Takagi T-K4U-IN User manual

Gas Tankless Water HeaterTM
Suitable for potable water heating and space-heating*
* Please refer to local codes for space-heating compliance.
FEATURING
 • ENDLESSHOTWATER
 • ON-DEMANDUSAGE
 • COMPACT,SPACESAVING
 • ENERGYCONSERVATION
 • COMPUTERIZEDSAFETY
 • NOPILOTLIGHT
 • Satisfiesthe2012SCAQMDRule
1146.2forUltra-LowNOx
Emissions
 • EASY-LINKSYSTEMAND
MULTI-UNITSYSTEM
(510U (T-D2U) model only)
Ifyouhaveanyquestions,please
callorwriteto:
500TennesseeWaltzParkway
AshlandCity,TN37015
TollFree:1-877-737-2840
On-Demand Water Heater
Installation Manual and Owner’s Guide
- 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electric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.
WARNING
If the information in these
instructions is not followed
exactly,afireorexplosionmay
resultcausingpropertydamage,
personalinjuryordeath.
Models
• 110U Outdoor (T-KJr2U-OS)
• 310U Outdoor (T-K4U-OS)
• 510U Outdoor (T-D2U-OS)
• 110U Indoor (T-KJr2U-IN)
• 310U Indoor (T-K4U-IN)
• 510U Indoor (T-D2U-IN)
ANSIZ21.10.3andCSA4.3
510U(T-D2U)
modelonly

2Page
CONTENTS
Installation Manual
SPECIFICATIONS.......................................................................................................................... 4
INTRODUCTION .......................................................................................................................... 5
SAFETY GUIDELINES.................................................................................................................... 6
INSTALLATION............................................................................................................................. 7
General.....................................................................................................................................7
Clearances................................................................................................................................9
Included accessories................................................................................................................9
Optional items..........................................................................................................................9
Warning for installations........................................................................................................11
High-altitudeinstallations......................................................................................................12
Ventinginstructions...............................................................................................................13
Gas supply and gas pipe sizing...............................................................................................18
Water connections................................................................................................................20
Electrical connections............................................................................................................21
Temperature remote controller............................................................................................22
Easy-Link System....................................................................................................................25
Multi-UnitSystem..................................................................................................................29
APPLICATIONS............................................................................................................................30
INITIAL OPERATION...................................................................................................................32
Owner's Guide
OPERATING SAFETY .................................................................................................................. 34
NORMAL OPERATION ............................................................................................................... 36
General..................................................................................................................................36
Temperaturesettings.............................................................................................................37
Flow.......................................................................................................................................40
Freeze protection system.......................................................................................................40
Maintenance and service.......................................................................................................41
Unit draining and filter cleaning............................................................................................41
TROUBLESHOOTING...................................................................................................................42
General...................................................................................................................................42
Error codes............................................................................................................................44
COMPONENTSDIAGRAM...........................................................................................................47
PARTS LIST..................................................................................................................................51
OUTPUT TEMPERATURE CHART....................................................................................................54
LIMITED WARRANTY..................................................................................................................55
Contents

3Page
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 product name and the
serial number of your unit written on the rating plate of the water
heater.

4Page
Model 110U
Indoor
(T-KJr2U-IN)
110U
Outdoor
(T-KJr2U-OS)
310U
Indoor
(T-K4U-IN)
310U
Outdoor
(T-K4U-OS)
510U
Indoor
(T-D2U-IN)
510U
Outdoor
(T-D2U-OS)
Natural Gas Input
(Operating Range) BTU/h Min.: 15,000 Max.: 140,000
Min.: 15,000
Max.: 190,000
Min.: 15,000
Max.: 199,000
Gas Connection 3/4" NPT
Water Connections 3/4" NPT
Water Pressure* psi
(Mpa) 15 - 150 (0.1 - 1)
Natural gas
Inlet Pressure
" W.C.
(kPa)
Min. 5.0 (1.24)
Max. 10.5 (2.61)
Manifold
Pressure**
Natural
Gas
" W.C.
(Pa)
1.8
(448)
1.5
(373)
3.0
(747)
2.9
(722)
3.2
(796)
3.05
(759)
Weight lbs. (kg) 37 (16.9) 39 (17.9)
Dimensions inch H 20.5 x W 13.8 x D 8.5
H 520 x W 351 x D 216
mm
Ignition Electric Ignition
Electric
Supply VAC / Hz 120 / 60
Consumption
Operation W / A 52.1 / 0.54 75.8 / 0.83 81.6 / 0.86
Standby W / A 5.4 / 0.08 5.5 / 0.08 6.5 / 0.09
Freeze-
Protection W / A 131 / 1.1 131 / 1.1 132 / 1.1
SPECIFICATIONS
*The maximum flow may need water pressure equal to or above 40 psi.
** The Manifold Pressure is the factory setting and generally should not need adjustment.
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.
• The manufacturer reserves the right to discontinue, or change at any time, specifications or designs
without notice and without incurring obligations.
Specicaons
Installaon Manual

5Page
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.
• The 110U Indoor (T-KJr2U-IN), 310U Indoor (T-K4U-IN) and 510U Indoor (T-D2U-IN) models
are only to be installed indoors (direct-vent (double vent) convertible). The 110U Outdoor
(T-KJr2U-OS), 310U Outdoor (T-K4U-OS) and 510U Outdoor (T-D2U-OS) models are 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 vent collar
Heat exchanger
Gas valves
Fan motor
Flow adjustment valve
Computer board
Thermistor
Cold water inletHot water outlet
Gas inlet
Thermistor
Burners
Flow sensor
Introducon
Installaon Manual

6Page
SAFETY GUIDELINES
SAFETY DEFINITION
GENERAL
1. 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InstallationCode
in Canada.
2. Properly ground the unit 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 Canadian Electrical Code
Part 1 in Canada.
3. 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heaterwherewaterleakagewillnotdamagesurroundingareas.(Pleasereferto
p. 8.)
4. Check the rating plate for the correct GAS TYPE, GAS PRESSURE, WATER PRESSURE and ELECTRIC
RATING.
*If this unit does not match your requirements, do not install and consult with the manufacturer.
5. 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.
WARNING
• 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. 20
when installing your water heater.
• Do not use this appliance 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 unit if
necessary.
• Do not disconnect the electrical supply if the ambient temperature will drop
below freezing. The Freeze Protection System only works if the unit has
electrical power. The warranty will not be covered if the heat exchanger
is damaged due to freezing. Refer to the section on the Freeze Protection
System on p. 40 for more information.
WARNING
Indicates an imminently hazardous situation which, if not avoided, could result
in death or serious injury.
CAUTION
Indicates an imminently hazardous situation which, if not avoided, could result
in minor or moderate injury.
Safety Guidelines
Installaon Manual
Indicates an imminently hazardous situation which, if not avoided, will result in
death or serious injury.
DANGER

7Page
INSTALLATION
GENERAL
1. 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InstallationCodein
Canada.
2. 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.
3. The manifold gas pressure is preset at the factory. It is computer controlled and should not need
adjustment.
4. Maintain proper space for servicing. Install the unit so that it can be connected or removed easily.
Refer to the "Clearances" section on p. 9 for proper clearances.
5. 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.
6. The electrical connection requires a means of disconnection, to terminate power to the water heater
for servicing and safety purposes.
7. Do not install the unit 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 distance by
local code from any doorway or opening to prevent exhaust from entering a building. (Refer to p. 14.)
8. Particles from flour, aerosols, and other contaminants may clog the air vent, build up and reduce
the functions of the rotating fan, cause improper burning of the gas, or cause damage to the water
heater. Regularly ensure that the area around the unit is dust- or debris-free. Regular maintenance is
recommended for these types of environment.
9. For the 110U Indoor (T-KJr2U-IN), 310U Indoor (T-K4U-IN) and 510U Indoor (T-D2U-IN) models:
•These units may be converted to a direct-vent (sealed combustion) appliance by installing
a direct-vent conversion kit Part No. 9007667005 (TK-TV10) which will bring in all required
combustible air from outside the building. When installing the direct-vent conversion kit, please
follow all instructions included with the kit.
•If the water heater is used as a direct-vent appliance, the unit requires a 3 in. (76 mm)
combustible air supply pipe. The intake pipe must be sealed airtight. Air supply pipe can be
made of ABS, PVC, CPVC, Polypropylene, corrugated stainless steel, or Category lll / IV stainless
steel.
•Terminating the venting through a sidewall is recommended for the direct-vent system.
•Running the exhaust vent and the intake pipe parallel is recommended.
•Terminating the exhaust and intake on the same wall/surface is recommended. Terminating in
the same pressure zone allows for pressure balancing, which prevents nuisance shutdowns.
10. The 110U Outdoor (T-KJr2U-OS), 310U Outdoor (T-K4U-OS) and 510U Outdoor (T-D2U-OS) models
only to be installed outdoors and only in the area with mild, temperate climates.
Installaon
Installaon Manual

8Page
• Installation and service must be performed by a qualified installer (for
example, a licensed plumber or gas fitter), otherwise the warranty will be
void.
• The installer (licensed professional) is responsible for the correct installation
of the water heater and for compliance with all national, state / provincial,
and local codes.
• The manufacturer does not recommend installing the water heater in a pit or
location where gas and water can accumulate.
• Do not have the vent terminal pointing toward any operating window, door, or
opening into a building.
• Do not install next to any source of airborne debris, such as a clothes dryer,
that can cause debris to be trapped inside the combustion chamber, unless the
system is direct-vented.
• The manufacturer does not recommend installing the water heater in an attic
due to safety issues. If you install the water heater in an attic:
• Make sure the unit 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.
• If the above conditions cannot be met, use the direct-vent conversion kit
Part No. 9007667005 (TK-TV10).
• Place the unit for 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.
WARNING
• The warranty will not cover damage caused by water quality.
• 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 unit where water, debris, or flammable vapors may get into
the flue terminal.
• The manufacturer recommends using the direct-vent kit when the water
heater is installed in a beauty salon. Some chemicals used in a beauty salon
may affect the flame sensor. Water heater may not work properly.
• Although the water heater is designed to operate with minimal sound, the
manufacturer does not recommend installing the unit on a wall adjacent to a
bedroom, or a room that is intended for quiet study or meditation, etc.
• 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 responsible for any water damage that may occur. If you install a
drain pan under the unit, ensure that it will not restrict the combustion air flow.
CAUTION
Installaon
Installaon Manual

9Page
Top
Back
Boom
Side
Side
Front
Maintain all clearances around
the water heater.
CLEARANCES
Model Top Bottom Front Back Sides
110U Indoor (T-KJr2U-IN)*
310U Indoor (T-K4U-IN)*
510U Indoor (T-D2U-IN)*
12 in.
(305 mm)
12 in.
(305 mm)
4 in.**
(102 mm)
0.5 in.
(13 mm)
3 in.
(76 mm)
110U Outdoor (T-KJr2U-OS)
310U Outdoor (T-K4U-OS)
510U Outdoor (T-D2U-OS)
36 in.
(914 mm)
12 in.
(305 mm)
24 in.
(610 mm)
0.5 in.
(13 mm)
3 in.
(76 mm)
*Standard indoor installations and direct-vent indoor installations have the same clearances.
**24 inches recommended for maintenance.
OPTIONAL ITEMS
#Model
110U
Indoor
(T-KJr2U-IN)
110U
Outdoor
(T-KJr2U-OS)
310U
Indoor
(T-K4U-IN)
310U
Outdoor
(T-K4U-OS)
510U
Indoor
(T-D2U-IN)
510U
Outdoor
(T-D2U-OS)
1. 4" Backflow preventer
and F-F adaptor ✓ ✓ ✓
2. Direct-vent
conversion kit ✓ ✓ ✓
3. Pipe cover ✓ ✓ ✓ ✓ ✓ ✓
4. Recess box ✓ ✓ ✓
5. Sidewall vent
terminator (Hood)
and Wall thimble ✓ ✓ ✓
6. Direct-vent concentric
termination ✓ ✓ ✓
7. Remote controller
for high temperature
mode ✓ ✓
INCLUDED ACCESSORIES
Installaon
Installaon Manual
Check that these items below are included with the water heater.
Installation manual
and Owner’s guide
Temperature
remote controller kit*
Communication cable
510U (T-D2U) model only
Qty: 1 Qty: 1
Qty: 1
*Refer to p. 10 and 22.
9009069005
(TM-RE42)

10 Page
2. Direct-vent conversion kit: 9007667005
(TK-TV10)
This kit can be used
to convert the water
heater from a single
vent system to a direct-
vent (double vent) (or
sealed combustion)
system with a 3 in. (76 mm) intake. Install this
conversion kit in accordance with the installation
instructions and any applicable codes.
The pipe cover protects the plumbing
pipes to the water heater from
unexpected adjustments. This pipe
cover is fixed to the bottom of the
water heater, which hides the plumbing
and improves the visual aspects of the
whole installation for the water heater.
4. Recess box: 9007674005 (TK-RB02)
The recess box will allow for “clean”
installations. The water heater
fits inside the recess box, which
hides and protects the whole water
heater and plumbing. The recess
box will fit in-between most wall
studs.
1. 4” Backflow preventer and F-F adaptor:
9007996005
There are two functions available for this
adaptor, which can be connected with the
water heater and NovaVent venting line
and prevents the backflow of air through
the exhaust vent. This helps prevent
harmful exhaust gases from entering the
home, as well as helping to prevent the
unit from freezing in areas where cold
air can be blown or drawn into the exhaust system.
Install this adaptor in accordance with the installation
instructions that are packaged with the adaptor and
any applicable codes.
5. Sidewall vent terminator (Hood) and Wall thimble:
Used when terminating direct-vent (sealed combustion) systems, with indoor
models that require a 3 in. intake and a 4 in. exhaust. This concentric
termination provides the convenience of only having to make one penetration
through a sidewall instead of two separate penetrations for the intake and
exhaust piping. The termination includes a bird screen, restricting small animals, pests, and foreign
objects from entering into the vent system. This sidewall termination is available in two different sizes,
to cover a wide range of wall thicknesses. For different wall thicknesses,there are two ranges of lengths
available. (Refer to the NovaVent brochure for details.)
Installaon
Installaon Manual
Covering wall thicknesses Part#
Terminator Hood 9007999005
Wall Thimble 4 - 7 in. 9008345005
Wall Thimble 5 - 10 in. 9008346005
Termination + Thimble 4 - 7 in. 9008004005
Termination + Thimble 5 - 10 in. 9008005005
3. Pipe cover: 9007670005 (TK-PC01)
Covering wall thicknesses Part#
5.0 – 10.0 in. 9008147005
12.0 – 18.0 in. 9008148005
6. Direct-vent concentric termination:
They are used when venting out through the wall. These terminations are special stainless steel vents
for gas appliances and are UL listed as Category II, III and IV. For different wall thicknesses, there are two
ranges of lengths available. (Refer to the NovaVent brochure for details.) Install these vent terminations
in accordance with their installation instructions and any applicable local codes.
Wall Thimble
Terminator Hood
7. Remote controller for high temperature mode: 9008172005 (TM-RE40)
This remote controller is for the 510U (T-D2U) and can supply higher temperatures than
the 9009069005 (TM-RE42) that comes with the heater.

11 Page
WARNING FOR INSTALLATIONS
FOR YOUR SAFETY, READ BEFORE INSTALLATION:
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 have the vent terminal pointing toward
any opening into a building. Do not locate your
heater in a pit or location where gas and water
can accumulate.
Do not install this water heater under an
overhang less than 3 ft. (914 mm) from its top
or eaves. The area under an overhang must be
open to three sides (Outdoor models only).
Do not install the water heater vent terminator
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. 16).
Do not install next to a dryer or any source
of airborne debris that can be trapped inside
the combustion chamber, unless the system is
direct-vented.
Prohibited Prohibited
1 ft. (305 mm) USA
3 ft. (914 mm) Canada
1 ft. (305 mm) USA
3 ft. (914 mm) Canada
1 ft. (305 mm) USA
3 ft. (914 mm) Canada
3 ft.
(914 mm)
Installaon
Installaon Manual
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)

12 Page
HIGH-ALTITUDE INSTALLATIONS
Check the elevation where your water heater is installed. Set DIPswitches shown in the table below
depending on the altitude.
Bank of DIPswitches
110U (T-KJr2U) and 310U (T-K4U) models
Computer board
WARNING
DO NOT adjust any DIPswitches on the upper bank for the 510U (T-D2U)
model.
NOTE: The dark squares indicate the direction the DIPswitches should be set to.
Lower bank of DIPswitches
510U (T-D2U) model
Computer board
Installaon
Installaon Manual
Outdoor models
0 to 2,000 ft.
(DEFAULT)
2,000 to
4,000 ft.
4,000 to
6,000 ft.
110U (T-KJr2U) and
310U (T-K4U) models No. 3 : OFF
No. 4 : OFF
No. 5 : OFF
No. 3 : OFF
No. 4 : OFF
No. 5 : ON
No. 3 : ON
No. 4 : OFF
No. 5 : ON
510U (T-D2U) model
(Lower bank of
DIPswitches) No. 2 : OFF
No. 3 : OFF
No. 4 : OFF
No. 2 : OFF
No. 3 : OFF
No. 4 : ON
No. 2 : ON
No. 3 : OFF
No. 4 : ON
OFF
ON
1 2 3 4 5 6 7 8 9 10
OFF
ON
12345678910
OFF
ON
1 2 3 4 5 6 7 8 9 10
OFF
ON
1 2 3 4 5 6
OFF
ON
1 2 3 4 5 6
OFF
ON
1 2 3 4 5 6
Indoor models
0 to 2,000 ft.
(DEFAULT)
2,000 to
3,000 ft.
3,000 to
5,000 ft.
5,000 to
7,500 ft.
7,500 to
10,100 ft.
110U (T-KJr2U) and
310U (T-K4U) models No. 3 : OFF
No. 4 : OFF
No. 5 : OFF
No. 3 : OFF
No. 4 : ON
No. 5 : OFF
No. 3 : OFF
No. 4 : OFF
No. 5 : ON
No. 3 : OFF
No. 4 : ON
No. 5 : ON
No. 3 : ON
No. 4 : ON
No. 5 : ON
510U (T-D2U) model
(Lower bank of
DIPswitches) No. 2 : OFF
No. 3 : OFF
No. 4 : OFF
No. 2 : OFF
No. 3 : ON
No. 4 : OFF
No. 2 : OFF
No. 3 : OFF
No. 4 : ON
No. 2 : OFF
No. 3 : ON
No. 4 : ON
No. 2 : ON
No. 3 : ON
No. 4 : ON
OFF
ON
1 2 3 4 5 6 7 8 9 10
OFF
ON
1 2 3 4 5 6 7 8 9 10
OFF
ON
12345678910
OFF
ON
12345678910
OFF
ON
1 2 3 4 5 6
OFF
ON
1 2 3 4 5 6
OFF
ON
1 2 3 4 5 6
OFF
ON
1 2 3 4 5 6
Altitude
DIPswitches
OFF
ON
12345678910
OFF
ON
1 2 3 4 5 6
Installation altitude
The maximum certified
or allowable installed
altitude is 10,100 ft. for
indoor models and 6,000 ft.
for outdoor models.

13 Page
VENTING INSTRUCTIONS
For indoor models
-General-
The water heater 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 Installation Code in Canada, as well as applicable local building codes.
The manufacturer recommends the NovaVent line. However, the following are also UL listed
manufacturers: ProTech Systems Inc. (FasNSeal), Metal-Fab Inc., and Heat-Fab Inc. (Saf-T Vent).
General rules for venting water heaters are:
• 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 the vent collar of the unit.
• 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 common vent or connect any vent from other appliances to the water heater vent.
General rules for vent terminations:
• Avoid locating the water heater vent termination near any air intake devices. These fans can
pick up the exhaust flue products from the water heater and return them to the building. This
can create a health hazard.
• Locate the vent termination so that it cannot be blocked by any debris, at any time. Most codes
require that the termination must be at least 12 in. (305 mm) above grade, but the installer may
determine if it should be higher depending on the job site condition and applicable codes.
• A proper sidewall termination is recommended when the water heater is vented through a
sidewall.
• Regarding the clearances from the exhaust termination to the air inlet or opening, refer to the
next few pages.
• 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.
DANGER
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.
CAUTION
Installaon
Installaon Manual

14 Page
-Vent length and No. of Elbows-
This is a Category III appliance and must be vented accordingly. The vent system must be sealed airtight.
All seams and joints without gaskets must be sealed with high heat resistant silicone sealant or UL listed
aluminum adhesive tape having a minimum temperature rating of 350 °F (177 °C). For best results, a vent
system should be as short and straight as possible.
• This water heater is a Category III appliance and must be vented accordingly with any 4 in. (102
mm) vent approved for use with Category III or Special BH type gas vent.
• Follow the vent pipe manufacturer’s instructions when installing the vent pipe.
• Do not common vent this appliance with any other vented appliance. (Do not terminate vent
into a chimney. If the vent must go through the chimney, the vent must run all the way through
the chimney with Category III approved or Special BH vent pipe.)
• When the horizontal vent run exceeds 5 ft. (1.5 m), support the vent run at 3 ft. (0.9 m) intervals
with overhead hangers.
• The maximum length of exhaust vent piping must not exceed 50 ft. (15.2 m) (deducting 5 ft. (1.5
m) for each elbow used in the venting system). Do not use more than 5 elbows.
-DIPswitch settings for Vent length-
For Indoor and direct-vent models
Vent type Diameter Max. No. of Elbows Max. Vertical and Horizontal (Total) Vent Length
Intake 3 in. (76 mm) 550 ft. (15.2 m )
Exhaust 4 in. (102 mm) 550 ft. (15.2 m )
*For each elbow added, deduct 5 ft. (1.5m) from max. vent length.
No. of Elbows Max. Vertical or Horizontal Vent Length
050 ft. (15.2 m)
145 ft. (13.7 m)
240 ft. (12.2 m)
335 ft. (10.7 m)
430 ft. (9.1 m)
525 ft. (7.6 m)
Excludes elbow termination, rain caps, or the 4 in. (102 mm) Concentric termination
Set DIPswitches shown in the table below depending on the vent length.
110U Indoor (T-KJr2U-IN)
310U Indoor (T-K4U-IN)
510U Indoor (T-D2U-IN)
(Upper bank of DIPswitches) Vent length
No. 6 : ON
No. 7 : OFF
No. 3 : ON
No. 4 : OFF
0 to 7 ft
No. 6 : ON
No. 7 : ON
No. 3 : ON
No. 4 : ON
8 to 50 ft
(DEFAULT)
OFF
ON
1 2 3 4 5 6 7 8
OFF
ON
1 2 3 4 5 6 7 8
OFF
ON
1 2 3 4 5 6 7 8 9 10
OFF
ON
1 2 3 4 5 6 7 8 9 10
Installaon
Installaon Manual

15 Page
Venng Illustraons-
For the 110U Indoor (T-KJr2U-IN), 310U Indoor (T-K4U-IN) and 510U Indoor (T-D2U-IN) models
For details of the optional items, refer to the Installation manual for each Optional item.
Horizontal Installaon with
Direct-vent concentric terminaon
Wall
Direct-vent
concentric
terminaon
Installaon of Direct-vent
conversion kit with water heater
Water heater
Intake port of Direct-vent
conversion kit
(For details see p. 10.)
Plate of Direct-vent conversion kit
Horizontal Installaon
Hanger
Wall
Sidewall vent
termination
Vertical condensation drain**
Backflow
preventer*
Vercal Installaon
Backflow
preventer*
Rain cap
Roof
Vertical condensation drain**
Roof flashing
Installaon
Installaon Manual
*Backflow preventer (Recommended for freezing weather conditions: 36 °F (2 °C) and below).
**Vertical condensation drain must be installed in accordance with local codes.
Seethepicturebelowfordetailedconnecon
instruconstoDirect-ventconversionkit.
Vercal Installaon
(With direct-venng)
Roof
Vercalcondensaondrain**
Backow
preventer* Fire stop
Roofashing
Rain cap
Horizontal Installaon
(With direct-venng)
Sidewall vent
terminaon
Backow
preventer*
Vercalcondensaon
drain**
Wall
Hanger
Hanger

16 Page
-Vent terminaon clearances-
Canada U.S.A
Direct-vent and other
than Direct-vent
Direct-
vent
Other than
Direct-vent
AClearance above grade, veranda, porch, deck, or
balcony 1 foot 1 foot 1 foot
B Clearance to window or door that may be opened 3 feet 1 foot
4 feet from below or
side opening. 1 foot
from above opening.
CClearance to permanently closed window * * *
D
Vertical clearance to ventilated soffit located above
the vent terminator within a horizontal distance
of 2 feet (61cm) from the center line of the
terminator
* * *
EClearance to unventilated soffit * * *
FClearance to outside corner * * *
GClearance to inside corner * * *
HClearance to each side of center line extended
above meter/regulator assembly 3 feet * *
IClearance to service regulator vent outlet 3 feet * *
J
Clearance to non-mechanical air supply inlet to
building or the combustion air inlet to any other
application
3 feet 1 foot
4 feet from below or
side opening. 1 foot
from above opening.
KClearance to mechanical air supply inlet. 6 feet 3 feet 3 feet
LClearance above paved sidewalk or paved driveway
located on public property 7 feet *7 feet
MClearance under veranda, porch deck, or balcony 1 foot * *
*ForclearancesnotspecifiedinANSIZ223.1/NFPA54orCAN/CSA-B149.1,pleaseuseclearancesinaccordance
with local installation codes and the requirements of the gas supplier.
INSIDE CORNER DETAIL
V
Gas meter / regulator
V
V
V
V
V
V
V
V
V
X
X
X
Vent terminal
Air supply inlet
Area where is not permitted
G
A
E
D
B
L
C
F
B
B
B
BA
J
OPERABLE FIXED
CLOSED
B
H
M
K
OPERABLE
FIXED
CLOSED
I
Installaon
Installaon Manual

17 Page
-For sidewall terminaons-
-For rooop terminaons-
For multiple sidewall exhaust terminations (e.g. multi-
unit systems), an exhaust termination must be at least 1
ft. (305mm) away from another exhaust termination. An
exhaust termination must also be at least 2 ft. (610 mm)
away from an inside corner. (If the adjacent wall is less than
2 ft. (610 mm) of length, the minimum required distance
away from the inside corner will be equal to the length of
that adjacent wall.)
For multiple-unit, direct-vent sidewall terminations that
combine the intake and exhaust into a single penetration,
space each direct-vent termination at least 1 ft. (305 mm)
away from each other, no matter the orientation. A direct-
vent termination must also be at least 2 ft. (610 mm) away
from an inside corner. (If the adjacent wall is less than 2 ft.
(610 mm) of length, the minimum required distance away
from the inside corner will be equal to the length of that
adjacent wall.)
For direct-vent sidewall
terminationsthatuse two
separate penetrations for
the intake and exhaust,
distance the intake and
exhaust terminations at
least 3 ft. (915 mm) away
from each other, no
matter the orientation.
For multiple-unit rooftop terminations (whether for standard or direct-vent installations) space all
exhaust and intake terminations in accordance with local codes. An exhaust termination must be spaced
from a wall or surface in accordance with local codes as well. In the absence of such a code, an exhaust
termination must be a horizontal distance of at least 2 ft. (610 mm) away from a wall or surface.
Exhaust and/or
direct-vent sidewall
terminations should
be at least 2 ft. (610
mm) away from an
opposite surface/
wall. Do not place
the termination
directly in front of
an opening into a
building.
Please follow all local and national codes in regards to proper termination
clearances. In the absence of such codes, the above clearances can be used as
guidelines. Local codes supersede these guidelines.
CAUTION
A: In accordance with local codes
Air intake
A
Exhaustterminaon
A
A
A
A
Air intake
2.
(610 mm) min
Exhaust
terminaon
3 ft.
(915
mm)
min
Air supply inlet
3 ft. (915 mm)
min
3 ft. (915 mm)
min
Exhaust
termination
Installaon
Installaon Manual
Exhaust
termination
Inside
corner
1 ft.
(305 mm) min
2 ft.
(610 mm) min
1 ft. (305 mm)
min
Combined
intake and
exhaust
termination
Inside
corner
1 ft.
(305 mm) min
2 ft.
(610 mm) min
1 ft. (305 mm)
min
Exhaust
termination
2 ft. (610 mm)
min

18 Page
GAS SUPPLY AND GAS PIPE SIZING
-General-
• The minimum and maximum inlet gas pressures are:
• Inlet gas pressures that fall outside the range of values listed above may adversely affect the
performance of the water heater. These pressures are measured when the water heater is in full
operation.
• Inlet gas pressure must not exceed the above maximum values; gas pressure above the specified range
will cause dangerous operating conditions and damage to the unit.
• Until testing of the main gas line supply pressure is completed, ensure the gas line to the water heater
is disconnected to avoid any damage to the water heater.
-Gas connecons-
1. Install a manual gas shutoff valve between the water heater and the gas supply line.
2. When the gas connections are completed, it is necessary to perform a gas leak test either by applying
soapy water to all gas fittings and observing for bubbles or by using a gas leak detection device.
• The water heater 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 water heater 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).
3. Always purge the gas line of any debris and/or water before connecting to the gas inlet.
Size the gas pipe appropriately to supply the necessary volume of gas required
forthewaterheaterusingANSIZ223.1/NFPA54intheUSAorCAN/CSAB149.1in
Canada or local codes. Otherwise, flow capabilities and output temperatures will
be limited.
NOTICE
Gas type Inlet gas pressure
Natural Gas Min. 5.0” W.C. (1.24 kPa) – Max. 10.5” W.C. (2.61 kPa)
• Check that the type of gas matches the rating plate first.
• Ensure that any and all gas regulators used are operating properly and
providing gas pressures within the specified range shown below. Excess gas
inlet pressure may cause serious accidents.
• Conversion of this unit from natural gas to propane or vice versa will void
all warranty. Contact your local distributor to get the correct unit for your
gas type. The manufacturer is not liable for any property and/or personal
damage resulting from gas conversions.
CAUTION
Installaon
Installaon Manual

19 Page
-Natural Gas Supply Piping-
Maximum delivery capacity of cubic feet of gas per hour of IPS pipe carrying Natural Gas with 0.60 specific gravity
based on pressure drop of 0.5" W.C.
Based on energy content of 1,000 BTU/Cubic ft.: The water heater requires 140 Cubic ft./hr for the 110U (T-KJr2U)
model, 190 Cubic ft./hr for the 310U (T-K4U) model, and 199 Cubic ft./hr for the 510U (T-D2U) model.
Based on Energy Content of 1,000 BTU/Cubic ft:
Divide each appliance's BTU/h requirement by 1,000 BTU/ft3to get the appliances ft3/h requirement.
Take into account the distance the appliance is from the gas meter, look in the above gas chart to properly
size the line.
For sections of the gas line supplying gas to more than one appliance (Ex: Point A to Point B), add up the cubic
ft. per hour requirements of the appliances that are being supplied by that section, and size to the farthest
appliance.
For Example: The section from A to B supplies gas to the furnace, range and dryer. Adding up the BTU/h
requirements and dividing by 1,000 yields a cubic ft. per hour requirement of 220 cubic ft. of gas per hour. The
farthest appliance is the range, which is 50 ft. away from the meter. Looking at the above chart, and under
the column of 50 ft., Section A to B needs to be 1" in order to supply 220 cubic ft.
Water
heater
199,000 BTU/h Dryer
35,000 BTU/h
Gas meter Furnace
120,000 BTU/h
Range
65,000 BTU/h
AB
C
10' Length
1/2" Pipe size
15' Length
1/2" Pipe size
15' Length
1" Pipe size
10' Length
3/4" Pipe size
10' Length
1" Pipe size
5' Length
1-1/4" Pipe size
10' Length
3/4" Pipe size
5' Length
1-1/4" Pipe size
Gas sizing example
(Natural Gas)
Installaon
Installaon Manual
Pipe Size Length
Diameter 10' 20' 30' 40' 50' 60' 70' 80' 90' 100' 125' 150' 200'
3/4" 363 249 200 171 152 138 127 118 111 104 93 84 72
1" 684 470 377 323 286 259 239 222 208 197 174 158 135
1 1/4" 1,404 965 775 663 588 532 490 456 428 404 358 324 278
1 1/2" 2,103 1,445 1,161 993 880 798 734 683 641 605 536 486 416
2" 4,050 2,784 2,235 1,913 1,696 1,536 1,413 1,315 1,234 1,165 1,033 936 801
Unit: Cubic feet per hour

20 Page
-Measuring inlet gas pressure-
The water heater cannot perform properly without sufficient inlet gas pressure. Below are instructions on
how to check the inlet gas pressure. THIS IS ONLY TO BE DONE BY A LICENSED PROFESSIONAL.
WATER CONNECTIONS
All pipes, pipe fittings, valves and other components, including soldering materials, must be suitable for
potable water systems.
1. A manual shutoff valve must be installed on the cold water inlet to the water heater between the main
water supply line and the water heater.
2. In addition, a manual shutoff valve is also recommended on the hot water outlet of the unit. If the
water heater is installed within, or subjected to, a closed loop water system, a thermal expansion tank
or code approved device to handle thermal expansion must be installed.
1. Turn off all electric power to the water heater if service is to be performed.
2. Turn the manual gas valve located on the outside of the unit clockwise to the
off position.
• Do not use this water heater if any part has been submersed under water.
Immediately call a licensed professional to inspect the water heater to replace
any damaged parts.
• Do not reverse the hot outlet and cold inlet connections to the water heater.
This will not properly activate the water heater.
CAUTION
1. Shut off the manual gas valve on the gas supply line.
2. Remove the screw for the pressure port located on the gas
inlet of the water heater shown in the diagram on the right.
3. Connect the manometer to the pressure port.
4. Re-open the manual gas valve. Check to see that there
are no gas leaks. Open some of the fixtures that use the
highest flow rate to turn on the water heater.
5. Check the inlet gas pressure. When the water heater is on
maximum and minimum burn, the manometer should read
from 5.0” to 10.5” W.C. (1.24 to 2.61 kPa) for Natural gas.
3. Before installing the water heater, flush
the water line to remove all debris, and
after installation is complete, purge
the air from the line. Failure to do so
may cause damage to the heater.
4. There is a wire mesh filter within
the cold inlet to trap debris from
entering your heater. This will need
to be cleaned periodically to maintain
optimum flow. (Refer to p. 41.)
Pressure port
Cold
inlet
Hot
outlet
Gas
inlet
As Close as
Possible
Pressure relief valve
Installaon
Installaon Manual