Takagi T-M50 User manual

Mobius Water Heater™
Model T-M50 / T-M50 ASME
Suitable for potable water heating and space heating
T-M50 / T-M50 ASME
On-Demand Water Heater
Installation Manual and Owner’s Guide
FEATURING
•ENDLESS HOT WATER
•ON-DEMAND USAGE
•COMPACT, SPACE SAVING
•ENERGY CONSERVATION
•COMPUTERIZED SAFETY
•NO PILOT LIGHT
•EASY LINK SYSTEM
WARNING
This product must be installed and
serviced by a licensed plumber, a
licensed gas fitter, or a professional
service technician. Improper installation
and/or operation, or installation by an
unqualified person, will void the
warranty.
WARNING
If the information in this manual is not
followed exactly, a fire or explosion may
result, causing property damage,
personal injury, or death.
TAKAGI Industrial Co. USA, Inc.
5 Whatney
Irvine, CA 92618
Toll Free: [phone] USA
Toll Free: [phone] CANADA
For supplying potable
hot water
ASME model ONLY

- 2 -
CONTENTS
*40 psi or above is recommended for maximum flow
NOTE
*All references to the T-M50 also refer to the
T-M50 ASME model
*Check the rating plate to ensure this product
matches your specifications.
*In accordance with ANSI Z21.10.3 and
SCAQMD Rule 1146.2, CO emission does not
exceed 400 PPM for normal input
SPECIFICATIONS
Natural Gas Input
(Operating Range) Min: 15,000 Btu/h Max: 380,000 Btu/h
LPG Input
(Operating Range) Min: 15,000 Btu/h Max: 380,000 Btu/h
Gas Connection 1” NPT
Water Connections 1” NPT
Water Pressure 15 - 150 psi *
Natural Gas Pressure
Inlet Min. 5” WC
Max. 10.5” WC
LP Gas
Pressure Inlet Min. 8” WC Max. 14” WC
Manifold Pressure Natural: 2.8” WC
Propane: 3.8” WC
Weight 112lbs.
Dimensions H25.3”×W24.8”×D11.8”
Ignition Electric Ignition
Supply 120VAC (60Hz)
Operation 178 W
(1.48A)
Standby 16 W
(0.13A)
Electric Consumption
Freeze-
Protection 271 W
(2.26A)
SPECIFICATIONS……………………….
INTRODUCTION…………………………
SAFETY GUIDELINES………………....
INSTALLATION…………………………..
General…………………………………
Included Accessories…….……………
Outdoor Installation……………………
Indoor Installation…………………......
Direct Intake Vent System…………….
Venting Instructions………………......
Gas Supply / Gas Pipe Sizing………..
Water Connections……………………
Pressure Relief Valve…………………
Electrical Connections……………......
Remote Controller Connection………
Pump Connection… … … … … … …
Easy Link System … … … … … … …
Multi-Unit System………………………
Initial Operation………………………..
NORMAL OPERATION………………….
Normal Operation…………………......
Flow……………………………………..
Freeze Protection System…………...
Temperature Settings………………….
Maintenance and Service…………….
GENERAL TROUBLESHOOTING… … .
WIRING DIAGRAM …………………… ..
OPERATING SAFETY…………………..
APPLICATIONS………………………......
Re-Circulation……………...................
Dual-Purpose Heating………………...
ADDITIONAL CLEARNCES……………..
OPTIONAL ITEMS………...……………..
COMPONENTS DIAGRAM…………….
PARTS LIST………………………………
OUTPUT TEMPERATURE CHART……
PRODUCT REGISTRATION AND
LIMITED WARRANTY……………….......
2
3
5
6
7
7
8
10
11
12
16
18
19
20
21
22
24
27
29
30
30
32
32
33
34
35
38
39
41
41
42
43
44
45
49
51
51
Takagi reserves the right to discontinue, or change at any time, specifications
or designs without notice and without incurring obligations.

- 3 -
INTRODUCTION
1. A hot water tap is turned on.
2. Water enters the heater.
3. The water flow sensor detects the water flow.
4. The computer automatically ignites the burner.
5. Water circulates through the heat exchanger and then gets hot.
6. The computer will modulate the gas supply valve and water flow to produce the right
amount of hot water at the correct temperature.
7. When the tap is turned off, the unit shuts down.
*This diagram illustrates
Takagi’s tankless water
heater design concepts
only and is not accurate to
the T-M50’s physical
description.
•This manual provides information necessary for the installation, operation, and
maintenance of the Mobius T-M50 water heater.
•The model description is listed on the rating plate which is attached to the front cover of
the water heater.
•Please read all installation instructions completely before installing this product.
•If you have any problems or questions regarding this equipment, consult with Takagi or its
local re
p
resentative.
•The T-M50 Water Heater is an on-demand, tankless water heater designed to efficiently
su
pp
l
y
endless hot water for
y
ou
r
needs.
•T-M50 has two heat exchangers. The primary and secondary heat exchangers alternate
roles, extendin
g
the life of the T-M50
(
see
p
. 4
)
.
•The principle behind the T-M50 Water Heater is simple:

- 4 -
TWO COMBUSTION SECTIONS WITHIN THE T-M50
The T-M50 contains two combustion sections. The section that turns on first is whichever
section the T-M50 decides is the primary section. The moment at which the secondary section
fires will depend on the total flow rate and set temperature of the water heater:
Flow rate at which the secondary section fires
( GPM ) T-M50 set temperature (°F)
3.2 100-120
2.9 125,130
2.6 140
2.4 145,150
2.1 155-185
Example: If the set temperature is 120ºF:
＊The section(s) in operation is indicated by the black square(s).
Right combustion section
＊The primary and secondary section will reverse roles every 100 firing cycles or every 12 hours of unit operation.
Left combustion section
or
T-M50 T-M50 T-M50 T-M50
Depending on which side is the primary section
Total Flow < 0.5 GPM
(no section turns on) 0.5 GPM ≦Total Flow < 3.2
GPM
(p
rimar
y
section fires onl
y)
3.2 GPM < Total Flow
(both primary and
secondary sections fire)

- 5 -
SAFETY GUIDELINES
•Installation and service must be performed by a qualified installer (for
example, a licensed plumber or gas fitter), otherwise the warranty by Takagi
will be void.
•The installer (licensed professional) is responsible for the correct
installation of your Mobius T-M50 Water Heater and for compliance with all
national, state/provincial, and local codes.
PLEASE READ THIS MANUAL CAREFULLY AND FOLLOW ALL DIRECTIONS.
GENERAL
1. Follow all local codes, or in the absence of local codes, follow the most recent edition of
the National Fuel Gas Code: ANSI Z223.1/NFPA 54 in the USA or CAN/CSA B149.1
Natural Gas, Propane Installation Code in Canada.
2. Properly ground the unit in accordance with all local codes or in the absence of local codes,
with the National Electrical Codes: ANSI/NFPA 70 in the USA or CSA standard C22.1
Canada Electrical Code Part 1 in Canada.
3. Carefully plan where you intend to install your T-M50 Water Heater. Please ensure:
•Your water heater will have enough combustible air and
proper ventilation.
•Locate your heater where water leakage will not damage
surrounding areas (please refer to p. 6).
4. Check the rating plate for the correct GAS TYPE, GAS
PRESSURE, WATER PRESSURE and ELECTRIC RATING.
*If this unit does not match your requirements, do not install and
consult with Takagi.
5. If any problem should occur, turn off all hot water taps and turn off
the gas. Then call a trained technician or the Gas Company or the
manufacturer.
WARNING
•Water temperatures over 125ºF can cause severe burns instantly or death from
scalding. The water temperature is set at 120ºF (49ºC) from the factory to minimize any
scalding risk. Before bathing or showering always check the water temperature.
•Do not store or use gasoline or other flammables, vapors, or liquids in the
vicinity of this appliance.
•Do not reverse the water and/or gas connections as this will damage
the gas valves and can cause severe injury or death. Follow the
diagram on p. 18 when installing your water heater:
•Do not use this appliance if any part has been in contact with or been
immersed in water. Immediately call a licensed plumber, a licensed gas
fitter, or a professional service technician to inspect and/or service the
unit if necessary.
•Do not disconnect the electrical supply if the ambient temperature will drop below
freezing. The Freeze Prevention System only works if the unit has electrical power. The
warranty will not be covered if the heat exchanger is damaged due to freezing. Refer to
the section on the Freeze Prevention System on p. 32 for more information.
WARNING
Prohibited
Rating plate

- 6 -
INSTALLATION
All gas water heaters require careful and correct installation to ensure safe and efficient
operation. This manual must be followed exactly. Read the “Safety Guidelines” section at the
beginning of this manual.
•The warranty will not cover damage caused by water quality. Water
hardness that leads to scale formation and/or corrosion may
affect/damage the water heater. Hard water scaling and/or corrosion must
be avoided or controlled by proper water treatment.
•TAKAGI recommends using the Takagi direct vent kit, when the water
heater is installed in a beauty salon. Some chemicals used in a beauty
salon may affect the flame sensor. Water heater may not work properly.
•Although the T-M50 is designed to operate with minimal sound, TAKAGI
does not recommend installing the unit on a wall adjacent to a
bedroom, or a room that is intended for quiet study or meditation, etc.
•Locate your heater close to a drain where water leakage will not do damage
to surrounding areas. As with any water heating appliance, the potential for
leakage at some time in the life of the product does exist. Takagi will not be
responsible for any water damage that may occur. If you install a drain pan
under the unit, ensure that it will not restrict the combustion air flow.
•The T-M50 weighs 112 lbs. Ensure that any and all support structures
(whether it is installed on a wall, on a support stand, etc.) have enough
strength to support and hold the T-M50.
•When handling the T-M50, do not place your hands inside the flue
collar. Injury may result.
•TAKAGI does not recommend installing unit in an attic due to safety
issues. If you install your T-M50 in an attic:
•Make sure your unit will have enough combustion air and proper
ventilation.
•Keep the area around your T-M50 clean. When dust collects on the
flame sensor, the water heater will shut down on errors.
•If the above conditions cannot be met, use the direct vent conversion kit
TM-DV50.
•Locate unit for easy access for service and maintenance.
•A drain pan is required to be installed under the water heater in case of
leaks.
WARNING
CAUTION

- 7 -
GENERAL
1. The manifold gas pressure is preset at the factory. It is computer controlled and should
not need adjustment.
2. Maintain proper space for servicing. Install the unit so that it can be connected or
removed easily. Refer to p. 8 and p. 10 for proper clearances.
3. The electrical connection requires a means of disconnection, to terminate power to the
water heater for servicing and safety purposes.
4. If you will be installing the unit in a contaminated area with a high level of dust, sand,
flour, aerosols or other contaminants/chemicals, they can become airborne and enter
and build up within the fan and burner causing damage to the unit. In those
environments (e.g. residential or commercial laundry facilities, hair salons, pet salons,
chemical plants etc.), please purchase the optional TM-DV50 direct vent conversion kit
and convert the T-M50 to a sealed combustion unit. Direct venting allows the T-M50 to
draw fresh intake air from the outside. The warranty will not cover damage caused to
the unit due to installation in a contaminated environment that has not been converted
using the TM-DV50.
5. Particles from flour, aerosols, and other contaminants may clog the air vent or reduce
the functions of the rotating fan and cause improper burning of the gas. Regularly ensure
that the area around the unit is dust- or debris-free; regular maintenance is
recommended for these types of environment.
6. Do not install the unit where the exhaust vent is pointing into any opening in a building or
where the noise may disturb your neighbors. Make sure the vent termination meets the
required distance by local code from any doorway or opening to prevent exhaust from
entering a building (refer to p. 15).
INCLUDED ACCESSORIES
Check that the installation manual, the communication cable, and the warranty card are
included with the unit.
Items
Manual
Communication Cable
Warranty Card
Qt
y
: 1
Qty: 1
Qty: 1

- 8 -
The dark square is the direction
the dipswitch should be set to.
Keep the clearances.
OUTDOOR INSTALLATION
1. Follow all local codes, or in the absence of local codes, follow the most recent edition of
the National Fuel Gas Code: ANSI Z223.1/NFPA 54 in the USA or CAN/CSA B149.1
Natural Gas, Propane Installation Code in Canada.
2. Install outdoors only in areas with mild, temperate climates.
3. Ensure that the unit is set for outdoor installation. Locate the center computer board.
On the center computer board, locate the lower bank of dipswitches to the right of the
7-Seg. LED on the computer board. The ‘OUT’ dipswitch on that bank should be
switched to its ‘ON’ (up) position (Do not adjust the upper bank of dipswitches).
4. The outdoor vent cap must be used when unit is installed outdoor. Takagi requires the
use of its part No. TM-VC50.
5. When installed outdoors, the T-M50 water heater shall be wall-mounted or mounted on a
stand. Locate the water heater in an open, unroofed area and maintain the following
minimum clearances:
Make sure power to the unit is
turned OFF before changing
the dipswitch settings.
TMP1 TMP2 TMP3 MODE DIRE OUT P-ALARM MST
O
N
1 2 3 4 5 6 7 8
Lower Bank of Dipswitches
There is a 2” clearance from the
left and right sides of the unit to
combustible and non-combustible
surfaces. However, if any portion
or area of the surface is exposed to
the exhaust fumes (i.e. directly to
the sides of the vent cap), that
surface must be at least 24”
away.
7-Seg LED
Lower bank of
dipswitches
Upper bank of
dipswitches
Back 0.5”
Side 2”
Side 2”
Top 36”
Bottom 12”
*Side 24”
*Side 24”
Front 4”
(24” Recommended
for Maintenance)
*Front 24”

- 9 -
WARNING FOR INSTALLATION LOCATIONS
Do not install the heater where water, debris
or flammable vapors may get into the flue
terminal. This may cause damage to the
heater and void the warranty.
Do not have the vent terminal pointing toward
any opening into a building. Do not locate
your heater in a pit or location where gas and
water can accumulate.
Do not install this water heater under an
overhang less than 3 feet from its top or
eaves. The area under an overhang must be
open to three sides.
Do not install the water heater vent terminator
within 1 ft. in the USA of any air intake or
building opening, and with in 3 ft. in Canada
of any air intake or building opening. (Refer to
p.15)
Do not install next to a dryer or any source of
airborne debris that can be trapped inside the
combustion chamber, unless the system is
direct vented.
Prohibited Prohibited
3 Ft.
Takagi
1 Ft.（USA ）
3 Ft.（Canada ）
1 Ft.（USA ）
3 Ft.（Canada ）
1 Ft.（USA ）
3 Ft.（Canada ）

- 10 -
Keep the clearances.
WARNINGINDOOR INSTALLATION
1. Follow all local codes, or in the absence of
local codes, follow the most recent edition
of the National Fuel Gas Code: ANSI
Z223.1/NFPA 54 in the USA or CAN/CSA
B149.1 Natural Gas, Propane Installation
Code in Canada.
2. When installed indoors, the T-M50 water
heater shall be located in an area to
maintain the following minimum clearances
around the unit:
Combustion Air Supply
The water heater location must provide enough air for proper combustion and ventilation of the
surrounding area. See the latest edition of ANSI Standard Z223.1 or any applicable local codes.
In general, these requirements specify that if the unit is installed in a confined space, there must
be a permanent air supply opening.
Minimum recommended air supply opening size for water heater:
Water heater size
When drawing make-up air from
outside the building
When drawing make-up air from inside
the building (from other rooms within)
25.3 Sq. IN 380 Sq. IN
MAX
380,000 BTU
/h
When combustion air is supplied
from outside the building, an
opening communicating directly
with the outside should have a
minimum free area of one
square inch per 15,000 BTUH
input of the total input rating of
water heater in the enclosed
area.
When combustion air is supplied from
inside the building, an opening
communicating with the rest of the
dwelling should have a minimum free
area of one square inch per 1,000
BTUH input of the total input rating of
water heater in the enclosed area.
This opening should never be less
than 199 sq. in.
Combustible Air Supplied by Mechanical fan or Make up air device
The T-M50 water heater is equipped with a combustible air sensor that will shut off the unit
when inadequate combustible air supply to unit is detected.
•If a mechanical fan or make up air device is used to supply air to the water heater or
utility room, the installer should make sure it does not create drafts which could cause
nuisance shutdowns.
•If a blower is necessary to provide adequate combustion air to the water heater, the
blower and water heater must be set up so that the water heater cannot fire unless the
blower is operating. Possible methods include the use of the T-M50’s internal fan
control port or the use of external flow sensors/transmitters and relays.
Top 12”
Side 2”
Side 2”
Front 4”
(24” Recommended
for Maintenance) Bottom 12”
Back 0.5”

- 11 -
The dark square is the direction
the dipswitch should be set to.
INTAKE EXHAUST
LOUVER COVER PLATES
DIRECT INTAKE VENT SYSTEM
This T-M50 water heater may be converted to a direct vent (sealed combustion) appliance by
installing an adapter (Part No. TM-DV50) which will bring all required combustible air from
outside the building. When installing the TM-DV50 conversion kit, please follow all instructions
included with the kit.
•The T-M50 must be installed in a location where the proper amount of combustible air
will be available to it at all times without obstructions.
•If used as a direct vent appliance, the T-M50 requires a 5” combustible air supply pipe.
The intake pipe must be sealed airtight.
•Air supply pipe can be made of ABS, PVC, galvanized steel, corrugated aluminum,
corrugated stainless steel or Category III stainless steel.
•Change the dipswitch settings to the direct vent system. (See diagram below)
•Sidewall venting is recommended for the direct vent system.
•Takagi recommends running the exhaust vent and the intake pipe parallel.
TM-DV50 Direct Vent
Conversion Kit
Make sure power to the unit is
turned OFF before changing
the dipswitch settings.
O
N
TMP1 TMP2 TMP3 MODE DIRE OUT P-ALARM MST
1 2 3 4 5 6 7 8
Lower Bank of Dipswitches
7-Seg LED
Lower bank of
dipswitches
Upper bank of
dipswitches
TM-DV50 DIRECT VENT
CONVERSION KIT

- 12 -
VENTING INSTRUCTIONS
WARNING: Improper venting of this appliance can result in excessive levels of
carbon monoxide which can result in severe personal injury or death.
This water heater must be vented in accordance with the section “Venting of Equipment" of the
latest edition of the Natural Fuel Gas Code: ANSI Z223.1, All applicable local building codes,
Section 7 of CAN/CSA B149.1 Natural Gas in Canada, Propane Installation Code in Canada.
EXHAUST VENT
This is a Category III appliance and must be vented accordingly. The vent system must be
sealed air tight. All seams and joints without gaskets must be sealed with high heat resistant
silicone sealant or UL listed aluminum adhesive tape having a minimum temperature rating of
350ºF. For best results, a vent system should be as short and straight as possible.
1. This Takagi water heater is a Category III appliance and must be vented accordingly with
any 5” vent approved for use with Category III or Special BH type gas vent.
2. The following are UL listed manufacturers: ProTech Systems Inc. (FasNSeal), Flex-L Inc.,
Z-Flex Inc. (Z-Vent III), Metal-Fab Inc., and Heat-Fab Inc. (Saf-T Vent).
3. Follow the vent pipe manufacturer’s instructions when installing the vent pipe.
4. Do not common vent this appliance with any other vented appliance (Do not
terminate vent into a chimney. If the vent must go through the chimney, the vent must run
all the way through the chimney with Category III approved or Special BH vent pipe).
5. The maximum length of exhaust vent piping must not exceed 50 ft. deducting 5 ft. for each
elbow used in the venting system. Do not use more than 5 elbows.
Diameter Max. No. of Elbow Max. Vertical or Horizontal run in Length
5” 5 Ea. 50 ft
*For each elbow added, deduct 5 ft. from max. Vent length.
No. of Elbows Max. Vertical or Horizontal Length
0 50 ft.
1 45 ft.
2 40 ft.
5 25 ft.
6. When the horizontal vent run exceeds 5 ft., support the vent run at 3 ft. intervals with
overhead hangars.
7. Takagi will not be responsible for any damage to the water heater caused by condensation
from the vent. For horizontal runs, slope the vent run downwards toward the vent terminal
at a rate of ¼” per foot. For horizontal runs that do not slope downward and for vertical
runs, installing a condensate drip is recommended. Please refer to p. 14 for the diagrams.
When installing the vent system, all applicable national and local codes must be
followed. If you install thimbles, fire stops or other protective devices and they
penetrate any combustible or noncombustible construction, be sure to follow all
applicable national and local codes.

- 13 -
VENT TERMINATION
WARNING: Improper installation can cause nausea or asphyxiation, severe injury
or death from carbon monoxide and flue gases poisoning. Improper installation
will void product warranty.
•The vent terminator provides a means of installing vent pipe through the building wall and
must be located in accordance with ANSI Z223.1/NFPA 54, or in Canada with CAN/CSA-
B149.1 and local applicable codes.
•A proper sidewall vent terminator is recommended when the water heater is vented through
a sidewall. If the T-M50 is converted to a direct-vent unit, a proper sidewall direct-vent
terminator is to be used.
General rules for venting the T-M50 water heater are:
1. Place the water heater as close as possible to the vent terminator.
2. The vent collar of the water heater must be fastened directly to an unobstructed vent pipe.
3. Do not weld the vent pipe to the water heater collar.
4. Do not cut the vent collar of the unit.
5. The weight of the vent stack must not rest on the water heater.
6. The vent must be easily removable from the top of the water heater for normal service and
inspection of the unit.
7. The water heater vent must not be connected to any other gas appliance or vent stack.
8. Avoid locating the water heater vent terminator near any air intake devices. These fans
can pick up the exhaust flue products from the gas appliance and return them to the
building. This can create a health hazard.
9. Avoid using an oversized vent pipe or using extremely long runs of the pipe.
10. Locate the vent terminator so that it cannot be blocked by any debris, at any time. Most
codes require that the terminator be at least 12 inches above grade, but the installer may
determine if it should be higher depending on the job site condition and applicable codes.
11. For rooftop venting, a rain cap must be installed.

- 14 -
Horizontal Installation Diagram
Vertical Installation Diagram
•Regarding the clearance from the terminator to the air inlet or opening, refer to the next
page.
•Install a condensation drain in the venting.
•Follow the vent system to vent manufacturer’s instruction and local code.
•Do not common vent or connect any vent from other appliances to the T-M50 vent.
•Use 5” category III approved or Special BH, single or double wall stainless steel vent pipe.
Wall
Roof
Rain Cap
Roof Flashing
Sidewall
Vent
Terminator
Vertical Condensation Drain
(Install according to local codes)
TK-BF50 Vent Damper
(Recommended for freezing
weather conditions: 36°F and
below)
TK-BF50 Vent Damper
(Recommended for freezing
weather conditions: 36°F and
below)
Vertical Condensation Drain
(Install according to local codes)

- 15 -
VENT CLEARANCES
Canada U.S.A
Direct vent and
other than Direct
Vent Direct vent Other than Direct Vent
A Clearance above grade, veranda, porch,
deck, or balcony. 1 foot 1 foot 1 foot
B Clearance to window or door that may be
opened. 3 feet 1 foot 4 feet from below or
side opening. 1 foot
from above opening.
C Clearance to permanently closed window * * *
D Vertical clearance to ventilated soffit
located above the vent terminator within a
horizontal distance of 2 feet (61cm) from
the center line of the terminator. * * *
E Clearance to unventilated soffit * * *
F Clearance to outside corner * * *
G Clearance to inside corner * * *
H Clearance to each side of center line
extended above meter/regulator assembly 3 feet * *
I Clearance to service regulator vent outlet. 3 feet * *
J Clearance to non-mechanical air supply
inlet to building or the combustion air inlet
to any other application. 3 feet 1 foot 4 feet from below or
side opening. 1 foot
from above opening.
K Clearance to mechanical air supply inlet. 6 feet 3 feet 3 feet
L Clearance above paved sidewalk or
paved driveway located on public
property. 7 feet * 7 feet
M Clearance under veranda, porch deck, or
balcony. 1 foot * *
*For clearances not specified in ANSI Z223.1 / NFPA 54 or CAN/CSA-B149.1, please use clearances in
accordance with local installation codes and the requirement of the gas supplier.

- 16 -
GAS SUPPLY AND GAS PIPE SIZING
1. Turn off all electric power to the water heater if service is to be performed.
2. Turn the manual gas valve located on the outside of the unit clockwise 3to the off position.
WARNING: Conversion of this unit from natural gas to propane or vise versa
cannot be done in the field. Contact your local distributor to get the correct unit for
your gas type. Conversion done by anyone other than the manufacturer will void all
warranty. Takagi is not liable for any property and/or personal damage
resulting from unauthorized conversions.
*Check that the type of gas matches the rating plate first.
1. The minimum and maximum inlet gas pressures are:
Natural Gas Min. 5.0” WC - Max. 10.5” WC
Propane Gas Min. 8.0” WC - Max. 14.0” WC
2. Gas pressure below this specified range for the T-M50 and/or insufficient gas volume will adversely
affect performance. These pressures are measured when the T-M50 is in full operation.
3. Inlet gas pressure must not exceed the above maximum values; gas pressure above the specified
range will cause dangerous operating conditions and damage to the unit. Ensure that any and all
gas regulators used are operating properly and are providing gas pressures within the specified
range shown above.
4. Until testing of the main gas line supply pressure is completed, ensure the gas line to the T-M50 is
disconnected to avoid any damage to the water heater.
MEASURING INLET GAS PRESSURE
The T-M50 cannot perform properly without sufficient inlet gas pressure. Below are instructions on how to
check the inlet gas pressure. THIS IS ONLY TO BE DONE BY A LICENSED PROFESSIONAL.
1. Shut off the manual gas valve on the supply gas line.
2. Open a faucet. The unit should turn on and the gas in
the gas pipe line should purge. Leave the faucet on to
keep the unit running until the unit shut down due to
lack of gas supply. Then shut the faucet off.
3. Remove the screw for the pressure port located on the
gas inlet of the T-M50 shown in the diagram to the
right.
4. Connect the manometer to the pressure port.
5. Re-open the manual gas valve. Check to see that
there are no gas leaks.
6. Open some of the fixtures that use the highest flow
rate to turn on the T-M50.
7. Check the inlet gas pressure. When T-M50 is on a
maximum burn, the manometer should read from 5.0”
to 10.5” WC for Natural gas, from 8.0” to 14.0” WC for
Liquid Propane.
TO TURN OFF GAS TO APPLIANCE

- 17 -
Size the gas pipe appropriately to supply the necessary volume of gas required
for the T-M50 (380,000 BTU/H for Natural Gas or 380,000 BTU/H for Liquid
Propane) using ANSI233.1/NAPA 54 in the USA or CAN/CSA B149.1 in Canada
or local codes. Otherwise, flow capabilities and output temperatures will be
limited.
1. Install a manual gas shut-off valve between the T-M50 and the gas supply line.
2. When the gas connections are completed, it is necessary to perform a gas leak test either
by applying soapy water to all gas fittings and observing for bubbles or by using a gas leak
detection device.
3. Always purge the gas line of any debris and/or water before connecting to the gas inlet.
Natural Gas Supply Piping
Maximum Delivery Capacity of Cubic Feet of Gas per Hour of IPS Pipe Carrying Natural Gas of 0.60 Specific Gravity
Based on Pressure Drop of 0.5” WC
Based on Energy Content of 1000 BTU/Cubic Ft.: T-M50 requires 380 Cubic Ft./hr. Unit: Cubic Feet per Hour
Length of Pipe
Pipe
Size 10' 20' 30' 40' 50' 60' 70' 80' 90' 100' 125' 150' 200'
¾” 363 249 200 171 152 138 127 118 111 104 93 84 72
1” 684 470 377 323 286 259 239 222 208 197 174 158 135
1 ¼” 1404 965 775 663 588 532 490 456 428 404 358 324 278
1 ½” 2103 1445 1161 993 880 798 734 683 641 605 536 486 416
2” 4050 2784 2235 1913 1696 1536 1413 1315 1234 1165 1033 936 801
2 ½” 6455 4437 3563 3049 2703 2449 2253 2096 1966 1857 1646 1492 1277
3” 11412 7843 6299 5391 4778 4329 3983 3705 3476 3284 2910 2637 2257
Propane (LP) Gas Supply Piping
Maximum Capacity of Propane (LP) Gas Based on 11” WC supply pressure at a 1.0” WC pressure drop Unit: kBTU per Hour
Pipe Size Length in Feet
inches 10’ 20’ 30’ 40’ 50’ 60’ 70’ 80’ 90’ 100’ 125’ 150’ 200’
¾” 567 393 315 267 237 217 196 185 173 162 146 132 112
1” 1071 732 590 504 448 409 378 346 322 307 275 252 213
1 ¼” 2205 1496 1212 1039 913 834 771 724 677 630 567 511 440
1 ½” 3307 2299 1858 1559 1417 1275 1181 1086 1023 976 866 787 675
2” 6221 4331 3465 2992 2646 2394 2205 2047 1921 1811 1606 1496 1260
10’ Length
3/4” Pipe Size
Gas Sizing Example
(Natural Gas)
15’ Length
1/2” Pipe Size
10’ Length
1/2” Pipe Size
Furnace
120,000BTU
10’ Length
1” Pipe Size
T-M50
380,000BTU
10’ Length
1-1/2” Pipe Size
Range
65,000BTU
20’ Length
1-1/4” Pipe Size
Dryer
35,000BTU
15’ Length
3/4” Pipe Size
10’ Length
1-1/2” Pipe Size
Gas Meter
B
A
Based on Energy Content of 1000BTU/Cubic Ft:
Divide each appliance’s BTU requirement by 1000BTU to get
the appliances Cubic Ft. requirement.
Takagi into account the distance the appliance is from the gas
meter, look in the above gas chart to properly size the line.
For sections of the gas line supplying gas to more than one
appliance (Ex: Point A to Point B), add up the cubic ft.
requirements of the appliances that are being supplied by that
section, and size to the farthest appliance.
For Example: The section from A to B supplies gas to the
furnace, range, and dryer. Adding up the BTU requirements and
dividing by 1000 yields a cubic ft. requirement of 220 cubic ft. of
gas. The farthest appliance is the range, which is 60 ft. away
from the meter. Looking at the above chart, and under the
column of 60ft., Section A to B needs to be 1” in order to supply
220 cubic ft.

- 18 -
WATER CONNECTIONS
Do not use this water heater if any part has been submersed under water.
Immediately call a licensed professional to inspect the water heater and to replace
any damaged parts.
1. All pipes, pipe fittings, valves and other components, including soldering materials, must
be suitable for potable water systems.
2. A manual shut off valve must be installed on the cold water inlet to the water heater
between the main water supply line and the T-M50.
3. In addition, a manual shut off valve is also recommended on the hot water outlet of the unit.
If the T-M50 is installed within, or subjected to, a closed loop water system, a thermal
expansion tank must be installed.
4. Before installing the water heater, flush the water line to remove all debris, and after
installation is complete, purge the air from the line. Failure to do so may cause
damage to the heater.
5. There is a wire mesh filter within the cold inlet to trap debris from entering your heater. This
will need to be cleaned periodically to maintain optimum flow.
CAUTION: Do not reverse the hot outlet and cold inlet connections to the
T-M50 Water Heater. This will not activate the water heater.
FOR YOUR SAFETY, READ BEFORE OPERATING:
Pressure
Relief
Valve
Gas
Cold inlet
Hot out

- 19 -
PRESSURE RELIEF VALVE
The Mobius T-M50 has a high-temperature shut-off switch built in as a standard safety feature
(called a Hi-Limit switch) therefore a “pressure only” relief valve is required.
1. This unit does not come with an approved pressure relief valve.
2. An approved pressure relief valve must be installed on the hot water outlet.
3. The pressure relief valve must conform to ANSI Z21.22 or CAN 1-4.4 and installation must
follow local code.
4. The discharge capacity must be at least 380,000 BTU/h.
5. The pressure relief valve needs to be rated for a maximum of 150 psi.
6. The discharge piping for the pressure relief valve must be directed so that the hot water
cannot splash on anyone or on nearby equipment.
7. Attach the discharge tube to the pressure relief valve and run the end of the tube to within
6" from the floor. This discharge tube must allow free and complete drainage without any
restrictions.
8. If the pressure relief valve installed on the T-M50 discharges periodically, this may be due
to a defective thermal expansion tank or defective pressure relief valve.
9. The pressure relief valve must be manually operated periodically to check for correct
operation.
10. When ASME model is installed, the pressure relief valve should be conformed and
installed in accordance with ASME code.
11. For the T-M50 ASME model, the pressure relief valve must conform to and be installed in
accordance with ASME code.
Pressure
Relief
Valve
Gas
Cold inlet
Hot out
Takagi
As Close as
Possible

- 20 -
ELECTRICAL CONNECTIONS
WARNING: Follow the electrical code requirements of the local authority having
jurisdiction. In the absence of such requirements, follow the latest edition of the
National Electrical Code ANSI/NFPA 70 in the U.S. or the latest edition of CSA
C22.1 Canadian Electrical Code, Part 1, in Canada.
CAUTION: When servicing or replacing parts within the T-M50, label all wires prior to
disconnection to facilitate an easy and error free reconnection. Wiring errors can cause
improper and dangerous operation. Verify proper operation after servicing.
1. The heater must be electrically grounded. Do not attach the ground wire to either the gas
or the water piping.
2. The Mobius T-M50 water heater requires AC 120V 60 Hz electrical power supply that
is properly grounded.
•A proper disconnect (i.e. on/off switch, power plug, etc.) controlling the main power to
the T-M50 must be provided for service reasons. (Must comply with local codes).
•Connect the power supply to the T-M50 exactly as shown in the wiring diagram;
3. A green screw is provided in the junction box to ground the connection.
4. Can be hardwired or wired to a plug-in.
5. The use of a surge protector is recommended in order to protect the unit from power
surges.
Ground
Connect Power supply
AC120V 60Hz