaon must be at least 2 
(610 mm) away from an inside corner
for both outdoor installaon and
direct-vent installaon.
Outside
corner
Inside
corner
3
min.
2
min.
2
min.
Overhang
Figure 1 - Over hang and Inside Corner
Restricons
• Do not install next to a dryer or any
source of airborne debris that can be
trapped inside the combuson cham-
ber, unless the system is direct-vent-
ed. When direct vented, do not install
the air intake near the dryer vent or
any source of airborne debris.
• Do not common vent this water
heater with any other water heaters
or appliances.
h^ϭŌ;ϯϬĐŵͿŵŝŶ
ĂŶĂĚĂϯŌ;ϵϭĐŵͿŵŝŶ
h^ϭŌ;ϯϬĐŵͿŵŝŶ
ĂŶĂĚĂϯŌ;ϵϭĐŵͿŵŝŶ
h^ϭŌ;ϯϬĐŵͿŵŝŶ
ĂŶĂĚĂϯŌ;ϵϭĐŵͿŵŝŶ
h^ϭϮŝŶ;ϯϬĐŵͿĂďŽǀĞŐƌĂĚĞĂŶĚ
ĂďŽǀĞĂŶƟĐŝƉĂƚĞĚƐŶŽǁůĞǀĞů
ĂŶĂĚĂϭϮŝŶ;ϯϬĐŵͿĂďŽǀĞŐƌĂĚĞ
ŶƟĐŝƉĂƚĞĚƐŶŽǁůĞǀĞů
Figure 2 - Minimum Vent Clearances (Indoor)
h^ϰŌ;ϭϮϮĐŵͿŵŝŶ
h^ϰŌ;ϭϮϮĐŵͿŵŝŶ h^ϰŌ;ϭϮϮĐŵͿŵŝŶ
Figure 3 - Minimum Vent Clearances (Outdoor Venng)

14 • Residenal Gas Tankless Water Heater Use and Care Guide
GETTING STARTED
4 Before you start, be sure you
have the following tools and
supplies:
• Plumbing tools and supplies appro-
priate for the type of water pipes in
your home.
• Thread sealant tape or pipe joint
compound approved for potable
water.
• For homes with water lines using
threaded connectors suitable for the
specific type of plasc pipe used:
CPVC or PEX (cross-linked polyeth-
ylene). Do not use PVC pipe.
• Non-corrosive gas leak detecon
soluon made from hand
dishwashing soap mixed with water
(1 part soap to 15 parts water) or
children’s soap bubbles and a small,
so-bristled brush or approved gas
leak detecon device.
• An appliance dolly or hand truck to
move the water heater.
Recommended Accessories
• Automac water leak detecon and
shut-offdevice
• Thermostac Mixing Valves at each
point-of-use
• Fuel gas and carbon monoxide
detector
Included Items
Table 4: Items Included with your Water Heater
Item Descripon
Manual Installaon Instrucons and Use & Care Guide.
Pressure Relief
Valve
Pressure Relief Valve rated up to 150 psi and the maximum BTU/hr of the
water heater.
(Included with X3® models; Field supplied for M models)
Wall Mounng
Bracket
Kit for mounng water heater contains:
• Mounng Bracket (1x)
• 1/4” x 3” Lag Bolts (4x)
Screws for
Vent Ports
Screws to secure the vent piping to the vent ports. See “Installing the Vent
Pipe.” on page 23.
• 3/16” x 3/8” Vent Screw (x2)
X3® Cartridge
Screws (x1) (x2)
Screws to secure the X3® Cartridge
• M4-12mm (1x)
• M4-25mm (2x)
Cascading Cable
Cascading Cable for electronically connecng tankless water heaters in
series for greater output.
• P/N 100371915
Fuel Conversion
Kit
Convert heater from Natural Gas (NG) to Liquid Propane (LP). Kit contains:
• LP Diaphragm
• Gas Conversion Label (1x)
• Gas Conversion Instrucon (1x)
• Plasc Retainer (1x)
2” Bird Screens
Bird screen to restrict small animals, birds, pests, and other foreign objects
from entering the vent system. Kit contains 2 screens sized for 2” vent
elbows.

Residenal Gas Water Heater Use and Care Guide • 15
Available Accessories
Table 5: Accessories available for your Water Heater
Item Descripon
X3® Cartridge
Add to an M model heater to prevent scale buildup and eliminate the need
for annual descaling maintenance.
• P/N 100368986
Wi-Fi Module Kit
Wi-Fi Module for electronically connecng tankless water heaters to the
Internet and adapter to connect to the water heater.
• P/N 100371922
Remote
Temperature
Controller
Remote Temperature Controller with 10 . (3m) cable.
• P/N 100371898
Communicaon
Cables
Communicaon Cable Extensions for Remote Temperature Controller, Wi-Fi
Module, or On-Demand Receiver.
• P/N 100371899 for 10 . (3 m)
• P/N 100371900 for 32 . (10 m)
Remote
Recirculaon Kit
Remote Recirculaon Kit engages heater and recirculaon at a touch of a
buon for on-demand hot water. Kit contains:
• P/N 100371920 for One Receiver and Two Buon Kit
• P/N 100371921 for One Receiver and Three Buon Kit (Not Pictured)
Individual Spare
Buons
Add more Remote Recirculaon Buons to a system as needed. Add up to
a maximum of 30 buons.
• P/N 100371913
Cartridge Freeze
Protecon
Cartridge Freeze Protecon can add an extra layer of freeze protecon to
external cartridge.
• P/N 100325654 for X3®Models
• P/N 100371918 for Bypass Models
Pipe Cover
Pipe Cover protects plumbing connecons to the heater while improving
the appearance of the installaon. Affixes to boom of heater.
• P/N 100374697
GETTING STARTED

16 • Residenal Gas Water Heater Use and Care Guide
Item Descripon
Neutralizer
Assembly Kit
Neutralizer Assembly neutralizes the condensate (acidic water) that forms
in the secondary heat exchanger of the water heater. It connects to the
condensate drain port of the water heater by using connectors included
with the neutralizer kit.
• P/N 100112159
Outdoor Vent Cap
Kit
Outdoor Installaon Kit containing the outdoor vent cap and User Interface
• P/N 100369060
Crossover Valve Kit
Crossover valve for recirculaon systems without a dedicated return line.
The kit includes a lead free Stainless/Brass Crossover Valve, Brass Tee and
2 . Flex Hose.
• P/N 100327167
Isolaon Valve
Kit with Pressure
Relief Valve
Isolaon Valve supports roune maintenance and allows for draining
and flushing the heater; whereas, the Pressure Relief Valve, as the name
implies, serves to limit internal pressure in the system.
• P/N 100112156
GETTING STARTED

Residenal Gas Tankless Water Heater Use and Care Guide • 17
Installaon Environment
Proper mounng and clearance
The water heater shall be securely
mounted on a wall that can support
the weight of the water heater. A wall
mounng bracket is supplied with the
water heater to securely mount the
water heater to wall studs. The water
lines, gas line, condensate drain line,
and pressure relief valve discharge
line shall be supported using field
supplied pipe hangers. The water
heater shall not bear the weight of
these lines. The water heater requires
proper installaon clearance for
operaon and service as described in
Unit Clearances secon.
Warning! The installer (licensed
professional) is responsible for the
correct installaon of the water
heater and for compliance with all
naonal, state/provincial, and local
codes.
Atmosphere temperature
Install the water heater in a
heated area where below freezing
temperatures cannot occur. A pipe
cover is recommended when the
water heater is installed outdoors
because it provides beer protecon
from the elements. The warranty will
not be covered if the water heater is
damaged due to freezing. See ”Freeze
Protecon System” on page 54.
Combuson air supply
The water heater requires fresh
combuson air and should be
free of corrosive elements and
flammable vapors. If it is installed in
a contaminated area or in a confined
area, direct venng installaon is
recommended.
Proper venlaon
For proper operaon the water heater
must be vented in accordance with
the secon “Venng” of the current
edion of the ANSI Z223.1/NFPA 54,
Naonal Fuel Gas Code in the United
States and/or Secon 8 of the B149.1,
Natural gas and propane installaon
code in Canada, as well as applicable
local building codes.
Condensate Drain line
The condensate produced is acidic.
Drain the condensate in accordance
with all local codes and common
safety pracces.
Unit Clearances
Warning! Maintain all clearances
around the water heater. Failure
to do so could create a fire hazard,
potenally leading to death, serious
injury, and/or property damage.
Indoor
Top:
12 in (305 mm)
Side:
3 in (76 mm)
Front:
4 in (102 mm)
Bottom:
18 in (458 mm)
Back:
0.5 in (13 mm
)
Side:
3 in (76 mm)
Figure 4 - Indoor Clearances
Top:
12 in (305 mm)
Side:
3 in (76 mm)
Front:
4 in (102 mm)
Bottom:
18 in (458 mm)
Back:
0.5 in (13 mm)
Side:
3 in (76 mm)
Overhang:
36 in (914 mm)
Figure 5 - Outdoor Clearances
It is recommended that the front
should have 24 inches (610 mm) of
clearance for maintenance.
Mounng the Water
Heater
1. Secure the wall mounng bracket
with the four supplied lag bolts to
the wall studs. See Figure 6. DO
NOT secure to the drywall only.
NOTICE: The supplied fasteners
are for wood studs only. When
mounng on any other surface
use fasteners approved for that
wall material/construcon. Make
sure to level the bracket.
16” (406.4 mm) Center
New Construction Configuration Shown:
Drywall cut away to show horizontal bracing.
Wall Stud Wall Stud
Horizontal Blocking - Top
Horizontal Blocking - Bottom
Screws
Figure 6 - Wall bracket installaon.
1. Hang the water heater on the wall
bracket. See Figure 7.
Wall
Bracket
Figure 7 - Mounng the water heater.
2. Secure the water heater firmly
fastening appropriate screws
into the upper bracket/boom
brackets of the water heater and
wall. NOTICE: these screws are
not provided.
Securewithscrews.
Securewithscrews.
Figure 8 - Use mounng screws.
INSTALLATION

18 • Residenal Gas Tankless Water Heater Use and Care Guide
INSTALLATION
Combuson Air and
Venng Installaon
Combuson Air
Before installing the water heater, you
must determine the amount of air
needed to supply this water heater
and any other gas appliances in the
same area and provide adequate air
for combuson and venlaon. This
secon does not apply if the water
heater is direct vented. Consult a
qualified person if you’re unsure of
the proper way to supply air to your
water heater.
WARNING! This gas water heater
requires an adequate source of
clean air for combuson and
venlaon. Without sufficient air,
your water heater will have frequent
outages and may emit excessive
and abnormal amounts of carbon
monoxide.
Before beginning:
Calculate total BTU/HR rang of all
appliances.
To calculate the combuson air and
venlaon required, add up the total
BTU/HR rangs of all gas burning
appliances (e.g., water heaters,
furnaces, clothes dryers) in the same
area.
Your water heater’s BTU/HR rang
is on the data plate, located next to
the gas control valve/thermostat.
The BTU/HR rangs should be on the
other appliances’ data plates. If you
have trouble determining the BTU/HR
rangs, contact the manufacturer or
have a qualified person determine the
venlaon requirements.
NOTICE: If you are replacing your
old water heater with one that has a
higher BTU/HR rang, the amount of
venlaon required may be greater.
Example:
Gas Burning Appliance BTU/HR Rang
Gas Water Heater 199,000
Furnace 75,000
Dryer 20,000
Total 294,000
Your Appliances:
Gas Burning Appliance BTU/HR Rang
Gas Water Heater
Total
Opon A: Installaon without
outside venlaon (not
recommended)
Venlaon with outdoor air is
recommended for all installaons.
Even if the water heater is installed in
a large, open room inside the house,
outdoor air is usually needed because
modern homes are very ghtly sealed
and oen do not supply enough air
to the water heater. However, when
installed in a large indoor space, it
may be possible to provide enough air
without outside venlaon. If you are
unsure if your installaon locaon has
enough venlaon, contact your local
gas ulity company or code officials
for a safety inspecon.
The following instrucons will help
determine if it may be possible to
install without outside venlaon. If
there is not enough venlaon, you
will need to venlate with outside air.
Check for Chemicals:
Installaons where corrosive
chemicals may be present require
outside air. Air for combuson and
venlaon must be clean and free of
corrosive or acid-forming chemicals
such as sulfur, fluorine, and chlorine.
Venlaon with outside air will reduce
these chemicals, but it may not
completely eliminate them. Failure
due to corrosive chemicals is not
covered by the warranty. Examples of
locaons that require outside air due
to chemicals include:
• Beauty salons
• Photo processing labs
• Indoor pools
• Laundry, hobby, or crarooms
• Chemical storage areas
Products such as aerosol sprays,
detergents, bleaches, cleaning
solvents, gasoline, air fresheners,
paint and varnish removers, and
refrigerants should not be stored or
used near the water heater.
A1: Calculate the air volume of
the room
Air requirements depend on the size
of the room.
Floor Area (square feet) x Ceiling
Height (feet) = Room Volume (cubic
feet)
If there are large objects in the
room (e.g., refrigerator, furnace,
car), subtract their volume from the
volume of the room to get a beer
esmate of the air available.
Room Volume – Object Volume = Air
Volume
A2: Calculate required air
volume
A water heater installed in an
unconfined space, such as an ac or
garage, requires that the space be at
least 50 cubic feet per 1,000 BTU/HR
of the total input for all gas burning
appliances in the same area.
[Total BTU/HR/1000] x 50 = Cubic feet
of air required.

Residenal Gas Tankless Water Heater Use and Care Guide • 19
INSTALLATION
Example:
(294,000 / 1000) x 50 = 14,700
If the air volume of the room is less
than the required air volume, you
must provide two permanent outside
air openings that draw in sufficient air.
Use Opon B.
If the air volume of the room is
greater than the required air volume,
it may be possible to install the water
heater without outside venlaon.
A3: Check that combuson
venlaon is adequate
Because modern homes are oen
well-sealed to prevent dras, a
large room may not provide enough
combuson air without venlaon.
Confirm that your installaon has
enough combuson air.
Opon B: Installaon with
outside venlaon
Venlaon with outside air is
recommended, and, for most
installaons, is needed. There may be
exisng venlaon that is adequate,
or you may need to add more
venlaon.
Supplying outside air typically requires
two openings. One opening must be
within 12 inches from the floor and
the second opening must be within
12 inches from the ceiling. Although
a single opening is not preferred, you
may use a single opening to outside
air if the minimum free area is sized
according to Table 6. Two openings
must be used when venlang with
air from another room.
B1: Determine type of
venlaon
There are several types of venlaon
that can be used:
1. Direct to outdoors
2. Vercal ducts
3. Horizontal ducts
4. Single opening (not recommend-
ed); must be at least 100 square
inches. Not appropriate for
confined spaces smaller than 50
cubic feet per 1,000 BTU/HR as
calculated in secon A or when
geng air from another room.
5. From a larger room inside the
house (not recommended —
refer to secon A to determine
if the combined volume of the
room may be adequate)
B2: Determine minimum free
area required for each vent
opening
The size of the vent openings depends
on the total BTU/HR rang of all
appliances in the space (use your
calculaon from “Before Beginning”)
and the type of vent used. Table 6
provides the minimum free area for
each vent opening depending on the
type of venlaon.
B3: Calculate minimum size of
vent openings and ducts
The vent cross-seconal area needed
to provide the free area depends on
the covering on the vent openings.
Typical vents use louvers or grilles to
protect the opening. The louver or
grille itself blocks some of the free
area, so the opening may need to be
larger to meet the minimum free area
requirements.
Use the following formula to calculate
the required cross-seconal area:
Cross-seconal area = minimum free
area required ÷ percent free area of
covering (in decimals – e.g., 60% = .6)
For example, an installaon area that
requires openings with 100 square
inches of free area would need 134
square inch openings if using metal
louvers rated at 75% free area
(100 sq. in. ÷ .75 = 134 sq. in.).
If you do not know the % free area for
your louver or grille, use the following
values:
• For wood louvers or grilles: 20%
• For metal louvers or grilles: 60%
Follow these rules to ensure that
vents and ducts provide adequate air
flow:
• Each vent opening must be no small-
er than 100 square inches.
• Ducts must have the same cross-sec-
onal area as free area of the
opening.
• Rectangular ducts must have a
minimum dimension of no less than
three inches.
• All screens must have mesh ¼” or
larger.
• Movable louvers must be locked
open or interconnected with the
equipment so that they open auto-
macally during operaon.
• Keep louvers and grilles clean and
free of debris or other obstrucons.
B4: Check that air source is
clean and free of chemicals
Air for combuson and venlaon
must be clean and free of corrosive
or flammable chemicals. A failure due
to corrosive chemicals in the air is not
covered by the warranty. Combuson
air must be free of acid-forming
chemicals such as sulfur, fluorine, and
chlorine. Be sure that air at the vent
inlets is free of such chemicals.
B5: Check that combuson
venlaon is adequate
To confirm that your installaon has
enough combuson air.

20 • Residenal Gas Tankless Water Heater Use and Care Guide
INSTALLATION
Combuson Air Supply Opons
Gable vent
to outdoors
Install above
ŝŶƐƵůĂƟŽŶ
Outlet air to
ĂƫĐϭŝŶ
2
;ϲϱĐŵ
2
)
per 4,000 btu/h
/ŶůĞƚĂŝƌĨƌŽŵ
ƚŚĞĐƌĂǁůƐƉĂĐĞ
KƉĞŶĨŽƵŶĚĂƟŽŶǀĞŶƚ
ŽŶĮŶĞĚ
^ƉĂĐĞ
Alternate
Air Inlet
ϭŝŶ
2
;ϲϱĐŵ
2
)
p
er 4,000 btu/h
Figure 9 - Direct to Outdoors Openings
Two permanent
Openings
1 in2 (6.5 cm2)
per 4,000 btu/h
12” (305 mm)
maximum
12” (305 mm)
maximum
ŽŶĮŶĞĚ
Space
Figure 10 - Direct to outdoors openings. Two
permanent openings.
Outlet air to
ĂƫĐϭŝŶ
2
;ϲϱĐŵ
2
)
per 4,000 btu/h
/ŶůĞƚĂŝƌĚƵĐƚ
ϭŝŶ
2
;ϲϱĐŵ
2
)
per 4,000 btu/h
ŽŶĮŶĞĚ
^ƉĂĐĞ
ϭϮ;ϯϬϱŵŵͿ
ŵĂdžŝŵƵŵ
'ĂďůĞǀĞŶƚ
ƚŽŽƵƚĚŽŽƌƐ
/ŶƐƚĂůůĂďŽǀĞ
ŝŶƐƵůĂƟŽŶ
Figure 11 - Vercal Duct Openings
1 in
2
(6.5 cm
2
)
per 2,000 btu/h
ŽŶĮŶĞĚ
Space
Outlet
Inlet
KƵƚĚŽŽƌ
Air Ducts
1 in
2
(6.5 cm
2
)
per 2,000 btu/h
Figure 12 - Horizontal Duct Openings
ŽŶĮŶĞĚ
^ƉĂĐĞ
1 in
2
(6.5 cm
2
)
ƉĞƌϯϬϬϬbtu/h
ůƚĞƌŶĂƟǀĞ
KƉĞŶŝŶŐ
>ŽĐĂƟŽŶ
Figure 13 - Single Opening
Two permanent
Openings
1 in
2
per
1,000 btu/h
12” (305 mm)
maximum
12” (305 mm)
maximum
ŽŶĮŶĞĚ
Space
Figure 14 - Two permanent openings
Table 6:
Minimum Free Area of Permanent Openings for Venlaon and Combuson Air Supply – Air from outdoor or indoor spaces.
Based on the total BTU/hr input rang for all gas burning appliances within a confined space.
Opening Source Minimum Free Area
Direct to outdoors* 1 in2(6.5 cm2) per 4,000 BTU/hr (See Figure 9 & Figure 10)
Vercal ducts 1 in2(6.5 cm2) per 4,000 BTU/hr (see Figure 11)
Horizontal ducts 1 in2(6.5 cm2) per 2,000 BTU/hr (see Figure 12)
Single Opening 1 in2(6.5 cm2) per 3,000 BTU/hr (see Figure 13)
Two permanent openings
to another room**
1 in2(6.5 cm2) per 1,000 Btu/hr (see Figure 14)
Opening: 100 in2(645 cm2) Min
Minimum dimension of air openings: no less than 3 in (76 mm)
*These openings connect directly with the outdoors through a venlated ac, a venlated crawl space, or through an outside wall.
**United States: For direcon on combining spaces in different stories within the structure, refer to the current edion of the Naonal Fuel Gas Code ANSI
Z223.1/NFPA 54. In Canada, refer to the current edion of B149.1 Natural gas and propane installaon code.