Takagi T-K3 User manual

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T-K3 / T-K3-Pro
On-Demand Water Heater
Installation Manual and Owner’s Guide
FEATURING
•ENDLESS HOT WATER
•ON DEMAND USAGE
•COMPACT, SPACE SAVING
•ENERGY CONSERVATION
•COMPUTERIZED SAFETY
•NO PILOT LIGHT
•EASY LINK SYSTEM
WARNING
This product must be installed and
serviced by a licensed plumber, a
licensed gas fitter, or a professional
service technician. Improper installation
and/or operation, or installation by an
unqualified person, will void the
warranty.
WARNING
If the information in this manual is not
followed exactly, a fire or explosion may
result, causing property damage,
personal injury, or death.
TAKAGI Indust
r
ial Co. US
A
, Inc.
5 Whatney
Irvine, CA 92618
Toll Free: [phone] USA
Toll Free: [phone] CANADA
Flash Water Heater™
Model T-K3 and T-K3-Pro
Suitable for potable water heating and space heating

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CONTENTS
*40 psi or above is recommended for maximum flow
NOTE
*Check the rating plate to ensure this product
matches your specifications.
*In accordance with ANSI Z21.10.3 and
SCAQMD Rule 1146.2, CO emission does not
exceed 400 PPM for normal input
SPECIFICATIONS
T-K3 and T-K3-Pro
Natural Gas Input
(Operating Range) Min: 11,000 Btu/h Max: 199,000 Btu/h
LPG Input
(Operating Range) Min: 11,000 Btu/h Max: 199,000 Btu/h
Gas Connection ¾” NTP
Water Connections ¾” NTP
Water Pressure 15 - 150 psi*
Natural Gas Pressure
Inlet Min. 5.0” WC
Max. 10.5” WC
LP Gas
Pressure Inlet Min. 8.0” WC Max. 14.0” WC
Manifold Pressure Natural: 2.5” WC
Propane: 4.4” WC
Weight 40 lbs.
Dimensions H20.5” x W13.8” x D8.5”
Ignition Electric Ignition
Supply 120VAC (60Hz)
Operation 92 W
(0.77A)
Standby 6.2 W
(0.05A)
Electric Consumption
Freeze-
Protection 111 W
(0.93A)
SPECIFICATIONS……………………...
INTRODUCTION…………………….…
SAFETY GUIDELINES…………….…..
INSTALLATION……………………..….
General…………………………….…
Included Accessories……………….
Outdoor Installation………………….
Indoor Installation…………………....
Direct Intake Vent System………….
Venting Instructions………………....
Gas Supply / Gas Pipe Sizing…...…
Water Connections……………..……
Pressure Relief Valve…………….…
Electrical Connections……………....
Remote Controller Connection…..…
Easy Link System………..………..…
Pump Connection………………..…..
Initial Operation………………………
NORMAL OPERATION…………..……
Normal Operation…………………...
Flow………………………………...…
Freeze Protection System …………
Temperature Settings ………………
Maintenance and Service…………..
GENERAL TROUBLESHOOTING……
WIRING DIAGRAM…………………….
OPERATING SAFETY…………………
APPLICATIONS...………………………
Space Heating……….………………
Re-Circulation………….…………….
Dual-Purpose Heating………………
OPTIONAL ITEMS……………………..
COMPONENTS DIAGRAM……………
PARTS LIST…………………………….
OUTPUT TEMPERATURE CHART….
WARRANTY………….………………....
2
3
4
5
6
6
8
9
10
11
17
19
20
21
22
23
26
27
28
28
29
29
30
31
32
35
36
38
38
38
39
40
41
44
46
47
Takagi reserves the right to discontinue, or change at any time, specifications
or designs without notice and without incurring obligations.

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INTRODUCTION
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 automatically ignites the burner.
5. Water circulates through the heat exchanger and then gets hot.
6. The computer will modulate the gas supply valve and water flow to produce the right
amount of hot water at the correct temperature.
7. When the tap is turned off, the unit shuts down.
*This diagram illustrates
Takagi’s tankless water
heater design concepts
only and is not accurate to
the T-K3/T-K3-Pro’s
physical description.
•This manual provides information necessary for the installation, operation, and
maintenance of the Flash T-K3
/
T-K3-Pro water heater.
•The model description is listed on the rating plate which is attached to the front cover 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 with Takagi or its
local re
p
resentative.
•The T-K3/T-K3-Pro Water Heater is an on-demand, tankless water heater designed to
efficientl
y
su
pp
l
y
endless hot water for
y
our needs.
•The principle behind the T-K3/T-K3-Pro Water Heater is simple:

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SAFETY GUIDELINES
•Installation and service must be performed by a qualified installer (for
example, a licensed plumber or gas fitter), otherwise the warranty by Takagi
will be void.
•The installer (licensed professional) is responsible for the correct
installation of your Flash T-K3/T-K3-Pro Water Heater and for compliance
with all national, state/provincial, and local codes.
PLEASE READ THIS MANUAL CAREFULLY AND FOLLOW ALL DIRECTIONS.
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, Propane 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 Canada Electrical Code Part 1 in Canada.
3. Carefully plan where you intend to install your T-K3/T-K3-Pro 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. 5).
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 Takagi.
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 125ºF can cause severe burns instantly or death from
scalding. The water temperature is set at 122ºF (50ºC) 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. 19 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 Prevention 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 Prevention System on p. 29 for more information.
RATING
PLATE
Prohibited
WARNING

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INSTALLATION
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 at the
beginning of this manual.
•The warranty will not cover damage caused by water quality. Water
hardness that leads to scale formation and/or corrosion may
affect/damage the water heater. Hard water scaling and/or corrosion must
be avoided or controlled by proper water treatment.
•TAKAGI recommends using the Takagi 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 T-K3/T-K3-Pro is designed to operate with minimal sound,
TAKAGI 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. Takagi 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.
•TAKAGI does not recommend installing unit in an attic due to safety
issues. If you install your T-K3/T-K3-Pro in an attic:
•Make sure your unit will have enough combustion air and proper
ventilation.
•Keep the area around your T-K3/T-K3-Pro clean. When dust collects on
the flame sensor, the water heater will shut down on errors.
•If the above conditions cannot be met, use the direct vent conversion kit
TK-TV10.
•Locate unit for easy access for service and maintenance.
•A drain pan is required to be installed under the water heater in case of
leaks.
CAUTION
WARNING

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GENERAL
1. The manifold gas pressure is preset at the factory. It is computer controlled and should
not need adjustment.
2. Maintain proper space for servicing. Install the unit so that it can be connected or
removed easily. Refer to p. 7, p.8 and p. 9 for proper clearances.
3. The electrical connection requires a means of disconnection, to terminate power to the
water heater for servicing and safety purposes.
4. If you will be installing the unit in a contaminated area with a high level of dust, sand,
flour, aerosols or other contaminants/chemicals, they can become airborne and enter
and build up within the fan and burner causing damage to the unit. In those
environments (e.g. residential or commercial laundry facilities, hair salons, pet salons,
chemical plants etc.), please purchase the optional TK-TV10 direct vent conversion kit
and convert the T-K3/T-K3-Pro to a sealed combustion unit. Direct venting allows the T-
K3/T-K3-Pro to draw fresh intake air from the outside. The warranty will not cover
damage caused to the unit due to installation in a contaminated environment that has
not been converted using the TK-TV10.
5. Particles from flour, aerosols, and other contaminants may clog the air vent or reduce
the functions of the rotating fan and cause improper burning of the gas. Regularly ensure
that the area around the unit is dust- or debris-free; regular maintenance is
recommended for these types of environment.
6. 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).
INCLUDED ACCESSORIES
Check that the installation manual, the communication cable, and the warranty card are
included with the unit.
Items
Manual
Communication Cable
Warranty Card
Qt
y
: 1
Qty: 1
Qty: 1

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WARNING FOR INSTALLATION LOCATIONS
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 feet from its top or
eaves. The area under an overhang must be
open to three sides.
Do not install the water heater vent terminator
within 1 ft. in the USA of any air intake or
building opening, and with in 3 ft. in Canada
of any air intake or building opening. (Refer to
p.14)
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
3 Ft.

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The dark square is the direction
the dipswitch should be set to.
Keep the clearances.
OUTDOOR INSTALLATION
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, Propane Installation Code in Canada.
2. Install outdoors only in areas with mild, temperate climates.
3. Ensure that the unit is set for outdoor installation. Locate the bank of dipswitches to the
right of the 7-Seg. LED on the computer board. The ‘OUT’ dipswitch on the computer
board should be switched to its ‘ON’ (up) position (Do not adjust the bank of dipswitches
above the LED’s).
4. The outdoor vent cap must be used when unit is installed outdoor. Takagi requires the
use of its part No. TK-TV04.
5. When installed outdoors, the T-K3/T-K3-Pro water heater shall be wall-mounted or
mounted on a stand. Locate the water heater in an open, unroofed area and maintain
the following minimum clearances:
ING
Make sure power to the unit is
turned OFF before changing
the dipswitch settings.
There is a 2” clearance from the left
and right sides of the unit to
combustible and non-combustible
surfaces. However, if any portion or
area of the surface is exposed to the
exhaust fumes (i.e. directly to the sides
of the vent cap), that surface must be
at least 24” away.
*Side 24”
*Side 24”
Right Bank of Dipswitches
7-Seg LED
Right bank of
dipswitches
Left bank of
dipswitches
Top 36”
Back 1”
Front 24”
Bottom 12”
Side 2”
Side 2”

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Keep the clearances.
INDOOR INSTALLATION
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, Propane
Installation Code in Canada.
2. When installed indoors, the T-K3/T-K3-Pro water
heater shall be located in an area to maintain the
following minimum clearances around the unit:
Combustion Air Supply
The water heater location must provide enough air for proper combustion and ventilation of the
surrounding area. See the latest edition of ANSI Standard Z223.1 or any applicable local codes.
In general, these requirements specify that if the unit is installed in a confined space, there must
be a permanent air supply opening.
Minimum recommended air supply opening size for water heater:
Water heater size
When drawing make-up air from
outside the building
When drawing make-up air from inside
the building (from other rooms within)
13.3 Sq. IN 199 Sq. IN
MAX 199,000 BTU
When combustion air is supplied
from outside the building, an
opening communicating directly
with the outside should have a
minimum free area of one
square inch per 15,000 BTUH
input of the total input rating of
water heater in the enclosed
area.
When combustion air is supplied from
inside the building, an opening
communicating with the rest of the
dwelling should have a minimum free
area of one square inch per 1,000
BTUH input of the total input rating of
water heater in the enclosed area.
This opening should never be less
than 199 sq. in.
Combustible Air Supplied by Mechanical fan or Make up air device
The T-K3/T-K3-Pro water heater is equipped with a combustible air sensor that will shut off the
unit when inadequate combustible air supply to unit is detected.
•If a mechanical fan or make up air device is used to supply air to the water heater or
utility room, the installer should make sure it does not create drafts which could cause
nuisance shutdowns.
•If a blower is necessary to provide adequate combustion air to the water heater, the
blower and water heater must be set up so that the water heater cannot fire unless the
blower is operating. Possible methods include the use of external flow
sensors/transmitters and relays.
Bottom 12”
Side 2”
Side 2”
Back 1”
Top 12”
Front 4”
(24” Recommended
for Maintenance)

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The dark square is the direction
the dipswitch should be set to.
DIRECT INTAKE VENT SYSTEM
This T-K3/T-K3-Pro water heater may be converted to a direct vent (sealed combustion)
appliance by installing an adapter (Part No. TK-TV10) which will bring all required combustible
air from outside the building. When installing the TK-TV10 conversion kit, please follow all
instructions included with the kit.
•The T-K3/T-K3-Pro must be installed in a location where the proper amount of
combustible air will be available to it at all times without obstructions.
•If used as a direct vent appliance, the T-K3/T-K3-Pro requires a 3” combustible air
supply pipe. The intake pipe must be sealed airtight.
•Air supply pipe can be made of ABS, PVC, galvanized steel, corrugated aluminum,
corrugated stainless steel or Category III stainless steel.
•Change the dipswitch settings to the direct vent system. (See diagram below)
•Sidewall venting is recommended for the direct vent system.
•Takagi recommends running the exhaust vent and the intake pipe parallel.
Make sure power to the unit is
turned OFF before changing
the dipswitch settings.
7-Seg LED
Right bank of
dipswitches
Left bank of
dipswitches
TK-TV10 Direct Vent
Conversion Kit
INLET EXHAUST
T
K
-T
V
10
DIRECT VENT
CONVERSION KIT
Right Bank of Dipswitches

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VENTING INSTRUCTIONS
WARNING: Improper venting of this appliance can result in excessive levels of
carbon monoxide which can result in severe personal injury or death.
This water heater must be vented in accordance with the section “Venting of Equipment" of the
latest edition of the Natural Fuel Gas Code: The ANSI Z223.1, All applicable local building
codes, Section 7 of the CAN/CSA B149.1 Natural Gas in Canada, Propane Installation Code in
Canada.
EXHAUST VENT
This is a Category III appliance and must be vented accordingly. The vent system must be
sealed air tight. 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
350ºF. For best results, a vent system should be as short and straight as possible.
1. This Takagi water heater is a Category III appliance and must be vented accordingly with
any 4” vent approved for use with Category III or Special BH type gas vent.
2. TAKAGI recommends the “T-Vent” line manufactured by TAKAGI (Refer to Takagi’s
“T-Vent” brochure for details). However, the following are also UL listed manufacturers:
ProTech Systems Inc. (FasNSeal), Flex-L Inc., Z-Flex Inc. (Z-Vent III), Metal-Fab Inc., and
Heat-Fab Inc. (Saf-T Vent).
3. Follow the vent pipe manufacturer’s instructions when installing the vent pipe.
4. 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).
5. The maximum length of exhaust vent piping must not exceed 50 ft. deducting 5 ft. for each
elbow used in the venting system. Do not use more than 5 elbows.
Diameter Max. No. of Elbow Max. Vertical or Horizontal run in Length
4” 5 Ea. 50 ft.
*For each elbow added, deduct 5 ft. from max. Vent length.
No. of Elbows Max. Vertical or Horizontal Length
0 50 ft.
1 45 ft.
2 40 ft.
5 25 ft.
6. When the horizontal vent run exceeds 5 ft., support the vent run at 3 ft. intervals with
overhead hangars.
7. Takagi will not be responsible for any damage to the water heater caused by condensation
from the vent. Installing a condensate drip is recommended. Please refer to p. 13 for the
diagrams.
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.

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VENT TERMINATION
WARNING: Improper installation can cause nausea or asphyxiation, severe injury
or death from carbon monoxide and flue gases poisoning. Improper installation
will void product warranty.
•The vent terminator provides a means of installing vent pipe through the building wall and
must be located in accordance with ANSI Z223.1/NFPA 54, or in Canada with CAN/CSA-
B149.1 and local applicable codes.
•A proper sidewall vent terminator is recommended when the water heater is vented through
a sidewall. If the T-K3/T-K3-Pro is converted to a direct-vent unit, a proper sidewall direct-
vent terminator is to be used.
General rules for venting the T-K3/T-K3-Pro water heater are:
1. Place the water heater as close as possible to the vent terminator.
2. The vent collar of the water heater must be fastened directly to an unobstructed vent pipe.
3. Do not weld the vent pipe to the water heater collar.
4. Do not cut the vent collar of the unit.
5. The weight of the vent stack must not rest on the water heater.
6. The vent must be easily removable from the top of the water heater for normal service and
inspection of the unit.
7. The water heater vent must not be connected to any other gas appliance or vent stack.
8. Avoid locating the water heater vent terminator 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.
9. Avoid using an oversized vent pipe or using extremely long runs of the pipe.
10. Locate the vent terminator so that it cannot be blocked by any debris, at any time. Most
codes require that the terminator be at least 12 inches above grade, but the installer may
determine if it should be higher depending on the job site condition and applicable codes.
11. For rooftop venting, a rain cap must be installed.
12. TAKAGI recommends the “T-Vent” line manufactured by TAKAGI (Refer to Takagi’s
“T-Vent” brochure for details). However, the following are also UL listed manufacturers:
ProTech Systems Inc. (FasNSeal), Flex-L Inc., Z-Flex Inc. (Z-Vent III), Metal-Fab Inc., and
Heat-Fab Inc. (Saf-T Vent).

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Horizontal Installation Diagram
Vertical Installation Diagram
•Regarding the clearance from the terminator to the air inlet or opening, refer to the next
page.
•Install a condensation drain in the venting.
•Follow the vent system to vent manufacturer’s instruction and local code.
•Do not common vent or connect any vent from other appliances to the T-K3/T-K3-Pro vent.
•Use 4” category III approved or Special BH, single or double wall stainless steel vent pipe.
Wall
Roof
Rain Cap
Roof Flashing
Sidewall
Vent
Terminator
Vertical Condensation Drain
(Install according to local codes)
TK-BF01 Backflow Preventor
(Recommended for freezing
weather conditions: 36°F and
below)
TK-BF01 Backflow preventor
(Recommended for freezing
weather conditions: 36°F and
below)
Vertical Condensation Drain
(Install according to local codes)

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VENT CLEARANCES
Canada U.S.A
Direct vent and
other than Direct
Vent Direct vent Other than Direct Vent
A Clearance 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.
C Clearance 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. * * *
E Clearance to unventilated soffit * * *
F Clearance to outside corner * * *
G Clearance to inside corner * * *
H Clearance to each side of center line
extended above meter/regulator assembly 3 feet * *
I Clearance 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.
K Clearance to mechanical air supply inlet. 6 feet 3 feet 3 feet
L Clearance above paved sidewalk or
paved driveway located on public
property. 7 feet * 7 feet
M Clearance 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 requirement of the gas supplier.

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ADDITIONAL CLEARANCES
Please follow all local and national codes in regards to proper termination clearances. In the
absence of such codes, the following clearances can be used as guidelines. Local codes
supersede these guidelines.
For sidewall terminations
Exhaust termination
1ft.
1ft. 2ft.
Inside
corner
Air supply inlet
3ft.
3ft.
3ft.
Direct vent
termination
1ft.
1ft.
Inside
corner
2ft.
For multiple sidewall exhaust terminations (e.g.
multi-unit systems), an exhaust termination must
be at least 1 ft. away from another exhaust
termination. An exhaust termination must also be
at least 2 ft. away from an inside corner (if the
adjacent wall is less than 2 ft. of length, the
minimum required distance away from the inside
corner will be equal to the length of the wall).
For direct-vent sidewall terminations that use two
separate penetrations for the intake and exhaust,
distance the intake and exhaust terminations at
least 3 ft. away from each other, no matter the
orientation.
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. away from each other, no matter the
orientation. A direct-vent termination must also be
at least 2 ft. away from an inside corner (if the
adjacent wall is less than 2 ft. of length, the
minimum required distance away from the inside
corner will be equal to the length of the wall).

- 16 -
For rooftop terminations
A
A
2ft.
Exhaust
termination
A
ir intake
A
A
A
A
ir intake
Exhaust
termination
For multiple-unit rooftop terminations (whether for standard indoor 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. away from a wall or surface.
2ft. Exhaust
termination
Exhaust and/or direct-vent
sidewall terminations should be at
least 2 ft. awayfrom an opposite
surface/wall. Do not place the
termination directly in front of an
opening into a building.
A: in accordance with local codes

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GAS SUPPLY AND GAS PIPE SIZING
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 3to the off position.
WARNING: Conversion of this unit from natural gas to propane or vise versa
cannot be done in the field. Contact your local distributor to get the correct unit for
your gas type. Conversion done by anyone other than the manufacturer will void all
warranty. Takagi is not liable for any property and/or personal damage
resulting from unauthorized conversions.
*Check that the type of gas matches the rating plate first.
1. The minimum and maximum inlet gas pressures are:
Natural Gas Min. 5.0” WC - Max. 10.5” WC
Propane Gas Min. 8.0” WC - Max. 14.0” WC
2. Gas pressure below this specified range for the T-K3/T-K3-Pro and/or insufficient gas volume will
adversely affect performance. These pressures are measured when the T-K3/T-K3-Pro is in full
operation.
3. 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. Ensure that any and all
gas regulators used are operating properly and are providing gas pressures within the specified
range shown above.
4. Until testing of the main gas line supply pressure is completed, ensure the gas line to the T-K3/T-
K3-Pro is disconnected to avoid any damage to the water heater.
MEASURING INLET GAS PRESSURE
The T-K3/T-K3-Pro 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.
1. Shut off the manual gas valve on the supply gas line.
2. Open a faucet. The unit should turn on and the gas in the
gas pipe line should purge. Leave the faucet on to keep the
unit running until the unit shut down due to lack of gas
supply. Then shut the faucet off.
3. Remove the screw for the pressure port located on the gas
inlet of the T-K3/T-K3-Pro shown in the diagram to the right.
4. Connect the manometer to the pressure port.
5. Re-open the manual gas valve. Check to see that there are
no gas leaks.
6. Open some of the fixtures that use the highest flow rate to
turn on the T-K3/T-K3-Pro.
7. Check the inlet gas pressure. When T-K3/T-K3-Pro is on a
maximum burn, the manometer should read from 5.0” to
10.5” WC for Natural gas, from 8.0” to 14.0” WC for Liquid Propane.
TO TURN OFF GAS TO APPLIANCE

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Size the gas pipe appropriately to supply the necessary volume of gas required
for the T-K3/T-K3-Pro (199,000 BTUH for both Natural Gas and Liquid Propane)
using ANSI233.1/NAPA 54 in the USA or CAN/CSA B149.1 in Canada or local
codes. Otherwise, flow capabilities and output temperatures will be limited.
1. Install a manual gas shut-off valve between the T-K3/T-K3-Pro 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.
3. Always purge the gas line of any debris and/or water before connecting to the gas inlet.
Natural Gas Supply Piping
Maximum Delivery Capacity of Cubic Feet of Gas per Hour of IPS Pipe Carrying Natural Gas of 0.60 Specific Gravity
Based on Pressure Drop of 0.5” WC
Based on Energy Content of 1000 BTU/Cubic Ft.: T-K3/T-K3-Pro requires 199 Cubic Ft./hr.
Unit: Cubic Feet per Hour
Pipe Size Length in Feet
inches 10’ 20’ 30’ 40’ 50’ 60’ 70’ 80’ 90’ 100’ 125’ 150’ 200’
¾” 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 ¼” 1404 965 775 663 588 532 490 456 428 404 358 324 278
1 ½” 2103 1445 1161 993 880 798 734 683 641 605 536 486 416
2” 4050 2784 2235 1913 1696 1536 1413 1315 1234 1165 1033 936 801
Propane (LP) Gas Supply Piping
Maximum Capacity of Propane (LP) Gas Based on 11” WC supply pressure at a 1.0” WC pressure drop Unit: kBTU per Hour
Pipe Size Length in Feet
inches 10’ 20’ 30’ 40’ 50’ 60’ 70’ 80’ 90’ 100’ 125’ 150’ 200’
¾” 567 393 315 267 237 217 196 185 173 162 146 132 112
1” 1071 732 590 504 448 409 378 346 322 307 275 252 213
1 ¼” 2205 1496 1212 1039 913 834 771 724 677 630 567 511 440
1 ½” 3307 2299 1858 1559 1417 1275 1181 1086 1023 976 866 787 675
2” 6221 4331 3465 2992 2646 2394 2205 2047 1921 1811 1606 1496 1260
Based on Energy Content of 1000BTU/Cubic Ft:
Divide each appliance’s BTU requirement by 1000BTU to get
the appliances Cubic Ft. requirement.
Takagi 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.
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 requirements and
dividing by 1000 yields a cubic ft. requirement of 220 cubic ft. of
gas. The farthest appliance is the range, which is 50 ft. away
from the meter. Looking at the above chart, and under the
column of 50ft., Section A to B needs to be 1” in order to supply
220 cubic ft.
C
10’ Length
3/4” Pipe Size
Gas Sizing Example
(Natural Gas)
15’ Length
1/2” Pipe Size
10’ Length
1/2” Pipe Size
Furnace
120,000BTU
10’ Length
1” Pipe Size
T-K3/
T-K3-Pro
199,000BTU
5’ Length
1-1/4” Pipe Size
Range
65,000BTU
10’ Length
3/4” Pipe Size
Dryer
35,000BTU
15’ Length
1” Pipe Size
5’ Length
1-1/4” Pipe Size
Gas Meter
B
A

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WATER CONNECTIONS
Do not use this water heater if any part has been submersed under water.
Immediately call a licensed professional to inspect the water heater and to replace
any damaged parts.
1. All pipes, pipe fittings, valves and other components, including soldering materials, must
be suitable for potable water systems.
2. A manual shut off valve must be installed on the cold water inlet to the water heater
between the main water supply line and the T-K3/T-K3-Pro.
3. In addition, a manual shut off valve is also recommended on the hot water outlet of the
unit. If the T-K3/T-K3-Pro is installed within, or subjected to, a closed loop water system, a
thermal expansion tank must be installed.
4. 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.
5. 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.
CAUTION: Do not reverse the hot outlet and cold inlet connections to the
T-K3/T-K3-Pro Water Heater. This will not properly activate the water
heater.
FOR YOUR SAFETY, READ BEFORE OPERATING:

- 20 -
PRESSURE RELIEF VALVE
The Flash T-K3/T-K3-Pro has a high-temperature shut off switch built in as a standard safety
feature (called a Hi-Limit switch) therefore a “pressure only” relief valve is required.
1. This unit does not come with an approved pressure relief valve.
2. An approved pressure relief valve must be installed on the hot water outlet.
3. The pressure relief valve must conform to ANSI Z21.22 or CAN 1-4.4 and installation must
follow local code.
4. The discharge capacity must be at least 199,000 BTU/hr.
5. The pressure relief valve needs to be rated for a maximum of 150 psi.
6. The discharge piping for the pressure relief valve must be directed so that the hot water
cannot splash on anyone or on nearby equipment.
7. Attach the discharge tube to the pressure relief valve and run the end of the tube to within
6" from the floor. This discharge tube must allow free and complete drainage without any
restrictions.
8. If the pressure relief valve installed on the T-K3/T-K3-Pro discharges periodically, this may
be due to a defective thermal expansion tank or defective pressure relief valve.
9. The pressure relief valve must be manually operated periodically to check for correct
operation.
Hot outlet Cold inlet Gas
Pressure Relief
Valve
As Close as
Possible