Takagi T-K2 User manual

T-K2 Instantaneous Water Heater
Installation Manual and Owner’s Guide
Flash Water Heater
Model T-K2
Suitable for potable water heating and space heating
FEATURING
•ENDLESS HOT WATER
•ON DEMAND
•COMPACT, SPACE SAVING
•ENERGY CONSERVING
•COMPUTER CONTROLS
•COMPUTERIZED SAFETY
•NO PILOT LIGHT
Takagi Industrial Co. USA Inc.
6 Goddard
Irvine, CA 92618
Toll Free [phone]
www.takagi-usa.com
FOR YOUR SAFETY - This product
must be installed and serviced by a
professional service technician or
licensed person, qualified in water
heater installation. Operation creates
carbon monoxide gas and flue gases,
which can cause serious injury or
death. Improper installation and/or
operation, or installation by an
unqualified person, will void 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.
•Do not store or use gasoline or other
flammable vapors or liquids in the
vicinity of this or any other
appliance.
•WHAT TO DO IF YOU SMELL GAS
•Do not use any appliance.
•Do not touch any electrical
switch, do not use any phone
in your building.
•Immediately contact your gas
supplier from another
location. 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.

Table of Contents
Specifications…………………………….. 2
For Your Safety…………………………...3
Operation…………………………………. 4
General…………………………… 4
Turning It On……………………… 4
Turning It Off……………………… 4
Temperature……………………… 4
Flow……………………………….. 4
Freeze Protection………………... 5
Installation………………………………… 6
General…………………………… 6
Accessories………………………. 6
Electrical Connections…………... 6
Wiring Diagrams…………………..7,8
Gas Supply Piping………………. 9
Water Plumbing………………….. 10
Pressure Relief Valve……………. 10
Wall Hanging Installation………... 11
Standing Installation……………... 11
Outdoor Installation……………… 11
Indoor Installation………………... 12
Combustible Air Supply…. 12
Exhaust Venting…………. 13
Manufactured Home (Mobile Home)
Installation……………….………... 13
Indoor……………………… 13
Outdoor……………………. 13
Initiating the Appliance…………... 14
Initial Operation…………………... 14
Space Heating Application……….. 15
Applications………………………. 19
Storage Tank……………... 19
Recirculation……………… 19
Maintenance……………………………… 20
Troubleshooting………………………….. 20-22
Optional Items……………………………. 23
TK-RE01………………………….. 23
TK-BK01………………………….. 23
TK-TV01…………………………... 23
TK-TV03…………………………... 23
TK-TV04…………………………… 23
Dipswitch Settings………………………... 24
Indoor NG Dipswitch Settings…… 24
Outdoor NG Dipswitch Settings…. 24
Indoor LP Dipswitch Settings……. 25
Outdoor LP Dipswitch Settings….. 25
Exploded Diagrams………………………. 26-29
Parts List………………………………….. 30
Flow Chart……………………………….. 31
Specifications
Natural Gas Input Min. 20,000 Btu
Max. 185,000 Btu
LPG Input Min. 19,000 Btu
Max. 175,000 Btu
Gas Connection ¾” NPT
Water Connections ¾” NPT
Water Pressure Min. 15 psi
Max. 150 psi
Natural Gas Pressure Inlet Min. 5” WC
Max. 10.5” WC
LP Gas Pressure Inlet Min. 11” WC
Max. 14” WC
Manifold Pressure Natural 2.3” WC
Propane 2.5” WC
Weight 60 lbs.
Dimensions 24.5”x16.5”x8.3”
Ignition Electronic Ignition
Electrical Supply AC 120 V
***
•Inlet gas pressure must not exceed the
above maximum values.
•For gas pressures lower than 5” WC for
natural gas, call the manufacturer.
•Before installing in areas over 4,500 feet
above sea level, contact the manufacturer
for high altitude adjustment instructions.
•Check the rating plate to insure this
product matches your specifications.
•Takagi - USA is constantly improving our
products, therefore specifications are
subject to change without prior notice.

For Your Safety
PLEASE READ THIS MANUAL CAREFULLY
AND FOLLOW IT EXACTLY FOR YOUR
SAFETY.
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 USA or the CGA
standard, CAN/CGA B149.1 or .2
Installation Codes for Gas Burning
Appliances 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 to install your Flash
Water Heater. Insure that your heater will
have enough combustible air, proper
ventilation, and locate your heater where
water leakage will not do damage to
surrounding areas. If there is a possibility
of water damage, install a suitable drain
pan under the unit, which will not restrict
combustible airflow.
4. Check the rating plate for the correct gas
type, gas pressure, water pressure, and
electrical rating. Do not install this unit if
these requirements can’t be met.
5. If a problem should occur, turn off all hot
water taps and turn off the gas. Call a
trained technician, the Gas Company, or
the manufacturer.
6. WARNING: Do not disconnect the
electrical supply if the temperatures will be
near freezing. The Freeze Prevention
Device will only work if the unit has proper
electrical power. The Freeze Prevention
Device is rated for temperatures down to
5º F (-15º C) in a wind free environment.
The wind chill factor will cause the Flash
Water Heater to freeze and be damaged at
temperatures above 5º F (-15º C). Refer to
the sections on Winterizing and the Freeze
Prevention Device for more information.
7. WARNING: Before bathing or showering
always check the water temperature. Do
not leave children or the infirm
unsupervised in the shower or bath. The
water temperature is set at 120º F (50º C)
from the factory to maximize the amount of
hot water you can use. Water temperature
over 125º F can cause severe burns
instantly or death from scalds.
8. WARNING: Do not use this appliance if
any part has been underwater.
Immediately call a certified and trained
technician to inspect and service the unit if
necessary.
9. WARNING: Do not store or use gasoline or
other flammable vapors or liquids in the
vicinity of this or any other appliance.
10.WARNING: Do not reverse the water and
gas connections, this will damage your
heater and can cause severe injury or
death from scalds. Follow the diagram
below when installing your Flash water
heater.
Rating plate

Operation
General
The Flash Water Heater is an instantaneous,
tankless water heater designed to efficiently
supply domestic or commercial hot water. The
principle behind the Flash water heater is
simple: Once a hot water tap is opened, the
Flash’s flow sensor detects that hot water is
needed, and automatically commands the
computer to electronically ignite the burners,
and heat water. During operation, the
computer monitors the water temperature and
flow rate, and controls the gas flow and fan
speed to maintain a constant output
temperature. After the burners are ignited the
“fire on” lamp will be lit.
0.75 gallons per minute is required to turn the
burners on, but after the burners are ignited,
the flow rate can drop to 0.6 gallons per
minute without the burners turning off.
As long as water, gas and electricity are
connected, there will be an endless flow of hot
water. To turn on your water heater, just open
a tap. To turn the heater off, just close the tap.
Turning It On
To turn on the Flash water heater
1. Open a hot water tap, or turn on water
demanding appliance.
2. Unit will detect flow, burners will ignite,
“Fire On” lamp will light up.
3. If necessary, mix in cold water to get a
comfortable temperature.
Turning It Off
To turn off the Flash water heater
1. Close the hot water tap, or turn appliance
off.
2. Flow will diminish, unit will shut off.
3. “Fire On” lamp will go out.
Temperature
The output temperature of the T-K2 has been
factory set for a maximum 120°F (50°C).
This is electronically controlled by the
computer and can be adjusted with a TK-
RE01 temperature controller, or with the
dipswitches on the computer board (See pgs.
21-22 for dipswitch settings). Further
adjustment may be made by mixing in cold
water with the hot to obtain the ideal water
temperature.
The flow rate possible out of the unit is
dependent on the temperature setting chosen.
Consult the flow charts on the last page of this
unit to determine the possible outlet
temperature and flow rate combinations.
WARNING: Temperatures above 125º F (52º
C) can cause severe burns or death from
scalding. Children, the disabled and the
elderly are at a high risk of being injured. Feel
the water temperature before bathing or
showering. Do not leave children, disabled
persons, or the elderly unsupervised.
Flow

The flow rate through the T-K2 is limited to a
maximum of 6.9 GPM. The temperature
setting, along with the supply temperature of
the water will determine the flow rate the unit
puts out. Consult the flow charts on the last
page of this manual to determine the possible
outlet temperature and flow rate combinations.
Based on the United States Department of
Energy method of testing water heater output,
the T-K2 is rated for 240 gallons per hour, or
4.0 GPM, at a 77°F rise above the inlet
temperature. Refer to the following chart of
typical household flow rates to determine what
the T-K2 can do in a household application.
Remember that for bathing, cold water will be
mixed for a comfortable temperature,
increasing the flow output rate.
Freeze Prevention
This unit comes equipped with heaters that
discourage the unit from freezing. For this
freeze prevention system to operate there has
to be electrical power to the unit.
The freeze prevention devices will not work if
the electrical power source is disconnected.
The unit has been rated for temperatures
down to 5º F (-15º C) in a wind free
environment. The wind chill factor will cause
the unit to freeze at temperatures above 5º F
(-15º C), even if the unit is installed indoors.
For indoor installation in areas where the
temperature will be well below freezing for
extended periods of time, use the thermostat
extension cable to extend the internal
thermostat to the outdoors, and install a TK-
TV03 backflow prevention kit so that cold air
will not backflow into the flue and cause the
unit to freeze. Do not install the water heater in
an area with extremely cold weather. This will
void your warranty and Takagi Industrial Co.
USA Inc. will not be responsible for any
damage that occurs.
WARNING: The pipe heaters are located on
the Flash Water Heater only. Any hot or cold
water pipes located outside of the unit will not
be protected. Properly protect and insulate
these pipes from freezing.
If the heater will not be in use for a long period
of time or if the temperatures will drop below
5º F (-15º C) with the wind chill factor, turn off
heater and drain the unit of water. This applies
to indoor and outdoor installations. This will
keep the unit from freezing and being
damaged.
Follow these instructions carefully:
1. Turn off the power supply to the Flash
Water Heater.
2. Close manual gas control valve.
3. Close manual water shut off valve.
4. Open all hot water taps in the house.
(Bathroom, kitchen, laundry room, etc.).
When the water flow has ceased, close all
hot water taps.
5. Have a bucket or pan ready to catch the
water from the unit’s drain plugs. Remove
the drain plugs to drain the water out of the
unit.
6. Let drain for 5 minutes.
7. Securely screw the drain plugs back into
place.
Follow these steps when it is again safe to use
the water heater:
1. Make sure all hot water taps are closed
and the drain plugs are securely attached.
2. Purge the water line of debris.
3. Open manual water control valve located
on the water supply line.
4. Open all the hot water taps to verify water
flows to the taps. Close hot water taps.
5. Open manual gas control valve located on
the gas supply line.
6. Turn on the power supply to the Flash
Water Heater.
Household Flow Rates
Appliance / Use Flow Rate
(GPM)
Lavatory Faucet 1.0
Bath Tub 4.0
Shower 2.0
Kitchen Sink 1.5
Dishwasher 1.5
Washing Machine 2.0
Taken from UPC 1997

Installation
General
All gas water heaters require careful and
correct installation to ensure safe and efficient
operation. This manual must be followed
exactly.
1. Read the For Your Safety section in the
beginning of this manual.
2. This unit is not capable of being used as a
pool or spa heater.
3. The regulator is preset at the factory. It is
computer controlled and should not need
adjustment.
4. Suitable for potable water heating only.
Well water or hard water may cause scale
problems that will not be covered by the
manufacturer’s warranty.
5. Maintain proper space for servicing. Install
the unit so that it can be connected or
removed easily.
6. Install so that the electrical power can be
switched off if necessary.
7. Avoid installing in an area with high levels
of dust, sand or debris. Particles may clog
the air vent, reduce fan function, or cause
improper combustion.
8. 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.
Accessories
Check that all the parts listed below were
included with the unit.
Electrical Connections
The T-K2 requires a 60 Hz 120 VAC electrical
power supply, and it should be properly
grounded in accordance with the most recent
edition of the National Electrical Code,
ANSI/NFPA 70 and any local codes. In
Canada, all electrical wiring to the heater
should be installed in accordance with the
Canadian Electrical Code, CSA C22.1 Part 1,
and any local codes. Do not rely on the gas or
water piping to ground the metal parts of the
heater.
CAUTION: Label all wires prior to
disconnection when servicing controls. Wiring
error can cause improper and dangerous
operation. Verify proper operation after
servicing.
•A means for switching off the 120 VAC
power supply must be provided.
•Wire the heater exactly as shown in the
wiring diagram.
•A green screw is provided in the junction
box for the grounding connection.
This section is for the installer. The
installer is responsible for the correct
installation of your Flash Water Heater.
For Your Safety: Only a certified and
trained service technician or qualified
plumber may service or install your
product.
Please keep this owner’s manual in a safe
place for future reference. Copies of this
manual are available from TAKAGI-USA

Refer to the following wiring diagrams. Wiring
diagrams are also printed on the inside panel of the appliance.
Wiring Diagrams
Electrical Rating
120 VAC, 60 Hz, 0.8 A.
Note : If any of the original wiring supplied with this appliance must be replaced, it must be replaced
with appliance wiring material (180c) or its equivalent. Wires are available through the manufacturer.

Gas Supply Piping
Check the rating plate to make sure that the
unit was built for the type of gas available in
the area.
The gas supply piping should be sized
according to the Applicable Plumbing Code for
a maximum draw of 185,000 BTUH. First
determine the effective length of the gas
supply line by measuring the actual length of
piping, and then adding 5 ft. for every elbow or
“T” to the actual length. Use the charts below
to determine the pipe diameter necessary to
accommodate the BTU demand of the unit. If
there are more gas drawing appliances on the
line, size according to the maximum amount of
BTU demand.
The gas supply pressures must be within the
ranges of the following chart:
Natural Gas
Supply Pressure Min. 5” WC Max. 10.5” WC
Propane Gas
Supply Pressure Min. 11” WC Max. 14” WC
Insufficient gas supply pressure can cause the
Flash Water Heater to lose efficiency or not
work at all.
WARNING: Fire or explosion may result if the
maximum supply pressures are exceeded.
The manifold gas pressure should be at
maximum 2.3” WC for natural gas, and 2.5”
WC for propane.
Always use approved connectors to connect
the unit to the gas line. Always purge the gas
line of any debris before connecting to the
water heater.
WARNING: Conversion of this unit from
natural gas to propane or propane to natural
gas cannot be done in the field. Contact your
local retailer or distributor to get the correct
unit for your gas type.
Always install a manual shutoff valve on the
gas supply line in case of an emergency, or if
service or maintenance is necessary.
This appliance and its individual shut-off valve
must be isolated from the gas supply piping
system by unplugging the unit and turning off
the main gas valve during any pressure testing
of the gas supply piping system at test
pressures equal to or less than ½ PSI.
When all of the connections have been made,
check the gas line for leaks. Apply soapy
water to all gas fittings and connections, if
bubbles form, there may be a leak.
Natural Gas Supply Piping
Based on 0.60 specific gravity for natural gas at .5” WC pressure drop
DOE standard is 1100 BTU per cubic ft. of natural gas
Pipe
Size Cubic Feet of Natural Gas
Length 10’ 20’ 30’ 40’ 50’ 60’ 70’ 80’ 90’ 100’ 125’ 150’ 200’
½” 174 119 96 82 73 66 61 56 53 50 44 40 34
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 Supply Piping
Based on 11” WC supply pressure
Pipe
Size kBTU of Propane
Length 10’ 20’ 30’ 40’ 50’ 60’ 70’ 80’ 90’ 100’ 125’ 150’ 200’
½” 275 189 152 129 114 103 96 89 83 78 69 63 55
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

Water Plumbing
Follow local guidelines for the length of the
plumbing line in order to ensure that there is
enough water pressure for all the fixtures on
the line. First, calculate the effective length of
the plumbing line by measuring the total length
of pipe, and then adding to this 5’ for each
elbow or tee in the line. Use the following
chart to determine the total number of fixture
units on the line, and then compare with the
chart at the bottom of this page to find the pipe
diameter and water pressure necessary.
Install with control valves on the inlet and
outlet, and use removable unions or
connectors to facilitate maintenance or service
if necessary.
If the water heater is installed in a closed
water system, means shall be provided to
control thermal expansion. Contact the water
supplier or a local plumbing inspector on how
to control this situation.
Purge the water line of air, and clean the filter
before initial operation.
WARNING: Do not reverse the hot outlet and
cold supply line connections to the Flash
Water Heater. Make sure the hot and cold
lines are connected as in the FOR YOUR
SAFETY section at the front of this manual.
Pressure Relief Valve
An approved pressure relief valve must be
installed in any installation with this unit. The
pressure relief valve must be installed on the
hot line out of the unit, with no check valves or
control valves between the unit and the relief
valve.
The Pressure relief valve must be rated for
150 PSI, and have a discharge capacity of
185,000 BTU. Connect the discharge opening
of the relief valve to a suitable drain to prevent
water damage should discharge occur.
If the pressure relief valve discharges
periodically, this may be due to thermal
expansion in a closed water supply system.
Contact the water supplier or local plumbing
inspector on how to correct this situation.
Do not plug the pressure relief valve. The line
should have no reduced fittings or other
restrictions and should allow for complete
drainage of valve and line. The pressure relief
valve should be manually operated once a
year to check for correct operation.
Should overheating occur or the gas supply
fail to shut off, turn off the manual gas control
valve to the appliance.
Length to the End of Hot Water Line and Recommended Fixture UnitsPressure Range 30 to 45 PSI Pressure Range 46 to 60 PSI Pressure Range 60+ PSI
Pipe
Size 100' 200' 300' 400' 100' 200' 300' 400' 100' 200' 300' 400'
3/4" 3-12 1-6 1-5 0-4 5-17 3-11 2-8 1-6 6-20 4-13 3-10 2-8
1" 12-25 6-17 5-13 4-12 17-36 11-25 8-20 6-18 20-39 13-32 10-26 8-22
1-1/4" 25-48 17-32 13-25 12-21 36-78 25-52 20-39 18-33 39-78 32-74 26-54 22-43
Fixture Unit Per Fixture (from UPC)
Plumbing Fixture
Description Fixture Unit
Combination Bath / Shower 4
Whirlpool Bath 4
Shower 2
Lavatory 1
Clothes Washer 4
Dishwasher 1.5
Kitchen Sink 1.5

Wall Hanging Installation
For a wall mount installation, use TK-BK01
brackets to securely attach the T-K2 to the
wall.
Locate the heater as desired, but follow all
applicable local codes, as well as the indoor or
outdoor clearances that apply to the
installation.
Standing Installation
If the unit is to be installed standing on a
surface, adjust the legs so that the unit stands
securely and is level (legs can be adjusted up
to 1”).
Do not install the unit standing directly on a
combustible surface. Use a 3” non-
combustible base.
Use the included L brackets to connect the
unit to a wall to ensure that it does not fall over.
These brackets will maintain the required 1”
clearance between the back of the unit and a
combustible surface.
Outdoor Installation
Follow all local codes, or in the absence of
local codes, follow the codes for Installation of
Gas Burning Appliances; National Fuel Gas
Code ANSI Z221.23 in USA or CAN/CGA
B149.1 or .2 in Canada.
For outdoor installation, purchase a TK-TV04
and install on the top of the unit.
Set the dipswitches for an outdoor installation
(See pgs. 21-22).
Locate the water heater in an open, unroofed
area, and maintain the following minimum
clearances from combustible and
noncombustible materials.
Outdoor Clearances
Piping side 6”
Front (Maintenance
space) 24”
Floor Non combustible
base Min. 3” off the
ground
Back of heater 1”
Non piping side 2”
Top of heater 36”
If this unit is installed under an overhang,
there must be a 36” clearance from the top of
the unit to the overhang, and the surrounding
area must be open in front and on the sides of
the unit.
WARNING: Do not have the flue terminal
pointing toward any opening into a building.
Do not locate your heater in a pit or any
location where gas and water can accumulate.

WARNING: Do not install the heater where
water, debris, or flammable vapors may get
into the flue terminal. This may cause damage
to the heater.
WARNING: United States regulations forbid
installing the unit within 4’ of any opening into
any building. Similar Canadian regulations
forbid the unit from being installed within 10’ of
any opening into any building.
WARNING: Improper installation can cause
nausea or asphyxiation from carbon monoxide
and flue gases which could result in severe
injury or death.
For installation in altitudes above 4,500 feet,
contact the manufacturer for instructions.
Indoor Installation
Follow all local codes, or in the absence of
local codes, follow the codes for Installation of
Gas Burning Appliances; National Fuel Gas
Code ANSI Z221.23 in USA or CAN/CGA
B149.1 or .2 in Canada.
WARNING: In an indoor installation, the T-K2
must be connected to a Category III special
gas vent in order to direct the dangerous
exhaust byproducts to the outdoors.
Connect the 4” Category III vent pipe to the 4”
round collar on the top of the unit.
WARNING: Do not install the unit directly on a
combustible surface such as carpeting, wood
floors, etc. If it is necessary to install the unit
standing on a surface, install a 3”
noncombustible base between the unit and the
surface.
Combustible Air Supply
The T-K2 must be installed in a location where
the proper amount of combustible air will be
available to it at all times. If the unit is
installed in a confined space, there must be
permanent openings supplying air to the unit.
If the openings will bring air directly from the
outdoors, two openings are required, and they
should be sized to give a minimum free area
of one square inch for every 4000 BTUH of the
maximum input rating of the unit.
Air Vents
T-K2 (47 sq. in.
each)
If the openings will bring air from another
indoor area, they should be sized to give a
minimum free area of one square inch for
every 1000 BTUH of the maximum input rating
of the unit.
Air Vents
(185 sq. in. T-K2
each)
One of these openings should be within 12” of
the ceiling, and the other should be within 12”
of the floor.

Exhaust Venting
This water heater must be vented in
accordance with the section on venting of
equipment in the latest edition of the National
Fuel Gas Code.
This is a Category III appliance, and must be
vented accordingly. The following are UL
listed manufacturers: ProTech Systems
FasNSeal, Z-Flex Inc. Z-Vent II and Heat-Fab
Inc. Saf-T Vent. This unit requires 4” vent pipe.
Connect the vent pipe to the unit so that it is
sealed airtight. Follow the vent pipe
manufacturer’s instructions when installing the
vent pipe. Do not common vent this appliance
with any other vented appliance.
The venting system must not exceed a length
of 35 ft. minus 5 ft. for every elbow. Do not
use more than 3 elbows.
No. of Elbows Max. Vertical or
Horizontal Length
035 ft.
130 ft.
225 ft.
320 ft.
If the horizontal vent run exceeds 5 ft., the
following criteria must be observed:
•There must be a 2” vertical run off the
top of the heater before the horizontal
run begins.
•The horizontal run must be supported
at 3’ intervals.
•The vent run should be pitched up
towards the termination at ¼” per foot.
The unit can be vented either up and out the
roof, or directly through a wall. If the unit will
be vented through a wall, use Takagi USA Inc.
optional part, the TK-TV01 vent terminator, or
an equal Category III vent part. Locate the
vent terminator according to ANSI
Z223.1/NFPA 54 and applicable local codes.
Maintain the following clearances to any
combustible surface in an indoor installation:
Indoor Clearances
Piping side 6”
Front (Maintenance
space) Suggested 24” Min. 4”
Floor Noncombustible base
Back of heater 1”
Non piping side 2”
Top of heater 12”
Manufactured Home (Mobile Home)
Installation
This appliance must be installed in
accordance with the Manufactured Home
Construction and Safety Standard, (Title 24,
CFR; Part 3280) and ANSI A119.5/NFPA
501D. In addition, install in accordance with
the following instructions, the instructions
supplied with any venting, local codes, utility
company requirements for the installation of
water heaters in manufactured homes (mobile
homes), and the latest edition of the National
Fuel Gas Code, ANSI Z221.3/NFPA 50.
Locate the heater in an enclosure separating
the unit from the internal atmosphere of the
manufactured home or trailer. All combustion
air must be obtained from the outside
atmosphere, and the flue gases must be
discharged directly outdoors through a gas
vent. There must be no opening from the
interior of the home or trailer into the water
heater enclosure.
Indoor Installation
Follow indoor installation instructions as set
out in an earlier section of this manual, except
that combustion air must not be taken from the
inside of the home or trailer.
Outdoor Installation
Follow outdoor installation instructions as set
out in an earlier section of this manual.
If the unit is to be installed in a recessed area,
connect a gas vent to the unit, which will direct
exhaust gases out of the recessed area.
Min. 32"
Min. 3"
Indoors Outdoors
Min. 3"

Initiating the Appliance
For your safety, read before operating.
WARNING: If you do not follow these
instructions exactly, a fire or explosion may
result causing property damage, personal
injury or loss of life.
a) This appliance does not have a pilot. It is
equipped with an electronic ignition device,
which automatically lights the burner. Do
not try to light the burner by hand.
b) Before operating, check for gas
accumulation in the area around the
appliance. Pay special attention near the
floor, because gas is often heavier than air,
and it may accumulate near the floor.
c) Do not attempt to open the manual gas
shutoff valve with anything but by hand.
Never use tools. If the valve will not open
by hand, do not try to repair it. Instead, call
a qualified service technician. Force or
attempted repair may result in a gas leak,
fire or explosion.
d) Do not use this appliance if any part has
been under water. Immediately call a
qualified service technician to inspect the
appliance and to replace any part that may
have been damaged by being under water.
WARNING: IF YOU SMELL GAS:
•Do not use 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.
Initial Operation
1. STOP! Do not operate without reading the
safety information first!
2. Switch off the electrical power supply to the
heater.
3. Do not attempt to light the burner manually.
4. Turn the manual gas control valve located
on the outside of the unit counterclockwise
to the OFF position.
5. Wait five (5) minutes to clear out any gas.
If you then smell gas, STOP! Follow “b” in
the “Initiating the Appliance” section above.
If you do not detect gas, proceed to the
next step.
6. Turn the manual gas control valve located
on the outside of the unit clockwise to the
ON position.
7. Turn on the electrical power to the
appliance.
8. Turn on any tap, and the T-K2 will initiate
itself.
9. If the appliance will not operate, follow the
instructions in the “Turning Off the Gas
Supply to the Appliance” section following,
and call a service technician or gas
supplier.
TURNING OFF THE GAS SUPPLY TO THE
APPLIANCE
Close the manual valve on the gas inlet line.
Turn off the power supply.
Manifold pressure tap.

Space Heating Application
The FLASH T-K2 can be used for space heating as well as potable heating of hot water
applications.
WARNING
•Toxic chemicals such as used for boiler treatments chemical, alcohol,
glycerol and glycol group will not be introduced into the system when used
for potable water and space heating.
•The FLASH T-K2 can be used to supply potable water and space heating and
shall not be connected to any heating system or component(s) previously
used with non-potable water where any chemicals were added to the water
heating appliances.
•When the system requires water for space heating at temperatures higher
than required for other used, a means such as a mixing valve shall be
installed to temper the water for those uses in order to reduce scald hazard
potential.
•Water temperature over 125 °F can cause severe burns instantly or death
from scalds.
•Chemicals such as diluted Glycol can be used for radiant floor, Hydro-warm
air or Baseboard heating only.
Basic system drawings and Schematics.
Heating application only:
Warning: This illustration is for concept only. There are a wide variety of variations to the
application of controls and equipment presented applications. Designers must add all
necessary safety and auxiliary equipment to conform to code requirements and design
practice.
For more details, contact Technical Department at [phone]
Make u
p
Water Su
pp
l
y
Ex
p
ansion Tank
Pressure Relief Valve
Air Vent
Pum
p
Radiant, Hydro or Baseboard
Heating Equipment.

Dual-purpose hot water heating (Domestic and Heating):
Priority Control Devices: It has a capability to make priority system that can be used as a
controller flow sensor, Aquastat, or electronic controller to controlling radiant, Hydro or
baseboard heating equipments.
Warning: Follow all local codes, or in the absence of local codes, follow the most recent
edition of the National Standard Code, ANSI Z21. 10.3.
Warning: This illustration is for concept only. There are a wide variety of variations to the
application of controls and equipment presented applications. Designers must add all
necessary safety and auxiliary equipment to conform to code requirements and design
practice.
For more details, contact Technical Department at (888) 882-524
Pressure Relief Valve
Air Vent Pum
p
Ex
p
ansion Tank
Radiant, Hydro or Baseboard
Heating Equipment.
Check Valve
Domestic
potable water
Cold water su
pp
l
y
Priorit
y
Control Devices

FOR YOUR SAFETY READ BEFORE OPERATING
A. This water heater does not have a pilot. It is equipped with an ignition device that
automatically lights the burner. Do not try to light the burner by hand.
B. BEFORE OPERATING smell all around the water heater area for evidence of
leaking gas. Be sure to smell next to the floor because some gas is heavier than air
and will settle on the floor.
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.
C. Use only your hand to turn the gas valve knob. Never use tools. If the knob will not
turn by hand, don't try to repair it. Call a qualified service technician. Force or
attempted repair may result in a fire of explosion.
D. Do not use this water heater if any part has been under water. Immediately call a
qualified service technician to inspect the water heater and to replace any damaged
parts.
WARNING: If you do not follow these instructions exactly, a fire or
explosion may result causing property damage, personal injury or loss of
life.
OPERATING INSTRUCTIONS
1. STOP! Read the safety information above or in the Owners Manual.
2. Turn off all electric power to the water heater.
3. Do not attempt to light the burner by hand.
4. Turn the gas manual gas valve located on the outside of the unit clockwise ↻to the
off position.
5. Wait five (5) minutes to clear out any gas. If you then smell gas. STOP! Follow "B"
in the safety information above on this label. If you don't smell gas, go to next step.
6. Turn the manual gas valve located on the outside of the unit counter clockwise ↺to
the ON position.
7. Turn on all electrical power to the water heater.
8. If the water heater will not operate, follow the instructions " to Turn Off Gas to water
heater" and Call your service technician or gas supplier.
TO TURN OFF GAS TO APPLIANCE
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.

Vapors from flammable liquids will explode and catch fire causing death or severe burns.
Do not use or store flammable products such as gasoline, solvents or adhesives in the
same room or area near the water heater.
WARNING: Do not install water heater where flammable products will be stored.
Read and follow water heater warnings and instructions. If owner's manual is
missing, contact the retailer or manufacturer.
WARNING
The outlet hot water temperature of the T-K2 water heater is factory set 120 °F.
WARNING: Use this heater at your own risk. The set outlet water temperature can cause
severe burns instantly or death from scalds. Test the water before bathing or showering.
Do not leave children or the infirm witho
ut supervised
DANGER
Keep flammable products:
1. Far away from heater.
2. In approved containers.
3. Tightly closed
4. Out of children's reach
Vapors:
1. Cannot be seen
2. Vapors are heavier than air
3. Go a long way on the floor
4. Can be carried from other rooms
to the main burner by air currents.
DANGER
Hot Water Heater temperature over 125 °F can cause
severe burns instantly or death from scalding.
Children, disabled and elderly are at the highest risk of
being scalded.
Feel water temperature before bathing or showering.
Temperature limiting valves are available, ask professional
person.
WARNING: California Proposition 65 lists chemical substances known to the state to
cause cancer, birth defects, death, serious illness or other reproductive harm. This product
may contain such substances, be their origin from fuel combustion (gas, oil) or
components of the product itself.

Applications
The T-K2 can be installed in a variety of plumbing applications, which will provide more comfortable
domestic hot water. Contact Takagi for information on using this unit as a heat source.
T-K2 with Storage Tank
Hot Out Cold In
Relief Valve
Check
Valve
Hot Water
Recirculation
Recirc. Pump Pump
The maximum flow rate through the T-K2 is 6.9 GPM. If it is necessary to achieve higher flow rates
for longer periods of time, then it can be installed in conjunction with a storage tank. A pump will be
necessary to keep the water hot. We suggest a pump of 1/12 hp or greater depending on the
system.
Recirculation
Pressure Relief Valve
Hot Water to House
Cold Water Inlet
Hot Water Return
Pump (with/without Timer) Check Valves
This system will also need a pump of 1/12 hp or greater, depending on the application situation.
For more details, contact Technical department at [phone]