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