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