Bosch TRONIC 6100 C User manual

Installation Manual
Electric Tankless Water Heaters
TRONIC 6100 C
TR6100C-18 | TR6100C-27
BTC 722103301 A |105523 |08.2022
WARNING:
This manual must only be used by a qualified
installer / service technician. Read all instructions
in this manual before installing. Perform steps in
the given order. Failure to do so could result in
substantial property damage, severe personal
injury, or death.
WARNING:
Improper installation, adjustment, alteration,
service or maintenance can cause injury, death, or
property damage.
NOTICE:
The manufacturer reserves the right to make
product changes or updates without notice and will
not be held liable for typographical errors in
literature.

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Installation Manual
Bosch Tronic 6100 C Electric Tankless Water Heaters - BTC 724001301 A (08.2022)

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Installation Manual
Bosch Tronic 6100 C Electric Tankless Water Heaters- BTC 724001301 A (08.2022)
Table of Contents
1 Key to Symbols and Safety Instructions 4
1.1 Key to Symbols 4
1.2 Safety 4
2 Prepare the Water Heater 6
2.1 lnspect Shipment 6
2.2 Water Heater Rating Label Location 6
2.3 Clearances 6
2.4 Locating the Water Heater 7
2.4.1 Installation Area (Mechanical Room) Operating Conditions 7
2.4.2 Centralized Location 8
2.4.3 Replacing an Existing Water Heater 8
3 Water Quality Requirements 8
4 Water Heater Components 9
5 Dimensions 10
6 Technical Specifications 11
7 Installation 12
7.1 Wall Mounting the Water Heater 12
7.2 Plumbing 14
7.2.1 Pressure Relief Valve 14
7.3 Installation Example 15
7.5 Scalding 16
7.6 Filling the Heater 16
7.7 Electrical Connection 17
7.8 Wiring Diagrams 18
7.8.1 Power Supply Wiring for 18 and 27kW 18
7.8.2 Internal Wiring Diagram for 18kW 19
7.8.3 Internal Wiring Diagram for 27kW 20
8 Installation Checklist 21
9 Operation 22
10 Seasonal Operation 22
11 Maintenance 23
11.1 Removing the Cover 23
11.2 Cleaning the Inlet Pre-Filter 24
11.3 Draining the Heater 24
11.4 Removing a Heating Element
25
11.5 Descaling the Heating Element 27
12 Troubleshooting 28
12.1 High Limit Switches 30
12.2 Checking Thermostat Operation 30
12.3 Testing the Heating Element 31
12.4 Testing / Changing a Triac 32

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1 Key to Symbols and Safety Instructions
1.1 Key to Symbols
Warnings
Warnings in this document are identified by a
warning triangle printed against a grey background.
Keywords at the start of a warning indicate the type and seriousness
of the ensuing risk if measures to prevent the risk are not taken.
The following keywords are defined and can be used in this document:
DANGER indicates a hazardous situation which, if not avoided, will result
in death or serious injury.
WARNING indicates a hazardous situation which, if not avoided, could
result in death or serious injury.
CAUTION indicates a hazardous situation which, if not avoided, could
result in minor to moderate injury.
NOTICE is used to address practices not related to personal injury.
Important information
This symbol indicates important information where there is no risk to
people or property.
1.2 Safety
Please read before proceeding
Installation should be made in accordance with the regulations of the
Authority Having Jurisdiction, local code authorities, and utility
companies which pertain to this type of water heating equipment.
Authority Having Jurisdiction (AHJ) – The AHJ may be a federal, state,
local government, or individual such as a fire chief, fire marshal, chief
of a fire prevention bureau, labor department or health department,
building official or electrical inspector, or others having statutory
authority. In some circumstances, the property owner or his/ her agent
assumes the role, and at government installations, the commanding
officer or departmental official may be the AHJ.
WARNING:IMPORTANT SAFETYINSTRUCTIONS
When using electrical appliances, basic safety precautions
to reduce the risk of fire, electric shock, or injury to persons
should be followed, including:
1. READ ALL INSTRUCTIONS BEFORE USING THIS WATER
HEATER.
2. This water heater must be grounded.
3. Install or locate this water heater only in accordance with
the provided installation instructions.
4. Do not use this water heater for anything other than its
intended purpose (as described in this manual). Doing so
could result in property damage and WILL VOID product
warranty.
5. This heater has more than one power supply connection
point. Never attempt to install, clean, inspect or repair,
disassemble, or service the heater without first shutting off
all power to the unit by means of the circuit breaker on the
main electrical panel.
6. Power supply wires must be rated to 194 F (90C). Refer to
technical specifications section 6 table 4 for proper wire
size.
7. The heater must be connected to a dedicated circuit
breakers. When the heater is not within sight of the
electrical circuit breakers, a circuit breaker lockout or
additional local means of disconnection for all non-
grounded conductors must be provided that is within sight
of the appliance. (Ref NEC 422.31.).
8. The plumbing installation must be completed before the
electrical installation.
9. The plumbing installation requires non-ferreous metal pipes
or reinforced stainless steel water heater connectors that
can withstand pressure up to 150 psi.
10. To ensure proper operation, the water supply flow rate must
be at least 0.5 gpm.
11. Do not install the heater where it may be subjected to direct
sunlight, rain, splashing water, or freezing temperatures.
12. Before connecting the unit to a public power network,
consult the local power supply authority to ensure the
power network meets the stated requirements.
13. Do not operate this water heater if it has damaged wiring,
if it is not working properly, or if it has been damaged or
dropped.
14. This water heater should be serviced only by qualified
service personnel. Contact the water heater installer
or a qualified service agency for examination, repair, or
adjustment.
WARNING:IMPROPEROR DANGEROUSOPERATION
Installations Must Comply With: Local, state, provincial, and
national codes, laws, regulations,ordinances and the latest
version of the National Electrical Code, NFPA No. 70.

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WARNING:IMPROPEROR DANGEROUSOPERATION
If the water heater is exposed to the following, do not
operate. Immediately call a qualified service technician.
—Fire
—Damage
—Water
—Freezing temperatures
Failure to follow this information could result in property
damage, severe personal injury, or death.
WARNING:INDOORINSTALLATION ONLY
DO NOT INSTALL OUTDOORS.This water heater is certified
for indoor installation only and is not intended for use as a
pool heater. Failure to follow these instructions could result
in FIRE, PROPERTY DAMAGE, and/or PERSONAL INJURY
OR DEATH.
WARNING:FIRE
Install all system components and piping in such a
manner that does not reduce the performance of any fire
suppression devices or system.
WARNING:IMPROPEROR DANGEROUSOPERATION
DO NOT USE THIS WATER HEATER IF ANY PART HAS BEEN
SUBMERGED IN WATER. Immediately call a qualified service
technician. The water heater MUST BE replaced if it has
been submerged. Attempting to operate a water heater
that has been submerged could create numerous harmful
conditions, such as a potential gas leakage causing a fire
and/or explosion, or the release of mold, bacteria, or other
harmful particulates into the air. Operating a previously
submerged water heater could result in property damage,
severe personal injury, or death. Water heater damage due
to flood or submersion is considered an Act of God, and
IS NOT covered under product warranty.
WARNING:IMPROPEROR DANGEROUSOPERATION
The manufacturer cannot be responsible for damages
caused by improper installation or by failure to follow the
instructions in this manual.
WARNING:HAZARDOUSVOLTAGE
When Servicing the Water Heating System be sure to
disconnect electrical power before performing service.
Failure to do so could result in electrical shock, property
damage, serious personal injury, or death.
WARNING:
This product can expose you to chemicals including Lead
and Lead components, which are known to the State
of California to cause cancer and birth defects or other
reproductive harm. For more information go to www.
P65Warnings.ca.gov.
NOTICE:PRODUCTDAMAGE, PROPERTY DAMAGE
Do not use petroleum-based cleaning or sealing compounds
in a water heating system. Gaskets and seals in the system
may be damaged. This can result in substantial property
damage.
NOTICE:PRODUCTDAMAGE, PROPERTY DAMAGE
If the water heater has been stored in a very cold location
(BELOW 32°F) before installation, handle with care until the
components come to room temperature. Failure to do so
could result in damage to the water heater.

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Water Temperature Adjustment
The water heater thermostat has been pre-set at the factory at a temperature equal
to 125°F (52°C). Follow local codes and if the water heater is going to have a set
temperature above 120°F, install an ASSE 1017 rated mixing valve to avoid severe
burns or death from scalding temperatures.
After adjusting the water temperature at the thermostat, allow the water
heater enough time to heat the water to temperature. The recommended
temperature setting is 120°F.
WARNING:SCALDHAZARD
Scald injury is heightened by increased water temperatures.
Hot water can produce 3rd degree burns in 6 seconds at
140°F and in 30 seconds at 130°F.
If the Water Heater thermostat is set too high there is
Serious Potential for SCALDING.
Children, the disabled and the elderly are at highest risk of
being scalded.
Temperature TimetoProduce SeriousBurn
120 °F (48 °C) More than 5 minutes
125 °F (51 °C) 1.5 to 2 minutes
130 °F (54 °C) Approx. 30 seconds
135 °F (57 °C) Approx. 10 seconds
140 °F (60 °C) Less than 5 seconds
145 °F (62 °C) Less than 3 seconds
150 °F (65 °C) Approx. 1.5 seconds
155 °F (68 °C) Approx. 1 second
Table 1
2 Prepare the Water Heater
2.1 lnspect Shipment
Inspect shipment for possible damage. The manufacturer's responsibility ceases
upon delivery of goods to the shipper in good condition. Any claims for damage,
shortage in shipments, or no delivery must be filed immediately against carrier by
consignee.
2.2 Water Heater Rating Label Location
When inquiring about service or troubleshooting, reference the model and serial
numbers from the water heater rating label. The serial number can also be found
inside of the unit.
Figure 1
Tronic 6100 C TR6100C-18
18 kW
0.55 GPM
7 PSI
Model Number
Serial Number
Rating Label
Location
2.3 Clearances
Heater must have room for service. Please observe the following minimum
recommended service clearances.
minimum recommended service clearance
Front 6"
Sides 6"
Top 12"
Bottom 12"
Table 2
A removable panel is acceptable to provide front clearance.
This water heater is approved for closet installation.
If you do not provide the minimum recommended service clearances
it might not be possible to service the water heater without removing it
from the space.
WARNING:FIRE,EXPLOSION
Please keep any flammable materials at least 24” (61cm)
away from the water heater and hot outlet pipe.

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NOTICE:PRODUCTDAMAGE
High heat sources (sources generating heat 100°F / 37°C
or greater, such as stove pipes, space heaters, etc.) may
damage plastic components of the water heater. Such
damages ARE NOT covered by warranty. It is recommended
to keep a minimum clearance of 8” from high heat sources.
Observe heat source manufacturer instructions, as well as
local, state, provincial, and national codes, laws, regulations
and ordinances when installing this water heater and related
components near high heat sources.
2.4 Locating the Water Heater
WARNING:INDOORINSTALLATION ONLY
DO NOT INSTALL OUTDOORS.This water heater is certified
for indoor installation only. Outdoor installations ARE NOT
covered by warranty. Failure to install the water heater
indoors could result in property damage, severe personal
injury, or death.
NOTICE:PROPERTY DAMAGE
All water heaters eventually leak. Locate the water heater
where any leakage from the relief valve, related piping, tank,
or connections will not result in damage to surrounding
areas or lower floors of the building. Any water heater
should be installed in such a manner that if it should leak
the resulting flow of water will not cause damage to the area
in which it is installed. National Plumbing codes require a
drain pan for any water heater installation. Failure to install
one is the sole responsibility of owner and/or installer.
Reference UPC 2000 (Uniform Plumbing Code) Section
510 - Protection from Damage or IPC 200 (International
Plumbing code) Section 504 - Safety Devices. Leakage
damages ARE NOT covered by warranty. In addition,
water leak detection devices and automatic water shutoff
valves are readily available at plumbing supply houses.
IT IS HIGHLY RECOMMENDED BY THE MANUFACTURER
TO INSTALL WATER LEAK DETECTION DEVICES AND
AUTOMATIC SHUTOFF VALVES IN ANY WATER HEATER
INSTALLATION WHERE A LEAKAGE OF WATER COULD
RESULT IN PROPERTY DAMAGES.
2.4.1 Installation Area (Mechanical Room) Operating Conditions
This water heater must be installed upright in the vertical position and on a
plumb surface as described in this manual.
WARNING:IMPROPEROR DANGEROUSOPERATION
DO NOT attempt to install this water heater in any other
orientation than in a upright, vertical position and on a level
surface (see Fig. 5). Doing so will result in improper water
heater operation and property damage, and could result in
serious personal injury or death.
Ensure ambient temperatures are higher than 32°F / 0°C and lower than
104°F / 40°C.
Attic ambient temperatures may frequently exceed 104°F.
WARNING:IMPROPEROR DANGEROUSOPERATION
Incorrect ambient conditions can lead to damage to the
heating system and put safe operation at risk. Ensure that
the installation location adheres to the information included
in this manual. Failure to do so could result in property
damage, serious personal injury, or death.
Avoid continuously high levels of humidity, moisture, or dust, or an area
that may be splashed with water or other liquids. DO NOT install under
water pipes or air conditioning lines that might leak or condense onto the
water heater.
When installing in a minimum clearance location, it may not be possible
to read or view some product information.
WARNING:SCALDHAZARD
Keep water heater and hot outlet piping securely out of the
reach of children to prevent tampering with the controls or
contact with an extremely hot pipe.
NOTICE:PRODUCTDAMAGE, PROPERTY DAMAGE
The service life of the water heater’s exposed metallic
surfaces are directly influenced by proximity to damp
and salty marine environments. In such areas higher
concentration levels of chlorides from sea spray coupled
with relative humidity can lead to degradation of water
heater components and cause premature water heater
failure. Such failures ARE NOT covered by warranty.

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2.4.2 Centralized Location
Choose a location for the water heater as centralized to the piping and electrical
system as possible. Also, locate the water heater and domestic water piping where
it will not be exposed to freezing temperatures. All piping should be insulated.
Additionally, place the water heater so that the drain, controls, and inlets/outlets
are easily accessible.
To save on heating costs and improve energy efficiency keep the distance
between the water heater and fixtures to a minimum to reduce heat loss
from excess piping and keep friction loss at a minimum. Ensure all water
heater piping is properly insulated to minimize heat loss.
In the State of California, the water heater must be braced, anchored,
or strapped to avoid moving during an earthquake. Contact local utilities
for code requirements in your area. Visit http://www.dsa.dgs.ca.gov or
call 1-916-445-8100 and request instructions.
WARNING:FIRE,EXPLOSION
This water heater must not be located near flammable
liquids such as gasoline, butane, liquefied propane,
adhesives, solvents, paint thinners, etc., as the controls of
this water heater could ignite these vapors and cause an
explosion resulting in property damage, severe personal
injury, or death.
2.4.3 Replacing an Existing Water Heater
If the water heater is to replace an existing water heater, check for and correct any
existing system problems such as:
System leaks
Location that could cause the system and water heater to freeze and leak
3 Water Quality Requirements
CAUTION:PROPERTY DAMAGE,PRODUCTDAMAGE
Chemical composition of the water supply may affect
efficiency and cause severe damage to the appliance and
associated equipment. Water quality must be professionally
analyzed to determine whether it is necessary to treat the
water. Various solutions are available to adjust water quality.
Adverse water quality will affect the reliability of the system.
In addition, operating temperatures above 135°F will
accelerate the build-up of lime scale and possibly shorten
appliance service life. Failure of an appliance due to lime
scale build-up, low pH, or other chemical imbalance IS NOT
covered by the warranty.
The water must be potable, free of corrosive chemicals, sand, dirt, and other
contaminates, and meet the manufacturer’s requirements. It is up to the installer
to ensure the water does not contain corrosive chemicals or elements that can
damage the heat exchanger. Potable water is defined as drinkable water supplied
from utility or well water in compliance with EPA secondary maximum contaminant
levels (40 CFR Part 143.3). If the water contains contaminants higher than
outlined by the EPA and the manufacturer, water treatment is recommended and
additional, more frequent maintenance may be required. If you suspect that your
water is contaminated in any way, discontinue use of the appliance and contact an
authorized technician or licensed professional.
Contaminant Maximum Allowable Level
pH 6.5 - 8.5
Total Dissolved Solids (TDS) Less than 500 mg/L
Free CO2 Less than 500 mg/L
Total Hardness Less than 200 mg/L
Aluminum Less than 0.2 mg/L
Chloride Less than 250 mg/L
Copper Less than 1.0 mg/L
Iron Less than 0.3 mg/L
Manganese Less than 0.05 mg/L
Zinc Less than 5 mg/L
Table 3 Water Quality Requirements
NOTICE:PRODUCTDAMAGE
Failure of electric elements due to lime scale build-up on the
heating surface, low pH, or other imbalance IS NOT covered
by the warranty.
Hard water, water containing mineral concentration of over
250 mg/liter, may cause a scale build up that can damage the product.
In case of hard water it is recommended to use an anti-scale treatment.
Damage caused by scale is not covered by the warranty.
To promote appliance service life, it is strongly recommended to follow
the maintenance procedures in this manual.

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4 Water Heater Components
Figure 2
12
34 5
67
9
10
12
14 16
1515
11
8
13
Water Heater Components
1Power Button
2Digital Temperature Display
3Temperature Setting Buttons
4LED Indicator
5Cold Water Intlet
6Hot Water Outlet
7Electrical Knockout/Strain Relief
8Inlet Water Filter
9Triac
10 Heating Canister
11 Heating Element
12 High Limit Switch
13 Terminal Block
14 Ground Connection
15 Thermistor
16 Flow Switch

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Bosch Tronic 6100 C Electric Tankless Water Heaters - BTC 724001301 A (08.2022)
5 Dimensions
Figure 3
13 1/4"
20 1/4" 5 1/8"
8 1/2" 6 1/16"
6 3/8"
Dimensions

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6 Technical Specifications
Description TR6100C-18 TR6100C-27
Wattage (kW)* 240V 18 27
208V 13.5 20
Max Amperage 240V 75 112.5
208V 65 96
Required Breaker(s) 208V/240V 3 x 30A Double Pole 3 x 40A Double Pole
Required Wire Size 208V/240V 3 x 10 AWG w/Ground 3 x 8 AWG w/Ground
Minimum Water Flow to Activate 0.5 gpm
Working Pressure 7 - 150 psi (0.5 - 10 bar)
Tested Pressure 290 psi (20 bar)
Water Connections 3/4” NPT
Heating Canisters with Internal Elements 2
Weight 12.2 lb (5.5 kg)
Temperature Range 86 - 125°F (30 - 52°C)
Table 4
* Performance will reduce if voltage reduces
TemperatureRise Δt Flow Rate (GPM)
TR6100C-18 TR6100C-27
35°F 3.51 5.26
45°F 2.73 4.09
77°F 1.59 2.39
Table 5

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7 Installation
7.1 Wall Mounting the Water Heater
1. Remove the 2 screws used for shipping on the backside of the unit and recycle.
They are no longer needed.
Figure 4
2. Remove 2 screws located on the bottom of the cover and save for reinstallation.
Figure 5
NOTICE:PRODUCTDAMAGE!
BEFORE PROCEEDING TO THE NEXT STEP, it is important
to know there is a wiring harness connected to the
backside of the front cover. This must be disconnected to
fully remove the cover. DO NOT pull cover out and away
completely without disconnecting wiring first or damage
may occur.
3. Pull bottom of cover forward and swing out (pos.1). Lift away from tabs on the
top of the back cover (pos.2). Do not fully remove cover.
Figure 6
1
2
2
2
4. Disconnect wiring harness connected to the inside of the front cover.
Figure 7
5. Remove cover completely.
6. Choose a suitable mounting surface that is solid and secure.
WARNING:ELECTRICSHOCK HAZARD
Do not install the unit above electrical boxes or junctions.

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7. The appliance must be mounted upright, with water inlets and outlets at the
bottom. See Figure 8.
WARNING:IMPROPEROPERATION, PERSONALINJURY, PRODUCT
DAMAGE
This water heater must be installed upright in the vertical
position as described in this manual. DO NOT attempt to
install this water heater in any other orientation. Doing so
will result in improper water heater operation and property
damage, and could result in serious personal injury or death.
Figure 8
DO NOT INSTALL UNIT UPSIDE DOWN, ON SIDE OR ON IT’S BACK
CORRECT
INCORRECT
8. Position the unit on the mounting surface. Ensure the unit is plumb.
9. Mount the unit to the wall with four (4) screws of at least one (1) inch
(25.4mm) in length at the marked points. See Figure 9.
Mounting screws not included with the product.
Figure 9
13" 3 7/8"3 7/8"
NOTICE:PROPERTY DAMAGE,PRODUCTDAMAGE
Use screws suitable for the wall material and the weight of
the water heater. Failure to do so could result in property
damages and damage to the water heater. Such damages
ARE NOT covered by the product warranty.
10. Pull gently on the water heater to ensure that it is properly mounted.

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7.2 Plumbing
It is mandatory that all plumbing be done in accordance with federal, local, and
state plumbing codes and practices. Failure to properly install the water heater
WILL VOID the warranty. It is also best practice to use thread tape on all mechanical
plumbing connections.
Do not apply thread tape on the first two threads. Keep clear to
prevent materials entering the water path.
1. Install unions on the hot and cold water connections to easily disconnect the
water heater for servicing. See Figure 10.
Before connecting pipes to the water heater, flush the lines to eliminate
all residue and debris from the inlet and outlet lines.
2. Connect the water inlet line to the entry point of the heater (right side inlet),
and connect the outlet line to the water outlet. Use a line that can withstand
a minimum pressure of 150 psi. Using any other type of line will cause
damage. All water pipes within three (3) feet of the unit’s water inlet and
outlet must be rated for high temperature applications of 185°F (85°C)
minimum.
NOTICE:PRODUCTDAMAGE
Do not solder any piping to the unit’s connection points.
If sweat connections are used, sweat tubing to the adapter
before fitting adapter to the water connections on the
heater. Any heat applied to the water heater connections will
permanently damage the water heater. Use two wrenches
when tightening water piping at heater. Use one wrench to
prevent the heater inlet or outlet line from turning. Take care
not to over tighten. Damages due to improper installation
practices ARE NOT covered by warranty.
The maximum operating water pressure of this water heater is 150 psi /
10 bar. Residential plumbing systems with unstable pressure or pressure
above 73 psi require the application of a pressure reducing valve, set to
58 - 73 psi.
NOTICE:PRODUCTDAMAGE
Failure of the water heater due to lime scale build-up on the
heating surface, low pH, or other imbalance IS NOT covered
by the warranty. See Section 3 Water Quality Requirements.
Minimum pipe size should match water heater connection.
The installer is responsible for all equipment and components required by
local codes. In Massachusetts, you must install a vacuum relief valve per
248 CMR. 4.
A temperature and pressure (T&P) relief valve is not required for most
installations, but may be required to meet local, state, or provincial codes.
If codes require a T&P valve, install according to code and manufacturer
instructions.
Mixing valve applications are recommended to help prevent scalding.
It is highly recommended by the manufacturer to install water leak
detection devices and automatic shutoff valves in any water heater
installation where a leakage of water could result in property damages.
7.2.1 Pressure Relief Valve
For protection against excessive pressures in this water heater,a pressure relief
valve (PRV) may be installed. Refer to local codes to see if the installation of a PRV
is required. Install the PRV (with a maximum set pressure of 150 psi) on the hot
outlet line of the water heater, and orient it or provide tubing so that any
discharge from the valve will exit at least 6” above the structural floor. The relief line
cannot be in contact with any live electrical parts. The discharge opening must not
be blocked or reduced in size under any circumstances.
Commonwealth of Massachusetts
As a condition of installing this product in the Commonwealth of Massachusetts a
pressure relief valve shall be installed on the hot water side, by a licensed plumber
MGL 142 Section 19. (Approval number: P1-09-25).
DANGER:PERSONAL INJURY,PROPERTYDAMAGE, PRODUCT
DAMAGE
Do not thread a cap or plug into a relief valve or relief valve
line under any circumstances! Explosion and property
damage, serious injury, or death may result.

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7.3 Installation Example
This drawing is meant to demonstrate system piping only.
Figure 10
COLD WATER INLET
HOT WATER OUTLET
CHECK VALVE BALL VALVE
AUTOMATIC WATER
SHUT-OFF VALVE
UNION
WATER LEAK
DETECTION
SENSOR
DRAIN
PRESSURE RELIEF
VALVE (IF REQUIRED
BY LOCAL CODE)

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Bosch Tronic 6100 C Electric Tankless Water Heaters - BTC 724001301 A (08.2022)
7.5 Scalding
WARNING:SCALDHAZARD
An ASSE 1017 or ASSE 1070 temperature limiting or
mixing valve is recommended in installations servicing
disabled or elderly persons, or children. Mixing valves do
not eliminate the risk of scalding. To avoid scalding:
—Set the water heater set point temperature as low as
possible.
—Feel water before bathing or showering.
—If thermostatic valves are required, use devices
specifically designed for such purpose. Install these
devices in accordance with instructions provided by
the manufacturer.
Failure to install a temperature limiting or mixing valve and
follow these instructions could result in property damage,
severe personal injury, or death due to scalds.
This water heater can deliver scalding water. Be careful whenever using hot water
to avoid scalding injury. Certain appliances such as dishwashers and automatic
clothes washers may require increased water temperatures. By setting the
thermostat on this heater to obtain the increased water temperature required by
these appliances you may create the potential for scald injury.
To protect against injury, install a mixing valve in the water system. This valve will
reduce point of use discharge temperatures by mixing cold and hot water in branch
supply lines. Such valves are available from your local plumbing supplier.
Table 1 details the relationship of water temperature and time with regard to scald
injury and may be used as a guide in determining the safest water temperature for
your applications.
7.6 Filling the Heater
1. Make certain any drain valves in the system are completely closed.
2. Open the shut-off valve in the cold water supply line.
3. Open the hot water faucets to allow air to vent from the heater and piping.
4. Allow sufficient time for the heater to completely fill with water.
5. Check for and repair any leaks.
If you detect a water leak from the water heater at this point, turn off
the water supply at the main shut-off valve and contact Customer Service
(Phone: [phone]).
NOTICE:PRODUCTDAMAGE, PROPERTY DAMAGE
When filling the water heater, open a hot water tap to release
air in the water heater and piping. The heating canisters
must be full of water before the heater is turned on. Failure
to ensure the water heater is full before turning it on could
result in damage to the water heater and other property
damages. Such damages ARE NOT covered by water heater
warranty.

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Installation Manual
Bosch Tronic 6100 C Electric Tankless Water Heaters- BTC 724001301 A (08.2022)
7.7 Electrical Connection
DANGER:HAZARDOUS VOLTAGE
Failure to disconnect the power from the water heater
before attempting to install or repair it will result in property
damage, severe personal injury, or death.
WARNING:PERSONALINJURY, PROPERTY DAMAGE
All wiring (wire gauge) as well as circuit protection
(breakers) must comply with the National Electrical
Code (NEC) in the USA and done by a qualified licensed
electrician or the local electric utility.
WARNING:ELECTRICSHOCK HAZARD
Be sure to ground the water heater. Failure to do so could
result in property damage, severe personal injury, or death.
NOTICE:PRODUCTDAMAGE, PROPERTY DAMAGE
The water heater must be full of water before the power is
turned on. The heating element will be damaged if energized
for even a short time while heating canister is dry. Failures
due to “dry-firing” ARE NOT covered by warranty.
This water heater must be installed in accordance with all applicable
local, state, provincial, and national electrical codes.
The heater must be connected to dedicated circuit breakers.
18 - 27kW models require 3 sets of wires and ground. See Wiring
Diagrams for additional information.
1. Take each wire pair and connect them to one breaker (see Wiring Diagrams).
Ensure that each breaker is connected to one black wire and one red or white
wire. Ensure the power to the unit is shut off by means of the dedicated
circuit breakers in the main electrical panel.
2. A suitable wire gauge which meets all applicable electrical codes for the
size of the breakers should be used. The correct set of power cable wires
should be run from the circuit breakers in the main electrical panel to the
water heater. Connect the power cable to the terminal block within the water
heater.
3. Each incoming circuit requires a separate ground connector.
4. DOUBLE CHECK the electrical connections to ensure their correctness as
well as the tightness and secureness of wire connections. Its important to
confirm that the correct breaker size and wire gauge has been used and
that the unit has been connected to a ground in accordance with applicable
codes.
Ensure that all connections are correctly made to ensure proper
operation of the unit. It is critical that the unit be wired as shown.
Mixing up one set of wires with another will result in the failure of
the unit to operate correctly even though it turns on and otherwise
appears to function properly.
5. The front cover of the unit should be replaced and reattached with two (2)
screws.
6. Ensure that all the air has been purged from the water lines before turning on
power to the unit. Kindly check STEP 3 in the plumbing installation section.
Restore power to the unit by means of the dedicated circuit breakers in the
main electrical panel.

18 |
Installation Manual
Bosch Tronic 6100 C Electric Tankless Water Heaters - BTC 724001301 A (08.2022)
7.8 Wiring Diagrams
7.8.1 Power Supply Wiring for 18 and 27kW
Figure 11
Terminal Block in Unit
L1 L2
V042
V042
V042
Unit requires 10 AWG for 18kW, 8 AWG for 27kW wire with ground - one for each 240 V circuit.
L1 L2 L1 L2
L1 L2 L1 L2 L1 L2
Grounding Block in Unit
Internal PCB Dip Switches
The internal PCB dip switch #4 can be moved to switch between Fahrenheit and
Celsius on the external display. See Figure 12. No other dip switches should be
altered.
WARNING:ELECTRICALHAZARD
Before changing the dip switch setting all power to the
water heater must be turned off at the circuit breakers
otherwise the setting change will not be activated.
NOTICE:PRODUCTDAMAGE
Do not alter or change the position of dip switches #1,#2 or
#3. These are used for factory programming.
Dip switch #4 may be adjusted to set display to °C.
Figure 12
1234
ON DIP
DO NOT
CHANGE
POSITION OF
DIP SWITCHES
USE DIP SWITCH
#4 TO SWITCH
BETWEEN
FAHRENHEIT
AND CELSIUS
FAHRENHEIT = ON
CELSIUS = OFF

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Installation Manual
Bosch Tronic 6100 C Electric Tankless Water Heaters- BTC 724001301 A (08.2022)
7.8.2 Internal Wiring Diagram for 18kW
Figure 13
L1
THERMOSTAT 1
G
TRIAC 1
PE(G)
Bottom Plate
L1
THERMOSTAT 2
G
TRIAC 2 H.E 2
G
TRIAC 3 H.E 3
PCBA CNTRL1 -HEATER CONTROL UNIT
HEATER DISPLAY
SEN1- FLOW SENSOR
SEN2- IN TEMP. SENSOR
SEN3- OUT TEMP. SENSOR
H.E 1
L1
THERMOSTAT 3
Auto 60 Auto 60 Auto 60
L2 L2
L2

20 |
Installation Manual
Bosch Tronic 6100 C Electric Tankless Water Heaters - BTC 724001301 A (08.2022)
7.8.3 Internal Wiring Diagram for 27kW
Figure 14
L1
THERMOSTAT 1
G
TRIAC 1
PE(G)
Bottom Plate
L1
THERMOSTAT 2
G
TRIAC 2
H.E 2
G
TRIAC 3
H.E 3
PCBA CNTRL1 -HEATER CONTROL UNIT
HEATER DISPLAY
SEN1- FLOW SENSOR
SEN2- IN TEMP. SENSOR
SEN3- OUT TEMP. SENSOR
H.E 1
L1
THERMOSTAT 3
Auto 60 Auto 60 Auto 60
L2 L2
L2
Manual 85
THERMOSTAT 4
Manual 85
THERMOSTAT 5