T-KD20 Instantaneous Water Heater
Installation Manual and Owner’s Guide
Flash Water Heater
Model T-KD20
Suitable for potable water heating and space heating
Indoor Installation Only
FEATURING
• ENDLESS HOT WAT ER
• 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 (888) 882-5244
www.takagi-usa.com
FOR YOUR SAFETY - This product
must be installed and serviced by a
qualified professional service technician
or licensed person, 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 st o r e or use gaso line or other
flammable vapors or liquids in the
vicinity of this or any other gas
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 instruc tio n s.
•
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 Conten t s
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………………………………… 5
General…………………………… 5
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
Installation…………………….…... 11
Combustible Air Supply and
Ventilation………………. 11
Combustion air supply… 12
Manufactured Home (Mobile Home)
Installation……………….………... 12
Initiating the Appliance……... 12
Initial Operation…………………... 12
Maintenance…………………… 13
Troubleshooting……………….. 13-14
Applications…………………………..……. 15
Space Heating Application……….. 15-16
Storage Tank……………………... 17
Recirculation……………………… 17
Optional Items……………………………. 21
TK-RE01………………………….. 21
TK-BK01………………………….. 21
TK-TV01…………………………... 21
TK-TV03…………………………... 21
Dipswitch Settings………………………... 22
Indoor NG Dipswitch Settings… 22
Outdoor NG Dipswitch Settings…. 22
Indoor LP Dipswitch Settings… 23
Outdoor LP Dipswitch Settings… 23
Exploded Diagrams………………………. 24-27
Parts List………………………………….. 28
Flow Chart……………………………….. 29
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 and 14” WC for li quid Propa ne
gas, call the Gas Supplier.
• 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.
Thank you for purchasing this water heater.
Properly installed and maintained, it should give
you years of trouble free service. Read this
installation manual before system install to
applications whether with or without experience.
For Your Safety
PLEASE READ THIS MANUAL CAREFULLY AND
FOLLOW IT EXACTL Y FO R YOU R SAF ET Y.
1. Follow all local codes, or in the absence of local
codes, follow the most recent edition of the Nat ional
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 even above 5º F (-15º C )
ambient temperature. Refer to the sections on
Winterizing and the Freeze Prevention Device for
more information.
7. WARNING: Before bathing or showering always
check t he water temp erat ure. Do no t lea ve c hildre n
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.
Terms
Direct Vent: Also known as Sealed Combustion.
Systems are all air for combustion is derived directly
from the outside atmosphere and all flue gases are
discharged to the outside atmosphere. All Takagi
products flue gas vents are pressurized, requiring
careful sealing of all joints.
Category III Vent: A system that operates with a
positive vent static pressure and with a vent gas
temperature. All Takagi products flue gas vents are
positive pressure, it requires perfect seal of all vent pipe
joints.
Rating plate
Operation
General
The Flash Water Heater is an instantaneous, tankless
water heater designed to efficiently supply domestic or
commercial hot water and space heating applications.
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 burner on,
but after the burner are ignited, the flow rate can drop to
0.6 gallons per minute without the burner 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 th e Fla s h wat e r he at e r
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. Flo w will diminish, unit will shut off.
3. “Fire On” lamp will go out.
Temperature
The output temperature of the T-KD20 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. C onsult 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-KD20 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-KD20 is
rated for 250 gallons per hour, or 4.2 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-KD20 can do in a household application.
Remember that for bathing, cold water will be mixed for
a comfortable temperature, increasing the flow output
rate.
Househol d Flow Ra t e s
Appliance / Use
Flow Rate
(GPM)
Lavato r y Fau c et 1.0
Bath Tub 4.0
Shower 2.0
Kitchen Sink 1.5
Dishwasher 1.5
Washing Machine 2.0
Taken from UPC 1997
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 even
5º F (-15º C) in ambient temperature, 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 cont rol valve located on the gas
supply line.
6. Turn on the power supply to the Flash Water Heater.
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 and space
heating. 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 electric al 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
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 TAK AGI- U SA
Check that all the parts listed below were included with
the unit.
Electrical Connections
The T-KD20 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.
Refer to the following wiring diagrams. W iring diagrams
are also printed on the inside panel of the appliance.
Wiring Diagram
Elect r ical Rat ing
120 VAC, 60 Hz, 0.8 A.
Note : I f an y of the o r i gi nal wi ri ng s up pl i ed with th is ap pl i anc e mu st be re pl ac e d, it m ust be re pl ac ed
with appliance wiring material (180c) or its equivalent. Wires are available through the manufacturer.
Gas Supply Piping
Attention: Proper gas pressure is important but gas
volume is more critical than pressure. Right volume gas
supplies to system can be expect full performance. You
may calculate right gas pipe for right volume supply.
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 is 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
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