Takagi TK310UING Product Guide

TANKLESS

PRODUCT GUIDE

SAVE

ENERGY.

Energy-efficient, plentiful, and

endless supply of hot water.

Takagi has delivered innovative hot water solutions for

more than 70 years, and is sold exclusively by plumbing

wholesalers and contractors. Takagi’s selection of residential

and commercial tankless water heaters are unmatched for

SAVE

SPACE.

Compact size and wall-mounted to

free up valuable floor space.

SAVE

MONEY.

The smart choice that will save you a

substantial amount of energy.

1

quality and diversity. Anywhere hot water is needed, Takagi

provides an energy-efficient solution with long-lasting value

for years after installation. Takagi stands behind its products

and customeras with world-class service, combining cutting-

edge technology with committed people who take pride in

being the very best.

TANKLESS ADVANTAGE

HOW IT WORKS – THE PROCESS:

• A hot water tap is opened.

• The opened tap allows water to flow
through the water heater. An internal
water flow sensor detects this flow.

• Upon flow detection, the flow sensor
sends the activation signal to the
computer board.

• The computer automatically ignites the
burner.

• As water flows through the heat
exchanger, it absorbs heat from the
burner.

• By the time the water exits the heater,
it has reached the designated set
temperature.

• When the hot water tap is closed, the
water heater automatically turns off.

ENDLESS
HOT WATER

Heating water only as it’s being used
means you will never run out of hot
water again. After the few seconds
it takes for the water to reach the
designated set temperature, our
water heaters will continually provide
a steady flow of hot water for as
long as your application needs it.

*Takagi tankless water heaters provide endless hot
water when sized appropriately for your home’s
needs.

ENERGY
CONSERVATION

Provides you with continuous hot water
in one of the most energy-efficient
ways possible. Conventional tank-type
water heaters will heat and store a set
volume of water, regardless of whether
someone is using that hot water or not.
Because our tankless water heaters
only activate when hot water is being
used, no standby energy losses are
incurred, providing efficient heating
while conserving energy.

COMPACT
SIZE

On top of all this, an Takagi tankless
water heater takes up much less space
than your conventional tank-type water
heater or boiler. Takagi’s wall-mount
design offers flexible installations
freeing up valuable storage space.

2

SAFETY

At Takagi, we place the safety and
reliability of our products above all else.
By incorporating technologically advanced
safety features into every model, we
provide the assurance and peace of mind
that can only come from an Takagi quality
product.

Air-Fuel Ratio (AFR)
Sensor

Takagi’s unique AFR sensor monitors and
maintains proper combustion at all times.
Together with the onboard computer, this
system will adjust the fan motor speed to
ensure that air and fuel have a proper
mixture ratio, minimizing emissions and
maximizing efficiency.

Additional Safety
Features

Freeze Protection:

Every heater in Takagi’s tankless lineup has
an internal freeze protection system, which
is rated to protect the heaters when installed
in sub-freezing conditions. This system
works to keep water temperatures within the
heat exchanger from falling below a certain
level, preventing freeze damage.

Hi-Limit Switch:

HEAT EXCHANGER

IGNITER

AFR

FLAME SENSOR

BURNER

Ensures that water temperatures do not exceed safe levels. Before the water temperature can even reach these unsafe levels,
the hi-limit switch activates by disengaging the gas valves, effectively shutting down the water heater.

PVC Venting:

Indoor condensing models have a thermistor and hi-limit switch that monitor the exhaust temperature. If the exhaust
temperature nears an unsafe limit, these features regulate combustion and can shut the heater down to protect the integrity of
the PVC vent material.

Overheat Cutoff Fuse:

Ensures that there are no breaches in the heat exchanger drum. In cases where enough physical damage might have been
done to the water heater to lead to a breach in the heat exchanger drum, the overheat cutoff fuse reacts by shutting down the
water heater if the surface of the heat exchanger retains too much heat.

3

0.016" (0.4mm)

0.020" (0.5mm)

water

water

drum coil

drum coil

drum

25% Thicker

DURABILITY

0.020" (0.5mm)

HEAT EXCHANGER WITH COMMERCIAL-GRADE COPPER

Only Takagi incorporates true commercial-grade heat exchangers in our tankless heaters (D2, 510U/C, or 510U, 510C,
H3, 540P, CT-199 and M50 non-ASME models). All aspects of the heat exchanger are designed to add the durability and
reliability that is vital to any successful commercial organization or business.

Commercial-Grade Copper Alloy

Our commercial-grade copper is a heat-resistant copper alloy, with additive elements that make it much stronger and harder
than the standard C1220 copper used in most other heat exchangers. Our commercial-grade copper has 8 times the tensile
strength of regular copper. Even at high temperatures, our commercial-grade copper maintains a fine grain and high strength.
Commercial-grade copper provides resistance to the damaging effects of erosion that can cause heat exchangers to leak.

Commercial-Grade Copper Tubing

Drum Thickness

During every ignition cycle, thermal expansion causes all heat exchangers to undergo heat stress. After the thousands of ON/
OFF cycles typically seen in a commercial application, this heat stress can prove damaging. This is why the heat exchangers
in our commercial and light commercial products utilize drums that are 25% thicker, ensuring the longevity of our products. A
thicker drum creates less strain on the heat exchanger.

A thinner drum strains more

under heat stress

drum

water

drum coil

water

drum coil

A thicker drum creates less

strain on the heat exchanger

water

drum coil

water

25% Thicker

drum coil

drum

4

WATER VALVES

Making true commercial-grade water heaters involves more than just redesigning our heat exchangers—every internal component
has to measure up to Takagi’s commercial standards. Just like our advanced heat exchangers, the longevity and functionality of
components such as our water valves and flow sensors are also of great importance.

Our commercial-grade water heaters (D2, 510U/C, 510C, and T-H3), as well as our commercial water heaters (CT-199
and T-M50) feature a bypass and flow adjustment valve, which not only provide the optimal control and precision essential for
commercial usage, but also offer the durability needed to handle tough, high-volume conditions.

Stepper Motor Water Valves -

M50 Models

5

Bypass Valve - D2/510U/510C,

CT-199 and H3 Models

Flow Adjustment - D2/510U/510C

CT-199 and H3 Models

SECONDARY HEAT EXCHANGER 316L STAINLESS STEEL
(CONDENSING MODELS ONLY)

The secondary condensing heat exchanger is made of high-quality 316L stainless steel. This is where the rest of the heat
transfer occurs. Due to the lower temperature acidic condensation occurs, and stainless steel is required in order to avoid
corrosion.

For condensing heat exchangers, it is more suitable to use 316L stainless steel because of the extreme environment (heat,
acidic condensation, chloride) that the material is subjected to.

Secondary HX-Stainless Steel 316L

Bypass Valve

Hot Water Outlet

Flow
Sensor

Cold Water
Inlet

Primary HX
Commerical-Grade
Copper

Drum
Coil

Flow Adjustment
Valve

PRIMARY HEAT
EXCHANGER:
COPPER VS.
STAINLESS STEEL

• Heat transfers 25 times more readily
through copper than stainless steel.
Consequently, for the same amount
of heat transfer, stainless steel heat
exchangers need to be larger than
copper heat exchangers, leading to a
larger pressure loss.

• At higher temperatures, it is the nature
of stainless steel to become prone
to a number of problems not usually
experienced at room temperature. It is
vulnerable to pitting corrosion and stress
corrosion cracking (SCC).

• Stainless steel is NOT better for
durability because it is harder.
Hardness causes the material to
become brittle. Stainless steel will
crack after numerous cycles of
thermal expansion/contraction,
especially with chloride in the
water. Copper heat exchangers
are less brittle and better suited
for expansion/contraction without
cracking.

• In a

dual

heat exchanger design,
corrosion is not a big concern in
the non-condensing primary heat
exchanger because no condensation
forms on the exterior of the pipes.
Stainless steel is unnecessary for this
stage.

Note: H3M, H3J and H3S condensing line units use C1220
copper and do not have a bypass valve
* Diagram represents H3

6

WATER FLOW

Condensation can build up over time in any heat
exchanger, causing damage and premature leaks.
Takagi’s commercial models (M50 series) include
condensation reduction features that safeguard
against these types of damaging effects.

Better Water Pathway
Design

By redesigning and redirecting the flow of water,
the temperature of the heat exchanger drum and
finned coils stay elevated above dew point,
making it much more difficult for condensation to
build.

Fin Pitch

By widening the pitch of the heat exchanger fins,
not only do we improve durability by reducing
occurrences of blockage, we also maintain higher
temperatures on the upper finned coils. Keeping
these coils at elevated temperatures reduces the
likelihood of condensation buildup.

FIN

Finned Coil

90%-95% of total

heat absorbed)

Drum Coil
(5%-10%
of total heat
absorbed)

Hot Water Outlet
(100% heat absorbed)

No condensation
buildup on
drum coil

Burner

M

Bypass Valve

(M50)

Flow
Sensor

Cold Water Inlet

7

BASIC SIZING GUIDELINES

The flow rate capacity of tankless water heaters depends on
the temperature difference between the desired output and
incoming water temperature. The flow rate comparison chart
and table shown here summarize the flow rate charts found in
the specifications of each model.

Takagi water heaters are sized according to the peak flow
rate requirements, worst-case temperature-rise scenarios,
and types of applications. Once these factors have been
determined, refer to either the flow rate comparison here or

Application designers/engineers can decide whether
to size for full flow, expected flow, or utilize probability
models such as the modified “Hunter Curve.” For large
scale applications such as hotels, apartment complexes
and large restaurants, Hunter Curves are commonly used
to estimate the peak flow rate demand when given the
total amount of fixture units within an application. It is up
to the application designer/engineer to determine the
amount of fixture units within any given application.

the flow rate charts found in each model’s specifications.
Select the appropriate water heater as well as the amount of
water heaters required.

MATCH THE UNIT TO YOUR NEEDS

Warmer Climates

70°F Incoming Groundwater Temperature

Capacity - Number of Shower Heads

Non-Condensing Units

(Assuming the set point temperature is 120˚F )

Cooler Climates

50°F Incoming Groundwater Temperature

KJr2/110U/110C

K4/310U/310C

D2/510U/510C

Condensing Units

H3M

H3J

H3S

H3/540P

Commercial Units

M50

CT-199

2.5 Showers

3.5 Showers

3.5 Showers

2.5 Showers

3.5 Showers

4 Showers

4.5 Showers

7 Showers

4.5 Showers

1.5 Showers

2.5 Showers

2.5 Showers

1.5 Showers

2.5 Showers

2.5 Showers

3 Showers

5 Showers

3 Showers

8

FLOW RATE GUIDE

Temperature Rise vs. Gallons per Minute

Temp

Rise

30°

35°

40°

45°

50°

55°

60°

65°

70°

75°

80°

85°

90°

95°

100°

KJr2/

110U/

110C

K4/

310U/

310C

D2/

510U/

510C

H3M H3J H3S H3/540P CT-199 M50

6.6 8.0 10.0 6.6 6.6 8.0 10.0 10.0 14.5

6.6 8.0 9.3 6.4 6.6 8.0 10.0 10.0 14.5

5.7 7.8 8.1 5.6 6.6 8.0 9.5 9.5 14.5

5.1 6.9 7.2 5.0 6.6 7.6 8.4 8.4 13.5

4.6 6.2 6.5 4.5 6.1 6.8 7.6 7.6 12.2

4.2 5.7 5.9 4.1 5.5 6.2 6.9 6.9 11.1

3.8 5.2 5.4 3.7 5.1 5.7 6.3 6.3 10.1

3.5 4.8 5.0 3.4 4.7 5.3 5.8 5.8 9.4

3.3 4.4 4.7 3.2 4.3 4.9 5.4 5.4 8.7

3.1 4.1 4.3 3.0 4.1 4.6 5.0 5.0 8.1

2.9 3.9 4.1 2.8 3.8 4.3 4.7 4.7 7.6

2.7 3.7 3.8 2.6 3.6 4.0 4.4 4.4 7.2

2.5 3.5 3.6 2.5 3.4 3.8 4.2 4.2 6.8

2.4 3.3 3.4 2.3 3.2 3.6 4.0 4.0 6.4

2.3 3.1 3.3 2.2 3.0 3.4 3.8 3.8 6.1

Flow rate is determined by temperature rise. To determine your temperature rise, subtract the incoming water temperature from
the set output temperature. All units are factory set to 120°F or 122°F but can be changed.

Example of Hunter Curves for
Sizing Large Applications

100

90

80

70

60

50

40

30

Gallons Per Minute

20

10

0

0

Restaurants

Hospitals, Nursing Homes,
Dormitories, Hotels & Motels

75

25

50

125

150

175

225 325

200

Fixture Units

Apartments & Houses

Office Buildings & Schools

250

275

300

375

400

350100

Comparison of Flow Rates vs.
Temperature Rise

16

14

12

Flow Rate (gpm)

10

8

6

4

2

0

M50 D2/510U/510C H3/540P and CT-199

H3S K4/310U/310C

H3J

H3M

Temperature Rise (°F)

140120100806040200

KJr2/110U/110C

9

SIMPLE TANKLESS SIZING

TANKLESS MODELS
GROUND WATER TEMPERATURE
FACTO R

The temperature of incoming ground water
(cold water inlet temperature) varies greatly
throughout the U.S. and also fluctuates
with the changing of the seasons. The
temperature of water as it enters the
water heater will determine the amount of
“temperature rise” required to achieve the
desired hot water outlet temperature (120°F
is recommended).

The best way to measure incoming ground
water temperature is to use a thermometer
to measure cold water temperature during
the coldest season of the year. To simplify
the process, use this map to determine
whether your installation location is in the
Southern Zone, Central Zone or Northern
Zone.

PEAK HOT WATER DEMAND

The next step is to determine how many
gallons per minute of hot water will be
required during the busiest usage period
(peak demand). Consider all appliances
and fixtures that use hot water, including
lavatory faucets, kitchen faucets, washing
machines, dishwashers, showers and
bathtubs. Be sure to determine how many
appliances and fixtures will be used at the
same time (peak demand).

Average Ground Water Temperature

Average Ground Water

Temperature: 62°F to 77°F

Average Ground Water

Temperature: 52°F to 61°F

NORTHERN ZONESOUTHERN ZONE CENTRAL ZONE

Average Ground Water

Temperature: 37°F to 51°F

Remember, these are general recommendations. Your Takagi Water Heater Specialist can review your family’s
needs in even greater detail to make sure the model you choose will always provide enough hot water to meet
the demand.

10

KJR2 SERIES

The KJr2 Series is great for apartments, one bath homes in cold climates, condos and
summer cabins. A remote control is included as a standard feature.

T-KJR2-IN

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-KJr2-IN-N Natural 19,500 140,000 4.0 10.5 0.79

Model Number*

T-KJr2-IN-N 6.6 3/4" NPT 3/4" NPT 12 12 3 4 38

*For propane models, change “N” to “P”
**For propane models, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

KJr2
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 113°F 122°F (default) 131°F 140°F

With 100112183 remote (max. distance 150’ from heater, non-polarized 20 gauge wiring.)

99°F to 167°F (16 options), 122°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

73 W / 0.61 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

6 W / 0.05 A
(Standby)

111 W / 0.93 A
(Freeze-Protection)

Maximum

(in. W.C.)

Approx

Shipping

Weight (lbs)

UEF

11

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

2-1/4" (56 mm) COLD
3-7/8" (98mm) GAS

4-7/8" (124mm) HOT

1" (26mm)

4" (102mm)

4-7/8" (123mm) 120V

7-3/4" (196mm)

2-1/4" (57mm)

Specifications

KJr2: Flow Rate vs. Temperature Rise

KJr2: Pressure Loss

Head (ft)

Indoor installation only

Power Vent or Power Direct Vent
Design

Low NOx Emissions

4” Category III Vent

Flow Rate up to 6.6 GPM

• Values based on factory testing. 0.4 GPM required
for continuous fire after initial ignition

Dimensions

13-3/4" (350mm)

10" (254mm)

4" (101 mm)

1-3/4" (45mm)1-3/4" (45mm)

2-1/4" (56mm)

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 140,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

4" (102mm)

21-3/8" (544mm)

1-7/8" (47mm)

COLD 3-1/8" (79mm)
HOT 5-1/4" (133mm)

KJr2: Flow Rate vs. Temperature Rise

9.0

8.0

7.0

6.0

5.0

4.0

Flow rate (gpm)

3.0

2.0

1.0

0

Temperature rise (°F)

10 30

20-1/4" (520mm)

120V 1-3/8" (36mm)
GAS 4-7/8" (124mm)

50

70 90 110

100806040200.0

KJr2: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

Flow Rate (gpm)

2-1/4" (57mm)

1" (26mm)
2-1/4" (56 mm) COLD
3-7/8" (98mm) GAS
4-7/8" (123mm) 120V
4-7/8" (124mm) HOT
7-3/4" (196mm)

120

110

100

90

80

70

60

50

Head (ft)

40

30

20

10

0

8.06.0402.00.0

12

K4 SERIES

The K4 features a max flow rate of 8.0 gpm, providing enough hot water for a home with
up to three showers at the same time. A remote control is included as a standard feature.

T-K4-OS

T-K4-IN

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-K4-IN-N Natural 11,000 190,000 4.0 10.5 0.80
T-K4-OS-N Natural 11,000 190,000 4.0 10.5 0.80

Model Number*

T-K4-IN-N 8 3/4" NPT 3/4” NPT 12 12 3 4 43

T-K4-OS-N 8 3/4" NPT 3/4” NPT 36 12 3 24 43

*For propane models, change “N” to “P”
**For propane models, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

K4
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 113°F 122°F (default) 131°F 140°F

With 100112183 remote (max. distance 150’ from heater, non-polarized 20 gauge wiring.)

99°F to 167°F (16 options), 122°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

88 W / 0.73 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

6 W / 0.05 A
(Standby)

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

111 W / 0.93 A
(Freeze-Protection)

Approx

Shipping

Weight (lbs)

UEF

13

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

HOT

COLD 3-1/4" (84mm)

1-5/8" (43mm)

9-1/2" (241mm)

K4: Pressure Loss

Head (ft)

K4: Flow Rate vs. Temperature Rise

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Low NOx Emissions

4” Category III Vent

Flow Rate up to 8.0 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 190,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

13-3/4" (350mm)

10" (254mm)

1-3/4" (45mm) 1-3/4" (45mm)

4" (101 mm)

1-3/8" (36mm)

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

4-3/8" (113mm)

K4: Flow Rate vs. Temperature Rise

9.0

8.0

7.0

6.0

5.0

4.0

3.0

Flow rate (gpm)

2.0

1.0

0

10

Temperature rise (°F)

21-3/8" (544mm)

20-1/4" (520mm)

1-7/8" (47mm)

5-1/4" (133mm)

30

120V 1-3/8" (36mm)

GAS 4-7/8" (124mm)

50 70 90 110

100806040200.0

K4: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

1.0 3.0 5.0 7.0 9.0

Flow Rate (gpm)

1" (26mm)

COLD 2-7/8" (71mm)

120VAC 3-7/8" (99mm)

GAS 5-1/4" (135mm)

HOT 6-1/2" (164mm)

19-3/8" (493mm)

120

110

100

90

80

70

60

50

40

Head (ft)

30

20

10

8.06.0402.00.0

0

14

D2 SERIES

The D2 series is well suited for residential/commercial applications such as small restaurants
and beauty salons. Utilizing commercial grade copper alloy for the heat exchanger tubing, the
D2 series is also suitable for heavier residential usages such as combination space heating and
domestic recirculation systems. A remote control is included as a standard feature.

T-D2-INT-D2-OS

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-D2-IN-N Natural 11,000 199,000 4.0 10.5 0.80
T-D2-OS-N Natural 11,000 199,000 4.0 10.5 0.80

Model Number*

T-D2-IN-N 10 3/4" NPT 3/4” NPT 12 12 3 4 45

T-D2-OS-N 10 3/4" NPT 3/4” NPT 36 12 3 24 45

*For propane models, change “N” to “P”
**For propane models, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

D2
Temperature
Settings

Electric 120 V 90 W / 0.75 A 6 W / 0.05 A

Maximum

GPM

Dipswitches 104°F 113°F 122°F (default) 140°F

With 100112155 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 176°F (15 options), 122°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

Maximum

(BTU/H)

Gas

Connection

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

111 W / 0.93 A
(Freeze-Protection)

Approx

Shipping

Weight (lbs)

UEF

15

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

D2: Pressure Loss

Head (ft)

HOT

COLD 3-1/4" (84mm)

1-5/8" (43mm)

9-1/2" (241mm)

D2: Flow Rate vs. Temperature Rise

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Low NOx Emissions

4” Category III Vent

Flow Rate up to 10.0 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 199,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

13-3/4" (350mm)

10" (254mm)

1-3/4" (45mm) 1-3/4" (45mm)

4" (101 mm)

1-3/8" (36mm)

Easy-Link up to 4 heaters

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

4-3/8" (113mm)

D2: Flow Rate vs. Temperature Rise

12

10

8

6

Flow rate (gpm)

4

2

0

Temperature rise (°F)

21-3/8" (544mm)

20-1/4" (520mm)

1-7/8" (47mm)

5-1/4" (133mm)

120V 1-3/8" (36mm)

GAS 4-7/8" (124mm)

Set temperature: 122°F or lower
Set temperature: 131°F or higher

19-3/8" (493mm)

1" (26mm)

COLD 2-7/8" (71mm)

120VAC 3-7/8" (99mm)

GAS 5-1/4" (135mm)

HOT 6-1/2" (164mm)

D2: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

140120100806040200

0

Flow Rate (gpm)

8.0 10.06.0402.00.0

Set temperature: 122°F or lower

Set temperature: 131°F or higher

120

110

100

90

80

70

60

50

40

30

20

10

Head (ft)

0

16

110C SERIES

The 110C Simplicity Series is fuel convertible out of the box and easily installs using contractor
preferred concentric venting. Great for apartments, one bath homes in cold climates, condos
and summer cabins.

TK-110C-NI

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-110C-NI Natural 15,000 140,000 4.0 10.5 0.81

Model Number*

TK-110C-NI 6.6 3/4" NPT 3/4” NPT 12 12 3 4 55

*Indoor models only. Units are field convertible from natural gas to propane with supplied conversion kit.
**For propane, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

110C
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120 °F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100 °F to 140 °F (9 options), 120 °F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

53 W / 0.58 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

Minimum (in.

W.C.)

Clearances (in.)

Top Bottom Side Front

2 W / 0.06 A
(Standby)

Maximum (in.

W.C.)

Approx

Shipping

Weight (lbs)

99 W / 0.83 A
(Freeze-Protection)

UEF

17

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

110C: Flow Rate vs. Temperature Rise

110C: Pressure Loss

Head (ft)

10-1/2” (266.5 mm)

5-7/16” (137.7 mm)

19-1/2” (495.7 mm)

1.0” (25.5 mm)

5-7/16” (137.7 mm)

Top view

Installations are simple and flexible with
contractor-preferred concentric venting

Long venting runs up to 43 feet and
operates in altitudes up to 10,100 feet

Gas convertible from natural gas to
propane using the included conversion kit

Flow Rate up to 6.6 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Meets Ultra-Low NOx requirements

Dimensions

13-3/4” (350 mm)

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 140,000 btu/h,
150 psi)

• 40 psi or above recommended for max. flow

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

10-1/2” (266.5 mm)

5-7/16” (137.7 mm)

1.0” (25.5 mm)

110C: Flow Rate vs. Temperature Rise

9.0

8.0

7.0

6.0

5.0

4.0

Flow rate (gpm)

3.0

2.0

1.0

0

10 30 50 70 90 110

Temperature rise (°F)

6040200.0

20-1/2” (520 mm)

80

100

110C: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

Flow Rate (gpm)

19-1/2” (495.7 mm)

8.06.0402.00.0

120

110

100

90

80

70

60

50

40

30

20

10

0

Head (ft)

18

310C SERIES

The 310C Simplicity Series is fuel convertible out of the box and easily installs using
contractor preferred concentric venting. It generates a max flow rate of 8.0 gpm, providing
enough hot water to run three showers at the same time.

TK-310C-NI

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-310C-NI Natural 15,000 190,000 4.0 10.5 0.82

Model Number*

TK-310C-NI 8 3/4" NPT 3/4” NPT 12 12 3 4 55

*Indoor models only. Units are field convertible from natural gas to propane with supplied conversion kit.
**For propane, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

310C
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100 °F to 140 °F (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

71 W / 0.81 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

2 W / 0.06 A
(Standby)

Minimum (in.

W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum (in.

W.C.)

99 W / 0.83 A
(Freeze-Protection)

Approx

Shipping

Weight (lbs)

UEF

19

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

10-1/2” (266.5 mm)

5-7/16” (137.7 mm)

19-1/2” (495.7 mm)

1.0” (25.5 mm)

5-7/16” (137.7 mm)

Top view

310C: Pressure Loss

Head (ft)

310C: Flow Rate vs. Temperature Rise

10.0

Installations are simple and flexible with
contractor-preferred concentric venting

Long venting runs up to 43 feet and
operates in altitudes up to 10,100 feet

Gas convertible from natural gas to
propane using the included conversion kit

Flow Rate up to 8.0 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition.

Meets Ultra-Low NOx requirements

Dimensions

13-3/4” (350 mm)

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 190,000 btu/h,
150 psi)

• 40 psi or above recommended for max. flow

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

10-1/2” (266.5 mm)

5-7/16” (137.7 mm)

1.0” (25.5 mm)

310C: Flow Rate vs. Temperature Rise

9.0

8.0

7.0

6.0

5.0

4.0

Flow rate (gpm)

3.0

2.0

1.0

0

Temperature rise (°F)

20-1/2” (520 mm)

Pressure Loss (psi)

100806040200.0

310C: Pressure Loss

100

90

80

70

60

50

40

30

20

10

0

Flow Rate (gpm)

19-1/2” (495.7 mm)

8.06.0402.00.0

200

180

160

140

120

100

80

60

40

20

Head (ft)

0

20

510C SERIES

The 510C Simplicity Series is fuel convertible out of the box and easily installs using contractor
preferred concentric venting. It is well suited for residential/commercial applications such as
small restaurants and beauty salons. Utilizing commercial grade copper alloy for the heat
exchanger tubing, the 510C series is also suitable for heavier residential usages such as
combination space heating and domestic recirculation systems.

TK-510C-NI

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-510C-NI Natural 15,000 199,000 4.0 10.5 0.81

Model Number*

TK-510C-NI 10 3/4" NPT 3/4” NPT 12 12 3 4 55

*Indoor models only. Units are field convertible from natural gas to propane with supplied conversion kit.
**For propane, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

510C
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 160°F (13 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

72 W / 0.85 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

3 W / 0.07 A
(Standby)

100 W / 0.83 A
(Freeze-Protection)

Maximum

(in. W.C.)

Approx

Shipping

Weight (lbs)

UEF

21

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

510C: Flow Rate vs. Temperature Rise

10-1/2” (266.5 mm)

5-7/16” (137.7 mm)

19-1/2” (495.7 mm)

1.0” (25.5 mm)

5-7/16” (137.7 mm)

Top view

510C: Pressure Loss

Head (ft)

Installations are simple and flexible with
contractor-preferred concentric venting

Long venting runs up to 43 feet and
operates in altitudes up to 10,100 feet

Gas convertible from natural gas to
propane using the included conversion kit

Flow Rate up to 10 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition.

Meets Ultra-Low NOx requirements

Dimensions

13-3/4” (350 mm)

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 199,000 btu/h,
150 psi)

• 40 psi or above recommended for max. flow

Easy-Link up to 4 heaters or connect up to
20 heaters with a Multi-Unit Controller

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

10-1/2” (266.5 mm)

5-7/16” (137.7 mm)

1.0” (25.5 mm)

510C: Flow Rate vs. Temperature Rise

12
11

10

9

8

7
6
5
4

Flow rate (gpm)

3

2
1

0

Temperature rise (°F)

Set temperature: 125°F (52°C) or lower
Set temperature: 130°F (55°C) or higher

20-1/2” (520 mm)

140120100806040200

510C: Pressure Loss

100

90

80

70

60

50

40

Pressure Loss (psi)

30

20

10

0

Flow Rate (gpm)

19-1/2” (495.7 mm)

Set temperature: 125°F (52°C) or lower
Set temperature: 130°F (55°C) or higher

Set Temperature 125°F (52°C) or higher, maximum flow rate is limited to 8.0 gpm.

8.0 10.06.0402.00.0

220

200

180

160

140

120

100

80

60

40

20

0

Head (ft)

22

110U SERIES

The 110U Series is great for apartments, one bath homes in cold climates, condos and summer
cabins. Indoor models include an integrated temperature controller. A remote control is included
as a standard for outdoor models. Complies with SCAQMD Rule 1146.2 and other air quality
management districts with similar NOx Emission requirements of 14 ng/J or 20 PPM.

TK-110U-ETK-110U-I

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-110U-I Natural 15,000 140,000 4.0 10.5 0.81
TK-110U-E Natural 15,000 140,000 4.0 10.5 0.81

Model Number*

TK-110U-I 6.6 3/4" NPT 3/4” NPT 12 12 3 4 39

TK-110U-E 6.6 3/4" NPT 3/4” NPT 36 12 3 24 39

*Units are field convertible from natural gas to propane with supplied conversion kit.
**For propane, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

110U
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 140°F (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

54 W / 0.64 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

2 W / 0.06 A
(Standby)

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

96 W / 0.82 A
(Freeze-Protection)

Approx

Shipping

Weight (lbs)

UEF

NON-CONDENSING

23

ANSI Z21.10.3 • CSA 4.3

Specifications

110U: Flow Rate vs. Temperature Rise

100806040200.0

110U: Pressure Loss

Head (ft)

8.06.0402.00.0

120 VAC 1-5/8" (40 mm)

COLD 1-5/8" (41 mm)
GAS 5" (127 mm)

HOT 4-5/8" (116 mm)

20-1/2" (520 mm)

1" (26 mm)

13-3/4" (350 mm)

10" (254 mm)

1-3/4" (45 mm) 1-3/4" (45 mm)

21-1/2" (545 mm)

1-3/8" (36 mm)

4-3/8" (113mm)

19-3/8" (493 mm)

120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

HOT 6" (153 mm)

COLD 6" (153 mm)

2-1/4" (58 mm)

3-5/8"(93 mm)

10" (256 mm)

1-7/8" (47 mm)

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

4” Category III Vent

Gas convertible from natural gas to
propane using
the included conversion kit

Flow Rate up to 6.6 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Dimensions

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 140,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

4-3/8" (113mm)

110U: Flow Rate vs. Temperature Rise

9.0

8.0

7.0

6.0

5.0

4.0

3.0

Flow rate (gpm)

2.0

1.0

0

Temperature rise (°F)

2-1/4" (58 mm)

19-3/8" (493 mm)

1" (26 mm)
120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

COLD 6" (153 mm)
HOT 6" (153 mm)
10" (256 mm)

110U: Pressure Loss

100

90

80

70

60

50

40

Pressure Loss (psi)

30

20

10

0

Flow Rate (gpm)

220

200

180

160

140

120

100

80

60

40

20

0

Head (ft)

24

310U SERIES

The 310U features a max flow rate of 8.0 gpm providing enough hot water to run three
showers at the same time. Indoor models include an integrated temperature controller. A remote
control is included as a standard for outdoor models. Complies with SCAQMD Rule 1146.2
and other air quality management districts with similar NOx Emission requirements of 14 ng/J
or 20 PPM.

TK-310U-ETK-310U-I

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-310U-I Natural 15,000 190,000 4.0 10.5 0.82
TK-310U-E Natural 15,000 190,000 4.0 10.5 0.82

Model Number*

TK-310U-I 8 3/4" NPT 3/4” NPT 12 12 3 4 39

TK-310U-E 8 3/4" NPT 3/4” NPT 36 12 3 24 39

*Units are field convertible from natural gas to propane with supplied conversion kit.
**For propane, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

310U
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 140°F (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

79 W / 0.99 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

2 W / 0.06 A
(Standby)

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

96 W / 0.82 A
(Freeze-Protection)

Approx

Shipping

Weight (lbs)

UEF

25

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

120 VAC 1-5/8" (40 mm)

COLD 1-5/8" (41 mm)
GAS 5" (127 mm)

HOT 4-5/8" (116 mm)

20-1/2" (520 mm)

1" (26 mm)

13-3/4" (350 mm)

10" (254 mm)

1-3/4" (45 mm) 1-3/4" (45 mm)

21-1/2" (545 mm)

1-3/8" (36 mm)

4-3/8" (113mm)

19-3/8" (493 mm)

120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

HOT 6" (153 mm)

COLD 6" (153 mm)

2-1/4" (58 mm)

3-5/8"(93 mm)

10" (256 mm)

1-7/8" (47 mm)

310U: Flow Rate vs. Temperature Rise

310U: Pressure Loss

8.0 10.06.0402.00.0

Head (ft)

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

4” Category III Vent

Gas convertible from natural gas to
propane using
the included conversion kit

Flow Rate up to 8 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Dimensions

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 190,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

4-3/8" (113mm)

310U: Flow Rate vs. Temperature Rise

9.0

8.0

7.0

6.0

5.0

4.0

3.0

Flow rate (gpm)

2.0

1.0

0

Temperature rise (°F)

100806040200.0

100

90

80

70

60

50

40

Pressure Loss (psi)

30

20

10

0

2-1/4" (58 mm)

310U: Pressure Loss

Flow Rate (gpm)

19-3/8" (493 mm)

1" (26 mm)
120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

COLD 6" (153 mm)
HOT 6" (153 mm)
10" (256 mm)

220

200

180

160

140

120

100

80

60

40

20

0

Head (ft)

26

510U SERIES

The 510U series is well suited for residential/commercial applications such as small restaurants
and beauty salons. Indoor models include an integrated temperature controller. A remote control
is included as a standard feature for outdoor models. Utilizing commercial-grade copper alloy
for the heat exchanger tubing, the D3U series is also suitable for heavier-residential usages such
as combination space heating and domestic recirculation systems.

TK-510U-ETK-510U-I

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-510U-I Natural 15,000 199,000 4.0 10.5 0.82
TK-510U-E Natural 15,000 199,000 4.0 10.5 0.81

Model Number*

TK-510U-I 10 3/4" NPT 3/4” NPT 12 12 3 4 40
TK-510U-E 10 3/4" NPT 3/4” NPT 36 12 3 24 40

*Units are field convertible from natural gas to propane with supplied conversion kit.
**For propane, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.

510U
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120°F (default) 140°F

With100209924 remote (max. distance 400’ from heater, non-polarized 120 gauge wiring.)

100°F to 160°F (13 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

82 W / 1.02 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

3 W / 0.07 A
(Standby)

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

97 W / 0.82 A
(Freeze-Protection)

Approx

Shipping

Weight (lbs)

UEF

27

ANSI Z21.10.3 • CSA 4.3

NON-CONDENSING

Specifications

510U: Flow Rate vs. Temperature Rise

510U: Pressure Loss

Head (ft)

120 VAC 1-5/8" (40 mm)

COLD 1-5/8" (41 mm)
GAS 5" (127 mm)

HOT 4-5/8" (116 mm)

20-1/2" (520 mm)

1" (26 mm)

13-3/4" (350 mm)

10" (254 mm)

1-3/4" (45 mm) 1-3/4" (45 mm)

21-1/2" (545 mm)

1-3/8" (36 mm)

4-3/8" (113mm)

19-3/8" (493 mm)

120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

HOT 6" (153 mm)

COLD 6" (153 mm)

2-1/4" (58 mm)

3-5/8"(93 mm)

10" (256 mm)

1-7/8" (47 mm)

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

4” Category III Vent

Gas convertible from natural gas to
propane using
the included conversion kit

Flow Rate up to 10 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Easy-Link up to 4 heaters or connect up to
20 heaters with a Multi-Unit Controller

Dimensions

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 199,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

4-3/8" (113mm)

510U: Flow Rate vs. Temperature Rise

12
11

10

9

8
7
6
5
4

Flow rate (gpm)

3

2
1
0

Temperature rise (°F)

Set Temperature 130°F (55°C) or higher, maximum flow rate is limited to 8.0 gpm.

Set temperature: 125°F (52°C) or lower

Set temperature: 130°F (55°C) or higher

140120100806040200

510U: Pressure Loss

100

90

80

70

60

50

40

Pressure Loss (psi)

30

20

10

0

Flow Rate (gpm)

2-1/4" (58 mm)

19-3/8" (493 mm)

1" (26 mm)
120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

COLD 6" (153 mm)
HOT 6" (153 mm)
10" (256 mm)

8.0 10.06.0402.00.0

Set temperature: 125°F (52°C) or lower
Set temperature: 130°F (55°C) or higher

Set Temperature 125°F (52°C) or higher, maximum flow rate is limited to 8.0 gpm.

220

200

180

160

140

120

100

80

60

40

20

0

Head (ft)

28

H3M SERIES

The H3M Series is a high efficiency, ultra-low NOx condensing model with up to 0.91 Uniform
Energy Factor, allowing for the use of 3”or 4” PVC venting or Category IV stainless steel. Indoor
models have an integrated temperature controller and outdoor models include a remote control
as a standard feature.

T-H3M-DV

T-H3M-OS

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-H3M-DV-N Natural 15,000 120,000 4.0 10.5 0.90
T-H3M-OS-N Natural 15,000 120,000 4.0 10.5 0.91

Model Number*

T-H3M-DV-N 6.6 3/4" NPT 1/2" NPT 12 12 3 4 54
T-H3M-OS-N 6.6 3/4" NPT 1/2" NPT 36 12 3 24 52

*For propane models, change “N” to “P”
**For propane models, minimum fire is 13,000 BTU/H, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is

14.0 in. W.C.

H3M
Temperature
Settings

Electric 120 V

Maximum

GPM

Dipswitches 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 120 gauge wiring.)

100°F to 140°F with 5°F intervals (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

54 W / 0.7 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

3 W / 0.05 A
(Standby)

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

224 W / 2 A (Freeze-Protection)

UEF

Approx

Shipping

Weight (lbs)

29

ANSI Z21.10.3 • CSA 4.3

CONDENSING

Specifications

H3M: Flow Rate vs. Temperature Rise

H3M: Pressure Loss

Side viewFront view

10-5/16" (262.2mm)

10-13/16" (274.6mm)

6" (152.1mm)

2-9/16" (64.8mm)

2-3/4" (70.2mm)

Condensate drain port 3-1/4" (82.1mm)
Gas 4-1/8" (105.4mm)
Hot 6-1/2" (164.6mm)

Cold 7" (178.5mm)
120VAC 7-3/4" (196.5mm)

1" (25.5mm)

INDOOR MODEL

Side viewFront view

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

Flow Rate up to 6.6 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 120,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

13-7/8" (352mm)

10" (254mm)

6-1/4" (158.5mm)

4" (102mm)4" (102mm)

58.4

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

10-13/16" (274.6mm)

10-5/16" (262.2mm)

6" (152.1mm)

2-3/4" (70.2mm)

2-9/16" (64.8mm)

5-1/16" (129.1mm)

H3M: Flow Rate vs. Temperature Rise

10

9

8

7

6

5

4

Flow rate (gpm)

3

2

1

0

0 20

Temperature rise (°F)

Hot 4-3/4" (121.1mm)

Condensate drain port

24" (609.4mm)

22-7/8 (580mm)

Cold 1/2" (13.3mm)

5-3/8" (137mm)
7-1/16" (180mm)

120VAC 3-1/16" (77mm)

Gas 4/1/2" (113.7mm)

40 60 80 100

110

H3M: Pressure Loss

60
55

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

0.0 1.0

Flow Rate (gpm)

2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

1" (25.5mm)

Condensate drain port 3-1/4" (82.1mm)
Gas 4-1/8" (105.4mm)
Hot 6-1/2" (164.6mm)

Cold 7" (178.5mm)
120VAC 7-3/4" (196.5mm)

140

120

100

80

60

Head (ft)

40

20

0

30

H3J SERIES

The H3J series offers high efficiency Ultra-Low NOx condensing technology allowing for the use
of 3” PVC venting and has 0” clearance to combustibles. Indoor models have an integrated
temperature controller and outdoor models include a remote control as a standard feature.

T-H3J-OST-H3J-DV

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-H3J-DV-N Natural 15,000 160,000 4.0 10.5 0.94
T-H3J-OS-N Natural 15,000 160,000 4.0 10.5 0.95

Model Number*

T-H3J-DV-N 6.6 3/4" NPT 3/4" NPT 12 12 3 4 71
T-H3J-OS-N 6.6 3/4" NPT 3/4" NPT 36 12 3 24 69

*For propane models, change “N” to “P”
**For propane models, minimum fire rate is 13,000 BTU/H, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pres­sure is 14.0 in. W.C.

H3J
Temperature
Settings

Electric 120 V

Maximum

GPM

Built In / without remote 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 140°F with 5°F intervals (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

73 W / 0.61 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

Minimum
(in. W.C.)

Clearances (in.)

Top Bottom Side Front

3 W / 0.03 A
(Standby)

174 W / 1.5 A
(Freeze-Protection)

Maximum

(in. W.C.)

UEF

Approx

Shipping

Weight (lbs)

31

ANSI Z21.10.3 • CSA 4.3

CONDENSING

Specifications

22-1/22" (570 mm)

10-3/4" (272mm)

22-1/22" (570 mm)

2-5/8" (68 mm)

Exhaust

Intake

2-5/8" (65 mm)

5-3/4" (147 mm)

11-1/4" (285 mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)

COLD 6-3/4" (172 mm)

Drain port 6" (152 mm)

120 VAC 6-7/8" (174 mm)

H3J: Flow Rate vs. Temperature Rise

120

H3J: Pressure Loss

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

Flow Rate up to 6.6 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 160,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

17-3/4" (450 mm)

4" (102 mm)

∅

Female

7" (180 mm)

6-1/4" (159mm)

4" (101 mm)

4" (102 mm)

∅

Female

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

11-1/4" (285 mm)

5-3/4" (147 mm)

HOT 4-3/4" (120 mm)

H3J: Flow Rate vs. Temperature Rise

10

9

8

7

6

5

4

Flow rate (gpm)

3

2

1

0

0 20

Temperature rise (°F)

24-7/8" (631 mm)

23-5/8" (600 mm)

Drain port

6-3/4" (170 mm)

COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
GAS 5-3/4" (147 mm)
Condensate drain port

7-1/2" (189 mm)

40 60 80 100 120

H3J: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

0.0 1.0

Flow Rate (gpm)

2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Intake

2-5/8" (68 mm)

2-5/8" (65 mm)

Exhaust

10-3/4" (272mm)

1/2 (13 mm)

GAS 5-1/8" (131 mm)

HOT 5-1/2" (140 mm)
Drain port 6" (152 mm)
COLD 6-3/4" (172 mm)

120 VAC 6-7/8" (174 mm)

Condensate drain port

7-7/8" (199 mm)

100

80

60

40

20

0

Head (ft)

32

H3S SERIES

The H3S series offers high efficiency Ultra-Low NOx condensing technology allowing for the
use of 3” PVC venting and has 0” clearance to combustibles. Indoor models are certified up
to 10,100 ft. altitude. Indoor models have an integrated temperature controller and outdoor
models include a remote control as a standard feature.

T-H3S-DV T-H3S-OS

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-H3S-DV-N Natural 15,000 180,000 4.0 10.5 0.95
T-H3S-OS-N Natural 15,000 180,000 4.0 10.5 0.94

Model Number*

T-H3S-DV-N 8 3/4" NPT 3/4" NPT 12 12 3 4 71
T-H3S-OS-N 8 3/4" NPT 3/4" NPT 36 12 3 24 69

*For propane models, change “N” to “P”
**For propane models, minimum fire rate is 13,000 BTU/H, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pres­sure is 14.0 in. W.C.

H3S
Temperature
Settings

Electric 120 V

Maximum

GPM

Built In / without remote 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 140°F with 5°F intervals (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

78 W / 0.65 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

3 W / 0.03 A
(Standby)

174 W / 1.5 A
(Freeze-Protection)

Maximum

(in. W.C.)

UEF

Approx

Shipping

Weight (lbs)

33

ANSI Z21.10.3 • CSA 4.3

CONDENSING

Specifications

10-3/4" (272mm)

22-1/22" (570 mm)

2-5/8" (68 mm)

Exhaust

Intake

2-5/8" (65 mm)

5-3/4" (147 mm)

11-1/4" (285 mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)

COLD 6-3/4" (172 mm)

Condensate drain port

Drain port 6" (152 mm)

120 VAC 6-7/8" (174 mm)

H3S: Flow Rate vs. Temperature Rise

H3S: Pressure Loss

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

Flow Rate up to 8 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 180,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

17-3/4" (450 mm)

4" (102 mm)

∅

Female

7" (180 mm)

6-1/4" (159mm)

4" (101 mm)

4" (102 mm)

∅

Female

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

11-1/4" (285 mm)

5-3/4" (147 mm)

10.0

9.0

8.0

7.0

6.0

5.0

4.0

Flow rate (gpm)

3.0

2.0

1.0

0.0
0 20

24-7/8" (631 mm)

23-5/8" (600 mm)

HOT 4-3/4" (120 mm)

Drain port

6-3/4" (170 mm)

COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
GAS 5-3/4" (147 mm)
Condensate drain port

7-1/2" (189 mm)

H3S: Flow Rate vs. Temperature Rise

40 60 80 100 120

Temperature rise (°F)

22-1/22" (570 mm)

H3S: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

0.0 1.0

2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Flow Rate (gpm)

Intake

2-5/8" (68 mm)

2-5/8" (65 mm)

Exhaust

10-3/4" (272mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)
Drain port 6" (152 mm)
COLD 6-3/4" (172 mm)
120 VAC 6-7/8" (174 mm)
Condensate drain port

7-7/8" (199 mm)

120

100

80

60

40

20

0

Head (ft)

34

H3 SERIES

Utilizing commercial-grade copper alloy for the heat exchanger tubing, the H3 is suitable
for heavier residential usages such as combination space heating and domestic recirculation
systems. Indoor models have an integrated temperature controller and outdoor models include
a remote control as a standard feature. Indoor models are certified up to 10,100 ft. altitude.
Complies with Ultra-Low NOx regulations.

T-H3-DV T-H3-OS

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

T-H3-DV-N Natural 15,000 199,000 4.0 10.5 0.93
T-H3-OS-N Natural 15,000 199,000 4.0 10.5 0.95

Model Number*

T-H3-DV-N 10 3/4" NPT 3/4" NPT 12 12 3 4 71

T-H3-OS-N 10 3/4" NPT 3/4" NPT 36 12 3 24 69

*For propane models, change “N” to “P”
**For propane models, minimum fire rate is 13,000 BTU/H, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pres­sure is 14.0 in. W.C.

H3
Temperature
Settings

Electric 120 V

Maximum

GPM

Built In / without remote 120°F (default) 140°F

With 100209924 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 160 °F with 5°F intervals (13 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

89 W / 0.74 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

Minimum

(in. W.C.)

Clearances (in.)

Top Bottom Side Front

4 W / 0.04 A
(Standby)

175 W / 1.5 A
(Freeze-Protection)

Maximum

(in. W.C.)

UEF

Approx

Shipping

Weight (lbs)

35

ANSI Z21.10.3 • CSA 4.3

CONDENSING

Specifications

10-3/4" (272mm)

22-1/22" (570 mm)

2-5/8" (68 mm)

Exhaust

Intake

2-5/8" (65 mm)

5-3/4" (147 mm)

11-1/4" (285 mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)

COLD 6-3/4" (172 mm)

Condensate drain port

Drain port 6" (152 mm)

120 VAC 6-7/8" (174 mm)

H3: Flow Rate vs. Temperature Rise

H3: Pressure Loss

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

Flow Rate up to 10 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 199,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

17-3/4" (450 mm)

4" (102 mm)

∅

Female

7" (180 mm)

6-1/4" (159mm)

4" (101 mm)

4" (102 mm)

∅

Female

Easy-Link up to 4 heaters or connect
up to 20 heaters with a Multi-Unit
Controller

Warranty

• 15-year limited warranty on heat exchanger in
residential applications.

• 5-year limited warranty on heat exchanger in
commercial applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

11-1/4" (285 mm)

5-3/4" (147 mm)

HOT 4-3/4" (120 mm)

H3: Flow Rate vs. Temperature Rise

11

10

9

8

7

6

5

Flow rate (gpm)

4

3

2

1

0

20 40

Temperature rise (°F)

24-7/8" (631 mm)

23-5/8" (600 mm)

Drain port

6-3/4" (170 mm)

COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
GAS 5-3/4" (147 mm)
Condensate drain port

7-1/2" (189 mm)

60 80 100 120 140

Set temperature: 125°F or lower
Set temperature: 130°F or higher

Pressure Loss (psi)

Intake

2-5/8" (68 mm)

2-5/8" (65 mm)

Exhaust

22-1/22" (570 mm)

10-3/4" (272mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)
Drain port 6" (152 mm)
COLD 6-3/4" (172 mm)
120 VAC 6-7/8" (174 mm)
Condensate drain port

7-7/8" (199 mm)

H3: Pressure Loss

50

45

40

35

30

25

20

15

10

5

0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Flow Rate (gpm)

Set temperature: 125°F or lower
Set temperature: 130°F or higher

100

80

60

40

Head (ft)

20

0

36

540P SERIES

The 540P Series integrates a recirculation pump to provide instant hot water in residential
applications with dedicated recirculation lines. The pump is easily controlled with a simple user
interface and multiple pump settings allow you to customize pump operation to meet your needs
while maximizing heater efficiency. Indoor models have an integrated temperature and pump
controller and outdoor models include a remote control as a standard feature.

TK-540P-NIH TK-540P-NEH

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TK-540P-NIH Natural 15,000 199,000 4.0 10.5 0.93
TK-540P-NEH Natural 15,000 199,000 4.0 10.5 0.95

Model Number*

TK-540P-NIH 10 3/4" NPT 3/4" NPT 12 12 3 4 71

TK-540P-NEH 10 3/4" NPT 3/4" NPT 36 12 3 24 70

*For propane models, change “N” to “P”
**For propane models, minimum fire is 13,000 BTU/H, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is

14.0 in. W.C.

540P
Temperature
Settings

Electric 120 V

Maximum

GPM

Built In / without remote 120°F (default) 140°F

With 100276687 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 140°F with 5°F intervals (9 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

1.09 W / 1.34 A
(Operation)

Connection

Maximum

(BTU/H)

Gas

5 W / 0.1 A
(Standby)

Minimum
(in. W.C.)

Clearances (in.)

Top Bottom Side Front

Maximum

(in. W.C.)

192 W / 1.6 A
(Freeze-Protection)

UEF

Approx

Shipping

Weight (lbs)

37

ANSI Z21.10.3 • CSA 4.3

CONDENSING

Specifications

540P: Flow Rate vs. Temperature Rise

540P: Pressure Loss

Set temperature: 130°F or higher

Drain port 4-7/8" (124 mm)

HOT 6-3/4" (171 mm)

RETURN 3-1/8" (79 mm)

11-1/4" (285 mm)

5-3/4" (147 mm)

Exhaust 2-5/8" (65 mm)

Intake 2-5/8" (68 mm)

RETURN 4-5/8" (117 mm)
GAS 5-1/8" (131 mm)

HOT 6-1/2" (164 mm)
COLD 6-3/4" (172 mm)

1/2 (13 mm)

Drain port 6-1/4" (159 mm)

120 VAC 3-7/8" (174 mm)

540P Indoor (AT-H3P-DV)

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

Integrated recirculation pump

Flow Rate up to 10 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 199,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

17-3/4" (450 mm)

15" (381 mm)

Φ 4" (102 mm)

7" (180 mm)

6-1/4" (159 mm)

Φ 4" (102 mm)

FemaleFemale

Easy-Link with up to 3 other T-H3 heaters

Warranty

• 15-year limited warranty on heat exchanger in residential
applications.

• 5-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

11-1/4" (285 mm)

5-3/4" (147 mm)

540P: Flow Rate vs. Temperature Rise

11

10

9

8

7

6

5

Flow rate (gpm)

4

3

2

1

0

0

Temperature rise (°F)

24-7/8" (631 mm)

23-5/8" (600 mm)

20 40

COLD 5/8" (17 mm)

120 VAC 3" (77 mm)

GAS 5-3/4" (147 mm)

Condensate drain port

7-1/2" (189 mm)

60 80 100

Set temperature: 125°F or lower
Set temperature: 130°F or higher

110

Intake 2-5/8" (68 mm)

Exhaust 2-5/8" (65 mm)

1/2 (13 mm)
RETURN 4-5/8" (117 mm)
GAS 5-1/8" (131 mm)
Drain port 6-1/4" (159 mm)
HOT 6-1/2" (164 mm)
COLD 6-3/4" (172 mm)
120 VAC 3-7/8" (174 mm)
Condensate drain port
7-7/8" (199 mm)

540P: Pressure Loss

50

45

40

35

30

25

20

Pressure Loss (psi)

15

10

5

0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Flow Rate (gpm)

Set temperature: 125°F or lower

100

80

60

40

Head (ft)

20

0

38

M50 SERIES

The M50 Series, specifically designed for heavy-duty applications, is the largest
Takagi tankless heater yet and the most powerful (14.5 GPM max) in the tankless industry.
The M50 Series is suitable for commercial applications (hotels, restaurants, government,
convalescent homes, etc.) that require high demand and the most durable of heaters. Along
with commercial-grade copper alloy, the M50 Series is the only commercial unit in the industry
that offers a “dual-combustion system,” providing redundancy for added reliability.

T-M50-N

Specifications

Model

Number*

T-M50-N Natural 15,000 380,000 4.0 10.5 80%

Model

Number*

T-M50-N 1" NPT 1" NPT 12*** 12 2 4*** 113

†For ASME version, use model number T-M50-ASME-N
*For propane models, change N to P
**For propane models, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pressure is 14.0 in. W.C.
***If installed outdoors, top clearance is 36” and front clearance is 24”

M50
Temperature
Settings

Electric

Type

Connections Clearances (in.)

Water Gas Top Bottom Side Front

Built In / without remote 110°F, 115°F, 120°F (default), 135°F, 145°F, 155°F, 165°F, 185°F

With 100112155 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 175°F with 5°F intervals (16 options), 120°F Default Factory Setting

120
VAC

Gas Consumption Input Inlet Gas Pressure**

Minimum

(BTU/H)

175 W / 1.48 A
(Operation)

Maximum

(BTU/H)

16 W / 0.13 A
(Standby)

Minimum

(in. W.C.)

271 W / 2.26 A
(Freeze-Protection)

Maximum

(in. W.C.)

Thermal

Efficiency

Approx

Shipping

Weight (lbs)

39

ANSI Z21.10.3 • CSA 4.3

COMMERCIAL

Specifications

M50: Flow Rate vs. Temperature Rise M50: Pressure Loss

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Low NOx Emissions

Flow Rate up to 14.5 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 380,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

Easy-Link up to 4 heaters or connect up to
10 heaters with a Multi-Unit Controller

Warranty

• 6-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

M50: Flow Rate vs. Temperature Rise

16

14

12

10

8

6

Flow rate (gpm)

4

2

0

25 45 65 85 105 125 145

Temperature rise (°F)

Set temperature: 145°F or lower
Set temperature: 150°F or higher

M50: Pressure Loss

25

20

15

10

Pressure Loss (psi)

5

0

Flow Rate (gpm)

Set temperature: 145°F or lower
Set temperature: 150°F or higher

50

40

30

20

Head (ft)

10

0

16.014.012.010.08.06.04.02.00.0

40

CT-199 SERIES

The CT-199 is well suited for commercial applications such as small restaurants and beauty
salons. Complies with Ultra-Low NOx regulations. Utilizing commercial-grade copper alloy
for the heat exchanger tubing, the H3C is also suitable for combination space heating and
domestic recirculation systems. Indoor models have an integrated temperature controller and
outdoor models include a remote control as a standard feature. Indoor models are certified up
to 10,100 ft. altitude.

TCT-199I TCT-199O

Specifications

Gas Consumption Input Inlet Gas Pressure**

Model Number* Type

TCT-199I-N Natural 15,000 199,000 4.0 10.5 96% 0.93

TCT-199O-N Natural 15,000 199,000 4.0 10.5 96% 0.95

Model Number*

TCT-199I-N 10 3/4" NPT 3/4" NPT 12 12 3 4 71

TCT-199O-N 10 3/4" NPT 3/4" NPT 36 12 3 24 69

*For propane models, change “N” to “P”
**For propane models, minimum fire rate is 13,000 BTU/H, minimum inlet gas pressure is 8.0 in. W.C. and maximum inlet gas pres­sure is 14.0 in. W.C.

CT-199
Temperature
Settings

Electric 120 V

Maximum

GPM

Built In / without remote 120°F (default) 140°F

With 100112572 remote (max. distance 400’ from heater, non-polarized 20 gauge wiring.)

100°F to 185°F with 5°F intervals (16 options), 120°F Default Factory Setting

Minimum

(BTU/H)

Hot/Cold

Connections

89 W / 0.74 A
(Operation)

Maximum

(BTU/H)

Gas

Connection

4 W / 0.04 A
(Standby)

Minimum
(in. W.C.)

Top Bottom Side Front

Maximum

(in. W.C.)

Clearances (in.)

175 W / 1.5 A
(Freeze-Protection)

Thermal

Efficiency

UEF

Approx

Shipping

Weight (lbs)

41

ANSI Z21.10.3 • CSA 4.3

COMMERCIAL

Specifications

10-3/4" (272mm)

22-1/22" (570 mm)

2-5/8" (68 mm)

Exhaust

Intake

2-5/8" (65 mm)

5-3/4" (147 mm)

11-1/4" (285 mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)

COLD 6-3/4" (172 mm)

Condensate drain port

Drain port 6" (152 mm)

120 VAC 6-7/8" (174 mm)

CT-199: Flow Rate vs. Temperature Rise

CT-199: Pressure Loss

Indoor and Outdoor Installation Options

Power Vent or Power Direct Vent Design

Ultra-Low NOx Emissions

Flow Rate up to 10 GPM

• Values based on factory testing. 0.4 GPM required for
continuous fire after initial ignition

Water Pressure: 15-150 psi

• Pressure Only Relief Valve Requires (Min 199,000 btu/h,
150 psi).

• 40 psi or above recommended for max. flow

Dimensions

17-3/4" (450 mm)

4" (102 mm)

∅

Female

7" (180 mm)

6-1/4" (159mm)

4" (101 mm)

4" (102 mm)

∅

Female

Easy-Link up to 4 heaters or connect up to
20 heaters with a Multi-Unit Controller

Create a Multi-Unit system with the
100112691 controller 96% thermal
efficiency

Warranty

• 6-year limited warranty on heat exchanger in commercial
applications.

• 5-year warranty on all parts.

• Refer to takagi.com for further warranty details

11-1/4" (285 mm)

5-3/4" (147 mm)

HOT 4-3/4" (120 mm)

CT-199: Flow Rate vs. Temperature Rise

11

10

9

8

7

6

5

Flow rate (gpm)

4

3

2

1

0

20 40

Temperature rise (°F)

24-7/8" (631 mm)

23-5/8" (600 mm)

Drain port

6-3/4" (170 mm)

COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
GAS 5-3/4" (147 mm)
Condensate drain port

7-1/2" (189 mm)

60 80 100 120 140

Set temperature: 125°F or lower
Set temperature: 130°F or higher

Pressure Loss (psi)

Intake

2-5/8" (68 mm)

2-5/8" (65 mm)

Exhaust

22-1/22" (570 mm)

10-3/4" (272mm)

1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)
Drain port 6" (152 mm)
COLD 6-3/4" (172 mm)
120 VAC 6-7/8" (174 mm)
Condensate drain port

7-7/8" (199 mm)

CT-199: Pressure Loss

50

45

40

35

30

25

20

15

10

5

0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Flow Rate (gpm)

Set temperature: 125°F or lower
Set temperature: 130°F or higher

100

80

60

40

20

0

Head (ft)

42

COMMERCIAL TANKLESS RACK SYSTEM

Commercial tankless rack systems allow the power of tankless
technology to be customized with unprecedented flexibility.
Takagi offers wall mount, free standing and back-to-back
configurations with easy options to integrate storage when
needed. For jobs that require more than six units, custom
solutions are available.

Installation is easier than ever as the rack systems are
constructed from a light weight frame and just three connections
for hot water, cold water and gas.

Commercial rack systems are expandable with up to
1,194,000 BTU on a single system. The rack system
is designed so that individual units can be isolated for
maintenance without shutting down the entire rack to provide
non-stop operation.

43

MULTI- UNIT SYSTEMS

Takagi tankless water heaters have the capability to
link multiple heaters together to act as a system. The
primary heater is rotated to ensure even operation of
all heaters. The D2,510U/C, H3, CT-199, and M50
series models can Easy-Link up to four units using included
communication cables.

For even larger applications the 510U (series 200),
510C, H3, CT-199, and M50 series models also feature
the Multi-Unit System, allowing a greater number of units
to work together as an integrated system using a Multi­Unit System Controller. The Multi-Unit System can control
up to twenty 510U (series 200), 510C, H3, and CT-199
or up to ten M50 heaters.

Unit Comparison

D2 Series 510U/C Series H3/CT-199 Series M50 Series

Easy-Link (No Controller Necessary)
Maximum input (BTU/h)

Up to 4 units Up to 4 units Up to 4 units Up to 4 units

796,000 796,000 796,000 1,520,000

Multi-Unit*

Maximum input (BTU/h)
*Requires Multi-Unit Controller: 100112691

N/A Up to 20 units Up to 20 units Up to 10 units

N/A 3,980,000 3,980,000 3,800,000

COMMON VENTING

The Takagi common venting system utilizes fewer
unique components so you can design your venting
based on project requirements.

• More design flexibility

• Fewer wall penetrations

• Able to use schedule 40 PVC on intake and
exhaust

• Heaters don’t de-rate when common vented

• Design doesn’t override redundancy benefits

44

APPLICATION DIAGRAMS

Takagi tankless water heaters can be used in a wide variety of applications. Whether used in recirculation systems, in
conjunction with storage tanks or with heating applications, our commercial units are built to provide continuous hot water
when sized appropriately for your home’s needs.

*Local codes dictate proper compliance.

Legend

Pump

Shut Off /
Isolation
Valves

Pressure
Relief
Valve

Air
Vent

Aquastat

Check
Valve

Full Port
Ball Valve

Basic Installation

(excluding 540P)

Hot Water Return

Hot Water to Fixtures

Expansion Tank

1. Recirculation pump shall be sized for 2-4 gpm per activated heater (4-8 gpm for T-M50)

2. Recirculation pump shall be controlled by an aquastat. The minimum suggested differential should be 10°F

3. For installations without recirculation, remove the check valves, pump, and aquastat.

Gas Supply
Cold Water Supply

540P Basic Installation

All application diagrams shown are concept drawings only. These diagrams are only to be used as basic guides. It is up to the application designer to properly design the
plumbing layout and correctly size all components within an application (pumps, piping, storage tanks, water heaters, etc.). All national and local codes must be followed and will
dictate proper compliance.

45

MULTIPLE UNITS

Multiple Units with Easy-Link

Gas
Hot
Water to
Fixtures

1. Recirculation pump shall be sized for 2-4 gpm per activated heater (4-8 gpm for T-M50)

2. Recirculation pump shall be controlled by an aquastat. The minimum suggested differential should be 10°F

3. The automatic air should be installed at the highest location of the system in accordance with the manufacturer’s instructions.

Supply

Multiple Unit with the Multi-Unit Controller

Hot Water
Return

Cold
Water
Supply

Expansion Tank

Gas Supply

Hot
Water to
Fixtures

Expansion Tank

1. Recirculation pump shall be sized for 2-4 gpm per activated heater (4-8 gpm for T-M50)

2. Recirculation pump shall be controlled by an aquastat. The minimum suggested differential should be 10°F

3. The automatic air should be installed at the highest location of the system in accordance with the manufacturer’s instructions.

All application diagrams shown are concept drawings only. These diagrams are only to be used as basic guides. It is up to the application designer to properly design the
plumbing layout and correctly size all components within an application (pumps, piping, storage tanks, water heaters, etc.). All national and local codes must be followed and will
dictate proper compliance.

Hot Water
Return

Cold
Water
Supply

46

MULTI-UNITS

Multiple Unit with Storage

Hot Water to Fixtures

Gas
Supply

P-1

1. Tank circulation pump, P-1, should be controlled by tank aquastat, T-1.

2. Tank aquastat, T-1, should be set 20°F below water heater set temperature.

3. Pump P-1 should be sized to provide flow necessary to heat the storage tank.
Refer to the water heater’s spec sheet for pressure drop curves.

T-1

Expansion
Tank

Hot Water

T-2P-2

Return

Cold Water
Supply

All application diagrams shown are concept drawings only. These diagrams are only to be used as basic guides. It is up to the application designer to properly design the
plumbing layout and correctly size all components within an application (pumps, piping, storage tanks, water heaters, etc.). All national and local codes must be followed and will
dictate proper compliance.

47

SOLAR TANKLESS BACK UP

COLLECTOR SENSOR

TANKLESS

WATER HEATER

FIELD SUPPLIED PUMP

COLD

WATER

INLET

CH

GAS

SUPPLY

HOT WATER RETURN

TANKLESS SUPPLY LINE

TEMPERED

HOT WATER

T

AQUASTAT

STORAGE TANK

SOLAR

COLLECTOR

TANK SENSOR

SOLAR

CONTROL

NOTES:

1. Ensure field supplied tank aquastat is in top 1/3 section of the tank.

2. Set tank aquastat 10°F lower than tankless unit set point.

3. Ensure the hot water return from the tankless unit is connected to the hot water outlet from the solar tank as shown in the drawing.

4. The supply line to the tankless unit may be made at the element fitting (after element is removed) with a 1”-11-1/2 NPSH fitting and gasket.

5. Field supplied pump must provide > 3 GPM flow through tankless backup loop - contact pump manufacturer for sizing assistance.

All application diagrams shown are concept drawings only. These diagrams are only to be used as basic guides. It is up to the application designer to properly design the
plumbing layout and correctly size all components within an application (pumps, piping, storage tanks, water heaters, etc.). All national and local codes must be followed and will
dictate proper compliance.

48

VENTING DIAGRAMS (EXAMPLES)

4” Sidewall Termination

(Please check the wall thickness
for proper installation)

2

1

3

Models KJr2/110U, K4/310U, D2/510U

4” Combustible Sidewall Termination

1 100112419 4" Sidewall Hood Terminator 1

Kit Part

Number:

4

100112726

2 100112732 4" Wall Thimble (4.0"-7.0") 1

3 100112400 4" 90 degree Elbow 1

4 100112399 4" Female-Female Adaptor 1

Qty.

1

2

3

Models KJr2/110U, K4/310U, D2/510U

4" Non-Combustible Sidewall Termination

Kit Part

Number:

100112767

49

1 100112419 4" Sidewall Hood Terminator 1

2 100112400 4" 90 degree Elbow 1

3 100112399 4" Female-Female Adaptor 1

Qty.

4” Sidewall Termination

(With Condensate Trap)

(Please check the wall thickness
for proper installation)

3

1

Models KJr2/110U, K4/310U, D2/510U

4” Combustible Sidewall Termination (With Condensate Trap)

4

2

Kit Part

Number:

100112775

1 100112419 4" Sidewall Hood Terminator 1

2 100112732 4” Wall Thimble (4.0”-7.0”) 1

3 100112400 4” 90 Degree Elbow 1

4 100112549 4” Universal Appliance Adaptor 1

Qty.

1

2

3

Models KJr2/110U, K4/310U, D2/510U

4" Non-Combustible Sidewall Termination
(With Condensate Trap)

Kit

Part Number:

100112776

1 100112419 4" Sidewall Hood Terminator 1

2 100112400 4" 90 degree Elbow 1

3 100112549 4" Universal Appliance Adaptor 1

Qty.

50

1

2

4

3

DIRECT VENT, CONCENTRIC SIDEWALL
TERMINATION

KJr2, K4, D2 Models

M50 Model

3

4

Models KJr2, K4, D2

5-10” Sidewall Thickness Direct Vent,
Concentric Termination

1 100112550 Concentric Intake/Exhaust Kit 1

Kit Part

Number:

100112421

12-18” Sidewall Thickness Direct Vent, Concentric Termination

Kit Part

Number:

100112420

1

2 100112549 Universal Appliance Adaptor 1

3 NA 3” Aluminum Flex 1

4 100112184 Direct Vent Conversion Kit 1

1 100112551 Concentric Intake/Exhaust Kit 1

2 100112549 Universal Appliance Adaptor 1

3 NA 3” Aluminum Flex 1

4 100112184 Direct Vent Conversion Kit 1

Model M50

5-10” Sidewall Thickness Direct Vent, Concentric Termination

2

Kit Part

Number:

100112606

12-18” Sidewall Thickness Direct Vent, Concentric Termination

Kit Part

Number:

100112601

1 100112604 Concentric Intake/Exhaust Kit 1

2 100112597 Universal Appliance Adapter 1

3 NA 5” Aluminum Flex 1

4 100112186 Direct Vent Conversion Kit 1

1 100112605 Concentric Intake/Exhaust Kit 1

2 100112597 Universal Appliance Adaptor 1

3 NA 5” Aluminum Flex 1

4 100112186 Direct Vent Conversion Kit 1

Qty.

Qty.

Qty.

Qty.

51

4” Rooftop Termination

1

3

2

4

Models KJr2/110U, K4/310U, D2/510U

4” Flat Roof Termination

1 100112548 4” Extreme Weather Rain Cap 1

2 100112410 4” Storm Collar 1

3 100112412 4” Flat Roof Flashing 1

Kit Part

Number:

100112727

7

4 100112408 4” Vertical Firestop 1

5 100112400 4” 90 degree Elbow 2

6 100112549

Refer to Accessories

7

Chart

4” Universal Appliance

Adaptor

Straight Pipe TBD

Qty.

1

1

2

3

7

5

6

Models KJr2/110U, K4/310U, D2/510U

4” Angled Roof Termination

1 100112548 4” Extreme Weather Rain Cap 1

2 100112410 4” Storm Collar 1

Kit Part

Number:

100112728

3 100112411 4” Angeled Roof Flashing 1

4 100112408 4” Vertical Firestop 1

5 100112400 4” 90 degree Elbow 2

6 100112549 4” Universal Appliance Adaptor 1

Refer to Accessories

7

Chart

Straight Pipe TBD

7

4

7

5

6

Qty.

52

5” Sidewall Termination

2

3

4

Model M50

5" Combustible Sidewall Termination

1 100112594 5" Sidewall Hood Terminator 1

1

Kit Part

Number:

100112729

2 100112734 5" Wall Thimble (4.0"-7.0") 1

3 100112587 5" 90 degree Elbow 1

4 100112599 5" Female-Female Adaptor 1

Qty.

Model M50

5" Non-Combustible Sidewall Termination

Kit

Part Number:

100112768

1 100112594 5" Sidewall Hood Terminator 1

2 100112587 5" 90 degree Elbow 1

3 100112599 5" Female-Female Adaptor 1

1

2

3

Qty.

53

5” Sidewall Termination

(With Condensate Traps)

2

Model M50

3

4

1

5" Combustible Sidewall Termination (With Condensate Trap)

1 100112594 5" Sidewall Hood Terminator 1

Kit

Part Number:

100112777

2 100112734 5" Wall Thimble (4.0"-7.0") 1

3 100112587 5" 90 degree Elbow 1

4 100112597 5" Universal Appliance Adaptor 1

Qty.

1

2

Model M50

5" Non-Combustible Sidewall Termination
(With Condensate Trap)

5" Sidewall Hood

Terminator

5" 90 degree

Elbow

5" Universal Appli-

ance Adaptor

Kit

Part Number:

100112778

1 100112594

2 100112587

3 100112597

3

Qty.

1

1

1

54

5” Rooftop Termination

Model M50

1

7

3

2

5” Flat Roof Termination

1 100112596 5” Extreme Weather Rain Cap 1

2 100112590 5” Storm Collar 1

3 100112592 5” Flat Roof Flashing 1

Kit

Part Number:

100112730

4 100112591 5” Vertical Firestop 1

5 100112587 5” 90 degree Elbow 2

6 100112597

Refer to Accessories

7

Chart

5” Universal Appliance

Adaptor

Straight Pipe TBD

Qty.

1

7

1

4

3

7

2

6

Model M50

5” Angled Roof Termination

1 100112596 5” Extreme Weather Rain Cap 1

2 100112590 5” Storm Collar 1

Kit

Part

Number:

100112731

3 100112593 5” Angled Roof Flashing 1

4 100112591 5” Vertical Firestop 1

5 100112587 5” 90 degree Elbow 2

6 100112597 5” Universal Appliance Adaptor 1

Refer to Accessories

7

Chart

7

5

4

7

Qty.

5

6

Straight Pipe TBD

55

CONCENTRIC VENT SERIES

Horizontal Installa�on

Horizontal Installation

1

Models 110C, 310C, 510C

1 Standard Sidewall Kits*

2 Straight Pipe

3 Elbow

4 Condensate Trap 100266139

5 Condensate Collector 100266140

*This kit includes one 87° elbow

100266115 (11.5")

100266117 (21")

100266133 (10")

100266134 (19.5")

100266135 (39")
100266119 (45°)

100266132 (87°)

Horizontal Installa�on

3

2

4

5

1

56

CONCENTRIC VENT SERIES

Vertical Installation

Ver�cal Installa�on

2

6

Models 110C, 310C, 510C

1 Roof Termination (38") 100266118

100266136

(1/12 to 6/12 pitch)

100266137

2 Tile/Shingle Roof Flashing

1

3 Straight Pipe

4 Pipe Hangers 100266141

5 Elbow

6 Condensate Trap 100266139

7 Condensate Collector 100266140

(8/12 to 16/12 pitch)

100266138

(6/12 to 12/12 pitch)

100266187 (Flat Roof)

100266133 (10")

100266134 (19.5")

100266135 (39")

100266119 (45°)
100266132 (87°)

Ver�cal Installa�on

3

1

6

7

2

3

4

5

6

7

57

VENTING COMPONENTS

Simple Leak-Proof Gasketed Connections – No Sealant Required. High Quality – Category III /IV Stainless Steel.
Versatile – Vertical and Horizontal Terminations. Convenient – Vent Kits Available.
UL Listed. All Connections have Heat-Resistant Rubber Gaskets.

Nova Vent

Part #

STRAIGHT VENT PIPE

100112407 4” Straight pipe - 6” Length

100112406 4” Straight pipe - 12” Length

100112404 4” Straight pipe - 24” Length

100112403 4” Straight pipe - 36” Length

100112402 4” Straight pipe - 48” Length

100112580 5” Straight pipe - 6” Length

100112581 5” Straight pipe - 12” Length

100112582 5” Straight pipe - 24” length

100112583 5” Straight pipe - 36” Length

100112584 5” Straight pipe - 48” Length

ADJUSTABLE VENT PIPE

100112405 4” Adjustable Pipe (7”- 9.9”)

100112585 5” Adjustable Pipe (7”- 9.9”)

ELBOW

100112401 4” 45 Degree Elbow

DESCRIPTION

Nova Vent

Part #

BACKFLOW PREVENTER

100112416

100112598

CONDENSATION

100112414 4” Horizontal Drain Tee

100112588 5” Horizontal Drain Tee

100112413 4” Vertical Drain Tee

100112589 5” Vertical Drain Tee

SUPPORT

100112409 4” Support Strap (1”)

100112600 5” Support Strap (1”)

DESCRIPTION

4” Backflow Preventer & F-F
Adaptor

5” Back-flow Preventer & F-F
Adaptor

DRAIN

100112586 5” 45 Degree Elbow

100112400 4” 90 Degree Elbow

100112587 5” 90 Degree Elbow

ADAPTOR

100112399 4” Female-Female Adaptor

100112599 5” Female-Female Adaptor

100112549

100112597

4” Universal Appliance Adaptor
3-in-1 (F-F adaptor, condensate
drain, & back-flow preventer)

5” Universal Appliance Adaptor
3-in-1 (F-F adaptor, condensate
drain, & back-flow preventer)

WALL THIMBLE

100112732 4” Wall Thimble (4”-7”)

100112733 4” Wall Thimble (5”-10”)

100112734 5” Wall thimble (4”-7”)

100112735 5” Wall thimble (5”-10”)

4” SIDEWALL TERMINATION & THIMBLE KIT

100112424

100112425

Sidewall Vent Terminator (Hood)
and Wall Thimble (4”-7”)

Sidewall Vent Terminator (Hood)
and Wall Thimble (5”-10”)

Note: KJr2/110U, H3M, K4/310U, D2/510U, H3J, H3S, H3 series are compatible with 4” components. M50 series is compatible with 5” components.

58

Nova Vent

Part #

TERMINATION

DESCRIPTION

Nova Vent

Part #

DESCRIPTION

INTAKE HOOD (GALVANIZED)

100112547 4” Termination Tee

100112595 5” Termination Tee

100112419

100112594

4”Exhaust Sidewall Vent
Terminator (Hood)

5”Exhaust Sidewall Vent
Terminator (Hood)

100112415 4” Rain Cap

100112548 4” Extreme Weather Rain Cap

100112596 5” Extreme Weather Rain Cap

100112163 3” Concentric PVC Termination

FIRESTOP

100112408 4” Firestop

100112591 5” Firestop

ROOF FLASHING

100112412 4” Flat Roof Flashing

100112592 5” Flat Roof Flashing

100112545 3”

100112546 4”

100112547 5”

Direct Vent, Concentric Sidewall
Termination Kit

Includes : DV Conversion Kit, Concentric Termination,
Universal Adaptor 3-in-1, Aluminum Flex and Gear Clamp

100112421

100112420

100112602

100112603

100112606

100112601

5.0” to 10.0”
3” Intake, 4”
Exhaust

12.0” to 18.0”
3” Intake, 4”
Exhaust

5.0” to 10.0”
4” Intake, 4”
Exhaust

12.0” to 18.0”
4” Intake, 4”
Exhaust

5.0” to 10.0”
5” Intake, 5”
Exhaust

12.0” to 18.0”
5” Intake, 5”
Exhaust

100112411 4” Angled Roof Flashing

100112593 5” Angled Roof Flashing

STORM

COLLAR

100112410 4” Storm Collar

100112590 5” Storm Collar

VENT CONVERSION KIT

DIRECT

100112184

100112186

Direct Vent Conversion Kit for
Indoor models KJr2/K4/D2

Direct Vent Conversion Kit for
Model M50

Note: KJr2/110U, H3M, K4/310U, D2/510U, H3J, H3S, H3 series are compatible with 4” components. M50 series is compatible with 5” components.

59

ACCESSORIES

T-KJr2/TK-110U-I

TK-110C-NI

T-KJr2-OS/TK-110U-E

TK-310C-NI

T-K4-IN/TK-310U-I

T-K4-OS/TK-310U-E

T-D2-IN/TK-510U-I

TK-510C-NI

T-D2-OS/TK-510U-E

T-H3M-DV

T-H3J-DV

T-H3M-OS

T-H3S-DV

T-H3J-OS

T-H3S-OS

T-H3-OS/TK-540P-NEH

T-H3-DV/TK-540P-NIH

T-M50-NG

ACCESSORIES

100112194 Outdoor Vent Cap x

100266729,
100266730

100112188

Recess Box
Standard
Flange

x x x x

x x

100112187 x* x* x x x x
100112190 x

Pipe Cover

100112718 x x x x x x x
100187904 x x

100112691

100112183

Multiple Unit
Controller

x x* x* x x x x

x x x x

100112155 x x x

100209924 x x* x* x x* x* x x* x* x x x x x x

Remote Temperature
Controller

100276687

x** x**

x*** x***

TCT-199I/O

100112572 x

100112156

x x x x x x x x x x x x x x x x x x

Isolation Valves (Lead Free)

100112255 x

100112159 Neutralizer x x x x x x x x x

100113129

100113130

100291509

100291510

PVC Adapter for
Common Venting

Non-Return Valve for
Common Venting

®

Product Preservers

Anti-Scale

System

Product Preservers
Replacement Cartridge

x x x x

x x x x

x x x x x x x x x x x x x x x x x x x

x x x x x x x x x x x x x x x x x x x

*Compatible with Ultra-Low NOx models only
**Compatible with H3 models only
***Compatible with 540P models only

60

Hard Water and Tankless Heaters

Hard water can adversely affect plumbing systems, from water piping to water fixtures and even down to the water heating
system. For piping and fixtures, hard water can create more pressure loss and reduce water flow. For water heaters, it can
even reduce energy efficiency and damage the heater. This is especially true for tankless water heaters and it is important to
understand what hard water is, what hard water does, and how to protect your tankless water heater from possible damage
caused by hard water.

What is hard water and hard water scale?

Very simply, hard water is defined as water that has a high mineral content, specifically in magnesium and calcium (Ca2+ and
Mg2+ ions). Hard water is not considered a health risk and these minerals generally remain dissolved in the water. However,
the problems arise when the minerals precipitate out of the water and leave behind a solid mineral buildup. This buildup is
called hard water scale, and it is this scale that reduces water flow through pipes and fixtures, reduces the energy efficiency
of water heating equipment and, at worst, causes irreversible damage to the heat exchangers within tankless water heaters. It
is important to note that the likelihood of scale formation is only based on the hardness levels of the water and the temperature
of the water, not on the material the scale is adhering to. For example, hard water scale would form equally on a copper
surface as it would on a stainless steel surface, given the same hardness level and temperature of water.

Copper Fin

What does hard water scale do to
my water heater?

When hard water scale forms a layer coating on the inside wall of
a tankless heat exchanger fin pipe, it acts as a thermal insulator. This
insulation effectively prevents a significant amount of heat from the
burners to properly transfer into the water within the piping. Because
the heat is not transferring into the water, the heat exchanger material is
forced to retain this excess heat, eventually overheating and becoming
damaged. Once the material has degraded enough, the heat exchanger
piping eventually gives way and water leakage occurs.

With Treatment

Without Treatment

Full water flow and heat transfer

Full heat transfer

Limited water flow
Limited heat transfer

Copper Tube

Copper Fin

Copper Tube

Picture shows a clean
HX with treatment.

Scale buildup from
untreated water.

How is the hardness of
water measured?

Water hardness is measured in either parts per
million (ppm) or grains per gallon (gpg). Anything
that measures above 3 gpg is generally considered
hard (United States Geological Survey) and it is
advised at this point to look into water treatment. The
U.S. Department of Interior and the Water Quality
Association have classified water hardness under
several levels:

Burner

CLASSIFICATION

MG/L OR PPM

(PARTS PER

MILLION)

GPG (GRAINS

PER GALLON)

Soft 0 - 17 0 - 1
Slightly Hard 17 - 60 1 - 3.5
Moderately Hard 61 - 120 3.5 - 7.0
Hard 121 - 180 7.0 - 10.5
Very Hard 180 and above 10.5 and above

61

Where is hard water found?

OVER 14 gpg

10 to 14 gpg

7 to 10 gpg

3 to 7 gpg

LESS than 3 gpg

Extremely Hard

Very Hard

Hard

Moderately hard

Slightly Hard

Hard water is everywhere. In fact, more than 85% of American homes have hard water.

ALASKA

OVER 14 gpg

10 to 14 gpg

7 to 10 gpg

3 to 7 gpg

LESS than 3 gpg

Extremely Hard

Very Hard

Hard

Moderately hard

Slightly Hard

HAWAII

PUERTO RICO

How do I prevent hard water scale?

Fortunately, there are quite a few great options to choose from when looking to protect water heating equipment from scale
buildup. These solutions range in cost, maintenance and application, so it is always best to consult with water treatment
professionals before making the final decision on a water treatment solution.

®

Product Preservers

particles.
These crystals stay suspended in the water and are passed to drain.

: Prevents scale by transforming dissolved hardness minerals into harmless, inactive microscopic crystal

• This system does not add chemicals to the water or require electricity. It is virtually maintenance free only requiring a simple

filter change every two years.

Ion exchanger water softeners: Water softeners are probably the most common solution used today for eliminating hard water.

Calcium and magnesium ions are removed from the water and replaced with sodium ions. Without the calcium and
magnesium, hard water scale cannot form.

Siliphos: Interferes with the ability of (calcium and magnesium) scale to crystallize. The suspended scale stays in the water and

goes down the drain.

Flow Rate Based Ground Water Temperature (assume 120°F Set point)

Product Preservers®
protects your tankless
heat exchanger from
scale formation.

Refer to the chart to the
right to properly size
for your application.

Ground Water Temperature (°F)

Tankless

Model

85°F 6.6 8 9.3 6.4 6.6 8.0 10.0 14.5 10.0
80°F 5.7 7.8 8.2 5.6 6.6 8.0 9.5 14.5 9.5
75°F 5.1 6.9 7.3 5.0 6.6 7.6 8.4 13.5 8.4
70°F 4.6 6.2 6.5 4.5 6.1 6.8 7.6 12.2 7.6
65°F 4.2 5.7 5.9 4.1 5.5 6.2 6.9 11.0 6.9

Warmer Climate

60°F 3.8 5.2 5.4 3.7 5.1 5.7 6.3 10.1 6.3
55°F 3.5 4.8 5.0 3.4 4.7 5.3 5.8 9.4 5.8

50°F 3.3 4.5 4.7 3.2 4.3 4.9 5.4 8.7 5.4

45°F 3.1 4.2 4.4 3.0 4.1 4.6 5.0 8.1 5.0

Colder

40°F 2.9 3.9 4.1 2.8 3.8 4.3 4.7 7.6 4.7

Climate

35°F 2.7 3.7 3.8 2.6 3.6 4.0 4.5 7.2 4.5

KJr2/

110U/

110C

K4/

310U/

310C

D2/

510U/

510C

H3M H3J H3S

H3/

540P

M50 CT-199

100291509 Product Preservers® Anti-Scale System

Requires multiple units

62

Models

H3M Series

T-H3M-DV

T-H3M-OS

High efficiency

ultra-low NOx

condensing

tankless.

3” PVC venting.

0” clearance to

combustible.

Connection:

Gas/Water

Power

1/2” Gas

3/4”

Water

120 VAC

Venting Intake

Exhaust

Intake & Exhaust 3”,

70’ Max, 5 elbow

Max

OR

4”, 100’ Max,

5 elbow Max

Easy-Link

(EL)

Multi-Unit

(MU)

N/A

Temperature

(with

remote)

120 - 140

(100 - 140)

GPM

(Max)

Per Unit

6.6

I = Indoor

Uniform

Energy

Factor

I: 0.90

O: 0.91

Max

BTU/h

120,000

O = Outdoor

Dimension/

Weight

H = 22-7/8”

W = 13-7/8”

D = 10-3/4”

44 lbs

H3J Series

H3S Series

Condensing

H3 Series

540P Series

T-H3J-DV

T-H3S-DV

T-H3-DV

TK-540P-NIH

T-H3J-OS

T-H3S-OS

T-H3-OS

TK-540P-NEH

High efficiency

ultra-low NOx

condensing

tankless.

3” PVC venting.

0” clearance to

combustible.

High efficiency

ultra-low NOx

condensing

tankless.

3” PVC venting.

0” clearance to

combustible.

High efficiency

ultra-low NOx

condensing

tankless.

3” PVC venting.

0” clearance to

combustible.

High efficiency

ultra-low NOx

condensing

tankless with

integrated

recirculation

pump.

3/4”
Gas/
Water

120 VAC

3/4”
Gas/
Water

120 VAC

3/4”
Gas/
Water

120 VAC

3/4”
Gas/
Water

120 VAC

Intake & Exhaust 3”,

70’ Max, 5 elbow

Max

OR

4”, 100’ Max,

5 elbow Max

Intake & Exhaust 3”,

70’ Max, 5 elbow

Max

OR

4”, 100’ Max,

5 elbow Max

Intake & Exhaust 3”,

70’ Max,

5 elbow Max

OR

4”, 100’ Max,

5 elbow Max

Intake & Exhaust 3”,

70’ Max,

5 elbow Max

OR

4”, 100’ Max,

5 elbow Max

N/A

N/A

(EL) 4 units

(MU) 20

units

(EL) 4 units

120 - 140

(100 - 140)

120 - 140

(100 - 140)

120 - 160

(100 - 160)

120 - 140

(100 - 140)

6.6

I: 0.94

O: 0.95

8.0 I: 0.95
O: 0.94

10.0

10.0

I: 0.93

O: 0.95

I: 0.93

O: 0.95

160,000

180,000

199,000

199,000

H = 23-5/8”

W = 17-3/4”

D = 11-3/4”

58 lbs

H = 23-5/8”

W = 17-3/4”

D = 11-3/4”

58 lbs

H = 23-5/8”

W = 17-3/4”

D = 11-3/4”

59 lbs

H = 23-5/8”

W = 17-3/4”

D = 11-3/4”

59 lbs

KJr2 Series

T-KJr2-IN

T-KJr2-OS

Great for apart-

ments, condos

K4 Series

T-K4-IN

T-K4-OS

shower over the

110 at minimal

increase in cost.

D2 Series

T-D2-IN

T-D2-OS

Non-Condensing Low NOx

and summer

cabins.

Adds 1 more

Well suited

for light

commercial

applications.

Commerical-

grade copper

3/4”
Gas/
Water

120 VAC

3/4”
Gas/
Water

120 VAC

3/4”
Gas/
Water

120 VAC

I Model:

3” Intake, 50’ Max

4” Exhaust, 50’ Max

I Model:

3” Intake, 50’ Max

4” Exhaust, 50’ Max

I Model:

3” Intake, 50’ Max

4” Exhaust, 50’ Max

N/A

N/A

(EL) 4 units

113°F,
122°F,
131°F,
140°F

(99 - 167)

113°F,
122°F,
131°F,
140°F

(99 - 167)

104°,
113°F,
122°F,
140°F

(100 - 176)

6.6

8.0

10.0

I: 0.79

O: 0.79

I: 0.80

O: 0.80

I: 0.80

O: 0.80

140,000

190,000

199,000

H= 20-1/4”

W= 13-3/4”

D= 7-3/4”

33 lbs

H= 20-1/4”

W= 13-3/4”

D= 9-1/2”

38 lbs

H= 20-1/4”

W= 13-3/4”

D= 9-1/2”

39 lbs

63

Models

110C Series

TK-110C-NI TK-310C-NI TK-510C-NI

310C Series

Great for

apartments,

condos and

summer cabins.

Connection:

Gas/Water

Power

3/4”

Gas/Water

120 VAC

Venting Intake

Exhaust

3” / 5” Concentric,

43’ Max

Easy-Link

(EL)

Multi-Unit

(MU)

N/A

Temperature

(with

remote)

120 - 140

(100 - 140)

I = Indoor

GPM

(Max)

Per Unit

Uniform

Energy

Factor

BTU/h

6.6 0.81 140,000

O = Outdoor

Max

Dimension/

Weight

H= 20-1/4”

W= 13-3/4”

D= 7-3/4”

33 lbs

Adds 1 more

shower over the

110 at minimal

increase in cost.

510C Series

Well suited for

light commercial

applications.

Commerical-grade

copper

110U Series

TK-110U-I

TK-110U-E

Great for

apartments,

condos and

summer cabins.

Non-Condensing Ultra-Low NOx

310U Series

TK-310U-I

TK-310U-E

Adds 1 more

shower over the

110 at minimal

increase in cost.

510U Series

TK-510U-I

TK-510U-E

Well suited for

light commercial

applications.

Commericalgrade

copper

3/4”

Gas/Water

120 VAC

3/4”

Gas/Water

120 VAC

3/4”

Gas/Water

120 VAC

3/4”

Gas/Water

120 VAC

3/4”

Gas/Water

120 VAC

3” / 5” Concentric,

43’ Max

3” / 5” Concentric,

43’ Max

I Model:

3” Intake, 60’ Max

4” Exhaust, 60’ Max

I Model:

3” Intake, 60’ Max

4” Exhaust, 60’ Max

I Model:

3” Intake, 60’ Max

4” Exhaust, 60’ Max

N/A

(EL) 4 units

(MU) 20 unit

N/A

N/A

(EL) 4 units

(MU) 20

units

120 - 140

(100 - 140)

104 - 185

(100 - 176)

120 - 140

(100 - 140)

120 to 140

(100-140)

120 - 140

(100 - 160)

8.0 0.82 190,000

10.0 0.81 199,000

I: 0.81

6.6

8.0

10.0

O: 0.81

I: 0.82

O: 0.82

I: 0.82

O: 0.81

140,000

190,000

199,000

H= 20-1/4”

W= 13-3/4”

D= 9-1/2”

38 lbs

H= 20-1/4”

W= 13-3/4”

D= 9-1/2”

39 lbs

H= 20-1/4”

W= 13-3/4”

D= 7-3/4”

33 lbs

H= 20-1/4”

W= 13-3/4”

D= 9-1/2”

38 lbs

H= 20-1/4”

W= 13-3/4”

D= 9-1/2”

39 lbs

M50 Series

ASME
model
available

CT-199 Series

TCT-199I

Commercial

T-M50

TCT-199O

Generates Most
GPM in tankless

industry.

14.5 GPM (Max).
Commercial-grade

copper

alloy. LED display

High efficiency

ultra-low NOx

condensing

tankless.

3” PVC venting.

0” clearance to

combustible.

1”

Gas/Water

120 VAC

3/4”

Gas/Water

120 VAC

5” Intake, 50’ Max

5” Exhaust, 50’ Max

Intake & Exhaust 3”, 70’

Max,

5 elbow Max

OR

4”, 100’ Max,

5 elbow Max

(EL) 4 units

(MU) 10

units

(EL) 4 units

(MU) 20

units

100 - 185

(100 - 185)

100 - 185

(100 - 185)

14.5 (Up
to 145

GPM max

with 10 unit

system)

10.0 (Up
to 200

GPM max

with 20 unit

system)

Thermal

Efficiency

NG: 80.2%

LP: 82.4%

Thermal

Efficiency:

96%

I: 0.93

O: 0.95

380,000

199,000

H= 25-1/4”

W= 24-3/4”

D= 11-3/4”

112 lbs

H = 23-5/8”

W = 17-3/4”

D = 11-3/4”

59 lbs

64

500 Tennessee Waltz Pkwy

Ashland City, TN 37015

Toll Free: 877.737.2840

Takagi | © January 2019 | takagi.com | TBGBR00210