Takagi T-K3-SP User manual

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T-K3-OS and T-K3-SP
Instantaneous 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
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 Industrial Co. USA Inc.
5 Whatney
Irvine, CA 92618
Toll Free: [phone] USA
Toll Free: [phone] CANADA
Flash Water Heater™
Model T-K3-OS
Suitable for potable water heating and space heating
Flash Water Heater™
Model T-K3-SP

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-In accordance with ANSI Z21.10.3 and SCAQMD
Rule 1146.2, CO emission does not exceed 400 PPM
for normal input.
CONTENTS
*50 psi or above is recommended for maximum flow
NOTE
-Check the rating plate to ensure this product
matches your specifications.
SPECIFICATION
T-K3-OS and T-K3-SP
Natural Gas Input
(Operating Range) Min: 11,000 Btu/h Max: 190,000 Btu/h
LPG Input
(Operating Range) Min: 11,000 Btu/h Max: 190,000 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. 13.5” WC
Manifold Pressure of
the T-K3-OS Natural: 2.8” WC
Propane: 3.1” WC
Manifold Pressure of
the T-K3-SP Natural: 2.4” WC
Propane: 4.1” WC
Weight 40 lbs.
Dimensions H20.5” x W13.8” x D8.5”
Ignition Electric Ignition
Supply 120VAC (60Hz)
Operation 92 W
Standby 6.2 W
Consumption
of the T-K3-
OS Freeze-
Protection 111 W
Operation 92 W
Standby 6.2 W
Electric
Consumption
of the T-K3-
SP Freeze-
Protection 111 W
SPECIFICATIONS……………………...
INTRODUCTION…………………….…
SAFETY GUIDELINES…………….…..
INSTALLATION……………………..….
General…………………………….…
Accessories…………………………..
Outdoor Installation………………….
Indoor Installation…………………....
Venting Instructions (T-K3-SP ONLY) …
Gas Supply / Gas Pipe Sizing…...…
Water Connections……………..……
Pressure Relief Valve…………….…
Electrical Connections……………....
Remote Controller Connection…..…
Initial Operation………………………
NORMAL OPERATION…………..……
Normal Operation…………………...
Flow………………………………...…
Freeze Protection System …………
Temperature Setting ………………..
Maintenance and Service…………..
TROUBLESHOOTING…………………
WIRING DIAGRAM…………………….
OPERATING SAFETY…………………
APPLICATIONS………………………..
Space Heating……………………….
Dual-Purpose Heating………………
Re-Circulation ……………………….
OPTIONAL ITEMS……………………..
COMPONENTS DIAGRAM &
PARTS LIST……….
OUTPUT TEMPERATURE CHART….
WARRANTY ……………………………
2
3
4
5
6
6
7
9
10
14
16
17
18
18
19
20
20
21
21
22
23
24
27
28
30
30
31
32
33
34
38
39
Manufacturer reserves the right to discontinue, or change at any time, specifications or
designs without notice and without incurring obligations.

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INTRODUCTION
•This manual provides information necessary for the installation, operation, and
maintenance of the Model T-K3-OS/SP 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 representative.
•The T-K3-OS/SP Water Heater is an instantaneous, tankless water heater designed to
efficiently supply endless hot water for your needs.
•The principle behind the T-K3-OS/SP Water Heater is simple:
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 is to illustrate Takagi’s tankless water
heater design concepts only and may not be accurate
to the T-K3-OS/SP’s physical description.

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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-OS/SP Water Heater and for compliance with
all national, state/provincial, and local codes.
*For all units installed in the state of Massachusetts, it is required that the installer
either be a licensed plumber or licensed gas fitter.
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-OS/SP 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. 16 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. 21 for more information.
Prohibited
WARNING
RATING PLATE

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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 T-K3-OS must be installed OUTDOORS ONLY. DO NOT install the
T-K3-OS indoors. The T-K3-SP can be installed either indoors or outdoors.
•The warranty will not cover damage caused by water quality. Water
hardness may affect the water heater. Water heater may be damaged.
•The water heater must be installed vertically.
•If the T-K3-SP is installed in a beauty salon, some chemicals used in a
beauty salon may affect the flame sensor. Water heater may not work
properly. TAKAGI recommends isolating the T-K3-SP from beauty
salon elements.
•Although the T-K3-OS/SP 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. If there is no
drain, 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-SP in an attic:
•Make sure your unit will have enough combustion air and proper
ventilation.
•Keep the area around your T-K3-SP clean. When dust collects on the
flame sensor, the water heater will shut down on errors.
•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 and p. 9 for proper clearances.
3. The electrical connection requires a means for switching off the power supply.
4. If you will be installing the unit in a contaminated area with a high level of dust, sand,
flour, aerosols or other contaminants, they can become airborne and enter and build up
within the fan and burner causing damage to the unit. Particles from flour, aerosols, and
other contaminants may 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.
5. Do not install the unit where the exhaust vent/opening is pointing into any opening in a
building or where the noise may disturb your neighbors. Make sure the vent
termination/exhaust opening meets the required distance by local code from any
doorway or opening to prevent exhaust from entering a building (refer to p. 13).
ACCESSORIES
Check that the installation manual and the warranty card are included with the unit.

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The dark square is the direction
the dipswitch should be set to.
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. Outdoor installation for mild climates only.
3. When installing the T-K3-SP outdoors, ensure that the T-K3-SP is set for outdoor
installation. Locate the bank of dipswitches at the bottom-right corner of the computer
board. The ‘OUT’ dipswitch on the computer board should be switched to ‘ON’ (up).
For the T-K3-OS, no dipswitches need to be changed.
4. The outdoor vent cap must be used when the T-K3-SP is installed outdoor. Takagi
requires the use of its part No. TK-TV04.
5. When installed outdoors, the T-K3-OS/SP water heater shall be wall mounted only.
Locate the water heater in an open, unroofed area and maintain the following minimum
clearances:
Make sure power to the unit is
turned OFF before changing
the dipswitch settings.
The dipswitch setting, as shown to
the right, is for the T-K3-SP ONLY.
OS SP

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WARNING
Do not install the heater where water, debris
or flammable vapors may get into the flue
terminal/opening. This may cause damage to
the heater and void the warranty.
Do not have the vent terminal/opening
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.13).
Avoid locating the water heater exhaust
opening 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.
Prohibited Prohibited
Prohibited
T-K3-OS
T-K3-SP

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INDOOR INSTALLATION (T-K3-SP ONLY)
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-
SP 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 the T-K3-SP:
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)
12.7 Sq. IN 190 Sq. IN
MAX 190,000 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 190 sq. in.
Combustible Air Supplied by Mechanical fan or Make up air device
The T-K3-SP 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.
SP

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VENTING INSTRUCTIONS (T-K3-SP ONLY)
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 (T-K3-SP ONLY)
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. The T-K3-SP 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. The following are 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. For horizontal runs, slope the vent run downwards toward the vent terminal
at a rate of ¼” per foot. For horizontal runs that do not slope downward and for vertical
runs, installing a condensate drip is recommended. Please refer to p. 12 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 (T-K3-SP ONLY)
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.
•The sidewall vent terminator, TK-TV01, is recommended when the water heater is vented
through a sidewall.
General rules for venting the T-K3-SP 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.

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•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-SP vent.
•Use 4” category III approved or Special BH, single or double wall stainless steel vent
pipe.

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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.
*Outdoor installation is considered as direct vent.

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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. 13.5” WC
2. Gas pressure below this specified range for the T-K3-OS/SP and/or insufficient gas volume
will adversely affect performance.
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.
4. Until testing of the main gas line supply pressure is completed, ensure the gas line to the
T-K3-OS/SP is disconnected to avoid any damage to the water heater.
MEASURING INLET GAS PRESSURE
The T-K3-OS/SP 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-OS/SP 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-OS/SP.
7. Check the inlet gas pressure. When T-K3-OS/SP is on a
maximum burn, the manometer should read from 5.0” to
10.5” WC for Natural gas, from 8.0” to 13.5” 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-OS/SP (190,000 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-OS/SP 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 before connecting to the heater 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 1100 BTU/Cubic Ft.: T-K3-OS/SP requires 173 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

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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-OS/SP.
3. In addition, a manual shut off valve is also recommended on the hot water outlet of the
unit. If the T-K3-OS/SP 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-OS/SP Water Heater. This will not properly activate the water heater.
FOR YOUR SAFETY, READ BEFORE OPERATING:

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PRESSURE RELIEF VALVE
The FLASH T-K3-OS/SP 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 190,000 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-OS/SP 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.

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Remote controller terminal
on the computer board
When wiring the remote to the
computer board, please put the
wires through the hole on the
bottom of the unit’s casing
ELECTRICAL CONNECTIONS
WARNING: Follow the electrical code requirements of the local authority having
jurisdiction. In the absence of such requirements, follow the latest edition of the
National Electrical Code ANSI/NFPA 70 in the U.S. or the latest edition of CSA
C22.1 Canadian Electrical Code, Part 1, in Canada.
CAUTION: When servicing or replacing parts within the T-K3-OS/SP, label all wires
prior to disconnection to facilitate an easy and error-free reconnection. Wiring errors
can cause improper and dangerous operation. Verify proper operation after
servicing.
1. The heater must be electrically grounded. Do not
attach the ground wire to either the gas or the
water piping.
2. The FLASH T-K3-OS/SP water heater requires
AC 120V 60 Hz electrical power supply that is
properly grounded.
•An on/off switch controlling the main power to
the T-K3-OS/SP must be provided for service
reasons;
•Connect the power supply to the T-K3-OS/SP
exactly as shown in the wiring diagram;
3. A green screw is provided in the junction box to
ground the connection.
4. Can be hardwired or wired to a plug-in.
5. The use of a surge protector is recommended in
order to protect the unit from power surges.
REMOTE CONTROLLER CONNECTION
•Minimum 18AWG wire (No polarity)
•Maximum 150 feet long
TK-RE02 (Optional)
・Please follow the TK-RE02’s manual.

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INITIAL OPERATION
•Check the GAS and WATER CONNECTIONS for leaks before firing it for the first time.
•Open the main gas supply valve to the unit using only your hand to avoid any spark.
Never use tools. If the knob will not turn by hand, do not try to force it; call a qualified
service technician. Forced repair may result in a fire or explosion due to gas leaks.
•Be sure to check next to the bottom of the unit because some gases are heavier than air
and may settle towards the floor.
•Check the GAS PRESSURE. Refer to p. 14.
•Do not try to light the burner manually. It is equipped with an electronic ignition device
which automatically lights the burner.
•Check for PROPER VENTING and COMBUSTIBLE AIR to the heater.
•Purge the GAS and WATER LINES to remove any air pocket.
•Do not use this water heater if any part has been submersed under water. Immediately call
a qualified service technician to inspect the water heater and to replace any damaged
parts.
CAUTION: IF YOU SMELL GAS:
•Do not try to start the water heater.
•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.
1. Once the above checks
have been completed,
please clean filter of any
debris. Refer to p. 23 for
instructions.
2. Fully open the manual
water control valve on the
water supply line.
3. Open a hot water tap to
verify that water is flowing
to that tap.
Then close the hot water tap.
4. Fully open the manual
gas control valve
installed.
5. Turn on the 120 volt 60 Hz
power supply to the T-K3-
OS/SP water heater.
6. Now you are ready to
enjoy hours of endless
hot water.
FOR YOUR SAFETY, READ BEFORE OPERATING:

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NORMAL OPERATION
•Flow rate to activate the T-K3-OS/SP : 0.5 gallon per minute
•Flow rate to keep the T-K3-OS/SP running : 0.4 gallon per minute
1. NORMAL OPERATION
WITHOUT REMOTE CONTROLLER
1. Open a hot water tap. 2. Mix cold water with the hot to get
the correct temperature water.
3. Close the hot water tap.
2. NORMAL OPERATION
WITH REMOTE CONTROLLER: TK-RE02 (Optional)
1. Press the operation ON/OFF button.
2. Set temperature. (Example: 104°F)
The temperature options (unit: °F)
99 100 102 104 106 108 110 111 113 115 117 122 131 140 158 167
•Temperature settings 140°F and above are for heating applications only.
3. Open a hot water tap.
Mix cold water with the hot if you need.
4. Close the hot water tap.
WARNING
Hot Water temperatures over 125°F can cause severe burns
instantly or death from scalding.
•The outlet hot water temperature of the FLASH T-K3-OS/SP
water heater is factory set at 122°F.
•Feel the water temperature before bathing or showering.
The temperature is
displayed on the remote
controller when the remote
controller is ON.
Lamp is ON Lamp is OFF