A.O. Smith T-H3M-DV User manual

2 Page
Installation Manual
Contents
CONTENTS
Installation Manual
SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
SAFETY GUIDELINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Included accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Venting instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Gas supply and gas pipe sizing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Water connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Condensate drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Electrical connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Temperature remote controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
High-altitude installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
APPLICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
INITIAL OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
OPTIONAL ITEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Owner's Guide
OPERATING SAFETY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
NORMAL OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Display of controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Temperature table of controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Temperature settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Additional features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Freeze protection system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Maintenance and service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Unit draining and filter cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Descaling the unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
COMPONENTS DIAGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
OUTPUT TEMPERATURE CHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
LIMITED WARRANTY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
{ dZ] ]voo]}v uvo ] } (} ]voo]}v ]v Z hv] ^X
NOTICE

3 Page
Installaon Manual
Installation Manual
CONGRATULATIONS
Congratulations and thank you for choosing our tankless water heater.
Before use, we recommend that you read through this safety manual
carefully. Please refer to the back of the manual for details about the
warranty. Keep this manual for future reference.
If you lose the manual, contact the manufacturer or your local
distributor. When you call, please tell us the model number and the
serial number of your unit written on the rating plate of the water
heater.

4 Page
Installation Manual
Specifications
SPECIFICATIONS
*40 psi (0.27 MPa) or above is recommended for maximum flow.
** The Manifold Pressure is the factory setting and Z}o  v} v iuv .
NOTE:
{ Check the rating plate to ensure this product matches your specifications.
{ In accordance with ANSI Z21.10.3, CO emission does not exceed 400 PPM for normal input.
{ dZ uv(  Z ]PZ } ]}v]vU } ZvP  v˙ ]uU ](]]}v } ]Pv
`]Z} v}] v `]Z} ]v]vP }o]P]}vX
D}o 140
 /v}}
(T-H3M-DV)

K}}
~dr,DrK^
Eo ’ /v
(Operating Range) BTU/h Min.: 15,000 Max.: 120,000
W}v /v
(Operating Range) BTU/h Min.: 15,000 Max.: 120,000
’ }vv]}v 1/2" NPT
t }vv]}v 3/4" NPT
t W psi
(MPa) 15 - 150 (0.1 - 1.0)
Eo P
/vo W inch W.C. (kPa) Min. 5.0 (1.2) Max. 10.5 (2.6)
W}v
/vo W inch W.C. (kPa) Min. 8.0 (2.0) Max. 14.0 (3.5)
Dv](}o
W
Natural
Gas inch W.C.
(Pa) 3.30 (820) 2.00 (500)
Propane inch W.C.
(Pa) 3.00 (750) 1.60 (400)
t]PZ lbs. (kg) 50 (22.5) 50 (22.5)
]uv]}v inch H 21-3/4 x W 14 x D 9-1/4
H 552 x W 352 x D 236
mm
/Pv]]}v Electric Ignition
o]
Supply VAC / Hz 120 / 60
Consumption
Operation W / A 53.9 / 0.7
Standby W / A 3.2 / 0.05
Freeze-
Protection W / A 223.9 / 1.94

5 Page
Introduction
Installation Manual
INTRODUCTION
{ This manual provides information necessary for the installation, operation, and maintenance
of the water heater.
{ The model description is listed on the rating plate which is attached to the side panel of the
water heater.
{ Please read all installation instructions completely before installing this product.
{ If you have any problems or questions regarding this equipment, consult the manufacturer or
its local representative.
{ This equipment is an on-demand, tankless water heater designed to efficiently supply endless
hot water for your needs.
{ These Z]PZ((]]v˙ u}o have a built-in secondary heat exchanger that absorbs latent
heat from the exhaust gas.
{ The 140 Indoor (T-H3M-DV) model is only to be installed indoors. The 140 Outdoor (T-H3M-
OS) model is only to be installed outdoors.
{ The principle behind tankless water heaters is simple:
*This diagram illustrates tankless water heater design concepts only and does not accurately
represent the water heater’s physical description.
1. A hot water tap is turned on.
2. Water enters the heater.
3. The water flow sensor detects the water flow.
4. The computer initiates the fan motor and sends a signal to the igniter to create an ignition
spark.
5. The gas ignites and flames appear within the burner chamber.
6. Water circulates through the heat exchanger and then gets hot.
7. Using thermistors to measure temperatures throughout the water heater, the computer
modulates the gas and water valves to ensure proper output water temperature.
8. When the tap is turned off, the unit shuts down.
Burners
Exhaust
Secondary
heat exchanger
Primary
heat exchanger
Igniter
Gas valve
Fan motor
Flow sensor
Condensate
drain port
Gas inlet
Cold water inlet
Thermistor
Hot water outlet
Thermistor
Intake port
Exhaust
Thermistor
Water control
valve
Computer
board

6 Page
SAFETY GUIDELINES
SAFETY DEFINITION
Indicates an imminently hazardous situation which, if not avoided, will result in
death or serious injury.
E’Z
tZE/E’
Indicates an imminently hazardous situation which, if not avoided, could result
in death or serious injury.
hd/KE
Indicates an imminently hazardous situation which, if not avoided, could result
in minor or moderate injury.
GENERAL
X Follow all local codes, or in the absence of local codes, follow the most recent edition of the National
FuelGasCode: ANSIZ223.1/NFPA54intheUSAorCAN/CSAB149.1NaturalGas,PropaneInstallation
Code in Canada.
X Properly ground the water heater in accordance with all local codes or in the absence of local codes,
with the National Electrical Codes: ANSI/NFPA 70 in the USA or CSA standard C22.1 Canada Electrical
Code Part 1 in Canada.
X Carefully plan where you intend to install the water heater. Please ensure:
{ Your water heater will have enough combustible air and proper ventilation.
{ Locate your heaterwherewater leakage willnot damage surroundingareas(please refertop.8).
X Check the rating plate for the correct ’^ dzWU’^ WZ^^hZU tdZ WZ^^hZ v >dZ/
Zd/E’ .
*If this water heater does not match your requirements, } v} ]voo  v }vo `]Z Z uv( -
 .
æX If any problem should occur, turn off all hot water taps and turn off the gas. Then call a trained
technician or the Gas Company or the manufacturer.
tZE/E’
{ 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.
{ Do not store or use gasoline or other flammables, vapors, or liquids in the
vicinity of this appliance.
{ Do not reverse the water and/or gas connections as this will damage the gas
valves and can cause severe injury or death. Follow the diagram on p. 22
when installing your water heater.
{ Do not use this water heater if any part has been in contact with or been
immersed in water. Immediately call a licensed plumber, a licensed gas fitter,
or a professional service technician to inspect and/or service the water heater
if necessary.
{ Do not disconnect the electrical supply if the ambient temperature will drop
below freezing. The Freeze Protection System only works if the water heater
has electrical power. The heat exchanger will not be covered under warranty
if it is damaged due to freezing. Refer to the section on the Freeze Protection
System on p. 40 for more information.
Installation Manual
Safety Guidelines

7 Page
Installation Manual
INSTALLATION GENERAL
X Follow all local codes, or in the absence of local codes, follow the most recent edition of the National
Fuel Gas Code: ANSI Z223.1/NFPA 54 in the USA or CAN/CSA B149.1 Natural Gas, Propane Installation
Code in Canada.
X All gas water heaters require careful and correct installation to ensure safe and efficient operation.
This manual must be followed exactly. Read the “Safety Guidelines” section.
X The manifold gas pressure is preset at the factory. It is computer controlled and should not need
adjustment.
X Maintain proper space for servicing. Install the water heater so that it can be connected or removed
easily. Refer to the "Clearances" section on p. 9 for proper clearances.
æXThe water heater must be installed in a location where the proper amount of combustible air will be
available to it at all times without obstructions.
X The electrical connection requires a means of disconnection, to terminate power to the water heater
for servicing and safety purposes.
X Do not install the water heater where the exhaust vent is pointing into any opening in a building or
where the noise may disturb your neighbors. Make sure the vent termination meets the required
distanceby local code from any doorway or opening to prevent exhaust from entering a building (refer
to p. 17 to 19).
X Particles from flour, aerosols, clothes dryers and other airborne contaminants may clog the air vent,
build up and reduce the functions of the rotating fan, cause improper burning of the gas, or cause
damagetothewaterheater. Regularlyensurethattheareaaroundthewaterheaterisdust- ordebris-
free. Regular maintenance is recommended for these types of environments. Sealed combustion is
recommended too.
ıX The 140 Indoor (T-H3M-DV) model is to be installed indoors only. The model is equipped with a
thermistor and hi-limit switch for the exhaust gas, detecting excess temperatures within the flue and
enablingthewaterheatertosafelystopoperationifneeded. Thesecomponentsarealwaysmonitoring
exhaust gas conditions in order to prevent heat damage to ABS, PVC, CPVC, or Polypropylene (Plastic)
venting if ABS, PVC, CPVC, or Polypropylene is used. If the exhaust gas temperature exceeds 140 °F
(60 °C) these components will enable the water heater to safely stop operation. (These components
are not installed on the outdoor model since the exhaust vent is built-in.)
{ TheIndoormodelrequires3 inch, or4inchdiameterintakeair supplypipe. Theintakepipemust
be sealed airtight.
{ Air supply pipe can be made of aluminum flexible tube, ABS, PVC, CPVC, Polypropylene,
corrugatedstainlesssteel,orCategorylll /IV stainlesssteel. Regardingexhaustpipe,please refer
to p.11 for detailed information.
{ Sidewall venting is recommended for the Indoor model. Vertical venting (roof termination) is
acceptable.
{ The manufacturer recommends running the exhaust vent and the intake pipe as parallel as possible.
X The 140 Outdoor (T-H3M-OS) model is only to be installed outdoors and only in the area with mild,
temperate climates.
The Outdoor model shall be wall-mounted or mounted on a stand. Locate the Outdoor model in an
open, unroofed area and maintain the minimum clearances. (Refer to p.9.)
Installaon

8 Page
Installaon
Installaon Manual
{ /voo]}v v ] u  (}u ˙  o](] ]voo ~(} ˘uoU 
o]v ou } P (]U }Z`] Z `v˙ `]oo }]X
{ dZ ]voo ~o]v }(]}vo ] }v]o (} Z } ]voo]}v }(
Z ` Z v (} }uo]v `]Z oo v]}voU l}]v]oU v o}o
}X
{ dZ uv( } v} }uuv ]voo]vP Z ` Z ]v  ] }
o}]}v `Z P v ` v uoX
{ Do not have the vent terminal pointing toward any operating window, door, or
opening into a building.
{ Do not install the water heater next to any source of airborne debris, such as a
clothes dryer and a vent that can cause debris to be trapped inside the combustion
chamber, unless the system is direct-vented.
{ dZ uv( } v} }uuv ]voo]vP Z ` Z ]vv ] 
} (˙ ]X If you install the water heater in an attic:
{ Make sure the water heater will have enough combustion air and proper
ventilation.
{ Keep the area around the water heater clean. When dust collects on the flame
sensor, the water heater will shut down on an error code.
{ Place the water heater in a location that provides easy access for service and
maintenance.
{ A drain pan, or other means of protection against water damage, is required to
be installed under the water heater in case of leaks.
{ It is recommended to direct vent the heater.
tZE/E’
{ uP  ˙ ` o]˙ ] v} } ˙ Z `v˙X
{ Only potable water or potable water / glycol mixtures can be used with this
water heater. Do not introduce pool or spa water, or any chemically treated
water into the water heater.
{ Water hardness levels must not exceed 7 grains per gallon (120 ppm) for single
family domestic applications or more than 4 grains per gallon (70 ppm) for
all other types of applications. Water hardness leads to scale formation and
may affect / damage the water heater. Hard water scaling must be avoided or
controlled by proper water treatment.
{ Water pH levels must be between 6.5 and 8.5
{ Well water must be treated.
{ Do not install the water heater where water, debris, or flammable vapors may get
into the flue terminal.
{ Although the water heater is designed to operate with minimal sound, Z 
uv( } v} }uuv ]voo]vP Z ` Z }v  `oo iv
}  }}uU  }  }}u Z ] ]vv (} ] ˙  } u]]}vU  .
{ Locate your heater close to a drain where water leakage will not do damage to
surrounding areas. As with any water heating appliance, the potential for leakage
at some time in the life of the product does exist. The manufacturer will not be
responsibleforanywaterdamagethatmayoccur.Ifyouinstalla drainpan underthe
water heater, ensure that it will not restrict the combustion air flow.
hd/KE

9 Page
Installaon
Installaon Manual
INCLUDED ACCESSORIES
Check that these items below are included with the water heater.
/voo]}v Dvo
v K`v[ ’] du Zu} }v}oo l] K}} u}o }vo˙ ] ^v /v}} u}o }vo˙
Qty: 1 Qty: 2
Qty: 1
*For more information on optional items, please refer to p.32 to 33.
CLEARANCES
Maintain all clearances around
the water heater.
D}o d} }}u &}v l ^]
140 Indoor
(T-H3M-DV) 12 in. (305 mm) 12 in. (305 mm) 4 in.* (102 mm) 1 in. (25 mm) 3 in. (76 mm)
140 Outdoor
(T-H3M-OS) 36 in. (914 mm) 12 in. (305 mm) 24 in. (610 mm) 1 in. (25 mm) 3 in. (76 mm)
*24 inches recommended for maintenance
Top
Back
Side
Side
Front
B}'}u
Do not install this water heater under an
overhang less than 3 ft. (914 mm) from its top,
top of exhaust part, or eaves. The area under
an overhang must be open to three sides.
(Outdoor models only)
Do not install the water heater exhaust port
within 1 ft. (305 mm), in the USA, of any air
intake or building opening, and within 3 ft. (914
mm), in Canada, of any air intake or building
opening. (Outdoor models only) (Refer to p.17).
3 ft.
(914 mm)
exhaust port
A
A: 1 ft. (305 mm) USA/3ft.(914mm)Canada
AA

10 Page
Installaon
Installaon Manual
VENTING INSTRUCTIONS
For the 140 Indoor (T-H3M-DV) model
-General-
{ Improper venting of this appliance can result in excessive levels of carbon
monoxide which can result in severe personal injury or death.
{ Improper installation can cause nausea or asphyxiation, severe injury or death
from carbon monoxide and flue gases poisoning. Improper installation will
void product warranty.
E’Z
When installing the vent system, all applicable national and local codes must be
followed. If you install thimbles, fire stops or other protective devices and they
penetrate any combustible or noncombustible construction, be sure to follow all
applicable national and local codes.
hd/KE
The Indoor model must be vented in accordance with the section “Venting of Equipment" of the latest
edition of the National Fuel Gas Code: ANSI Z223.1/NFPA 54 in the United States and/or Section 7 of the
CAN/CSA B149.1 Natural Gas and Propane Installation Code in Canada, as well as applicable local building
codes.
The use of venting materials approved for Category III/IV appliances is recommended whenever possible.
However, the Indoor model may also be vented with plastic pipe materials such as ABS, PVC, CPVC, or
Polypropylene. &} ]oU o ( } Z ˘Z sv ~^U WsUWsU } W}o˙}˙ov sv
]}v }v X X Vent installations in Canada which utilize plastic vent systems must use venting that
complies with ULC S636.
’vo o (} v]vP ` Z W
{ Place the water heater as close as possible to the vent termination.
{ The vent collar of the water heater must be fastened directly to an unobstructed vent pipe.
{ Do not weld the vent pipe to the water heater’s vent collar.
{ Do not cut or alter the vent collar of the water heater.
{ The vent must be easily removable from the top of the water heater for normal service and
inspection of the unit.
{ The water heater vent must not be connected to any other gas appliance or vent stack.
{ Avoid using an oversized vent pipe or using extremely long runs of the pipe.
{ For rooftop venting, a rain cap or other form of termination that prevents rain water from
entering into the water heater must be installed.
{ Do not terminate the vent into a chimney. If the vent must go through the chimney, the vent
must run all the way through the chimney with approved vent pipe.
Water heater vent terminator must be at least 2
ft. (610 mm) away from an inside corner for both
outdoor installation and direct-vent installation.
Inside
Corner
2 ft.
(610 mm)