Bosch C1210ES User manual

6 720 644 887 (2022/04) US
Installation and Operating Instructions
INDOOR RESIDENTIAL AND COMMERCIAL MODELS
C 1210 ES/ESC
WARNING!
Improper installation, adjustment, alteration, service or maintenance can cause
injury or property damage. Refer to this manual. For assistance or additional infor-
mation consult a qualified installer, service agency or the gas supplier.
NOTICE
Upon completion of the installation, these instructions should be handed to the
user of the appliance for future reference.
C 1210 ES/ESC - Natural Gas / C 1210 ES/ESC - Liquefied Petroleum (LP) Gas

Table of contents
C 1210ES/ESC – 6 720 644 887 (2022/04)
2
Table of contents
1 Key to symbols and safety instructions . . . . . . . . . . . . .3
1.1 Key to symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.2 Safety instructions. . . . . . . . . . . . . . . . . . . . . . . . . . .3
2 FCC rules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
3 Appliance details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
3.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
3.2 Specifications (Technical data). . . . . . . . . . . . . . . 10
3.3 Unpacking the heater. . . . . . . . . . . . . . . . . . . . . . . 12
3.4 General rules to follow for safe operation. . . . . . . 13
3.5 Dimensions and minimum installation
clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4 Installation instructions . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 Specialized tools . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3 Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.4 Combustion air requirements . . . . . . . . . . . . . . . . 33
4.5 Proper location for installing your heater . . . . . . . 33
4.6 Heater placement and clearances. . . . . . . . . . . . . 34
4.7 Mounting installation . . . . . . . . . . . . . . . . . . . . . . . 34
4.8 Gas piping & connections . . . . . . . . . . . . . . . . . . . 35
4.8.1 Gas Line Sizing Tables for NATURAL GAS . . . . . . 37
4.8.2 Gas Line Sizing Tables for LP GAS . . . . . . . . . . . . 38
4.9 Water connections. . . . . . . . . . . . . . . . . . . . . . . . . 39
4.10 Water quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.11 Filling the condensate trap . . . . . . . . . . . . . . . . . . 40
4.12 Domestic hot water recirculation . . . . . . . . . . . . . 42
4.13 Space heating applications . . . . . . . . . . . . . . . . . . 42
4.14 Measuring gas pressure. . . . . . . . . . . . . . . . . . . . . 44
5 Electrical connections. . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.1 Electrical power supply . . . . . . . . . . . . . . . . . . . . . 46
5.2 Position of the fuses in control unit. . . . . . . . . . . . 46
6 Operation instructions . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.1 Description LCD Display . . . . . . . . . . . . . . . . . . . . 47
6.2 For your safety read before operating your
water heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.3 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.4 Temperature selection. . . . . . . . . . . . . . . . . . . . . . 48
6.5 Proper location for installing your heater . . . . . . . 49
6.6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6.7 Reset button. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6.8 Program button . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
6.9 Locked condition . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7 Maintenance and service . . . . . . . . . . . . . . . . . . . . . . . 50
7.1 Annual maintenance . . . . . . . . . . . . . . . . . . . . . . . 50
7.2 Winterizing for seasonal use . . . . . . . . . . . . . . . . . 51
7.3 Mineral scale build-up . . . . . . . . . . . . . . . . . . . . . . 51
7.4 Condensing heat exchanger unit. . . . . . . . . . . . . . 52
7.5 Adjusting CO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
7.6 Program values . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.7 Control board diagnostics. . . . . . . . . . . . . . . . . . . 56
8 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.2 Burner does not ignite when hot water is
turned ON. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.3 Water is too hot . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.4 Water is not hot enough. . . . . . . . . . . . . . . . . . . . . 58
8.5 Low water flow/pressure. . . . . . . . . . . . . . . . . . . . 58
8.6 Hot water temperature fluctuates at tap. . . . . . . . 58
8.7 Noisy burner/heater during operation . . . . . . . . . 59
9 Problem solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.1 Error code diagnostics . . . . . . . . . . . . . . . . . . . . . 60
10 Electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
11 Sensor resistance charts . . . . . . . . . . . . . . . . . . . . . . . 65
13 Interior components diagram and parts list . . . . . . . 69
13 Interior components diagram and parts list . . . . . . . 69
14 Protecting the environment. . . . . . . . . . . . . . . . . . . . . 83
15 Installer Checklist to be completed by installer
upon installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Key to symbols and safety instructions
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1 Key to symbols and safety instructions
1.1 Key to symbols
Warnings
In warnings, signal words at the beginning of a warning are used
to indicate the type and seriousness of the ensuing risk if
measures for minimising danger are not taken.
The following signal words are defined and can be used in this
document:
DANGER:
DANGER indicates a hazardous situation which, if not avoided,
will result in death or serious injury.
WARNING:
WARNING indicates a hazardous situation which, if not
avoided, could result in death or serious injury.
CAUTION:
CAUTION indicates a hazardous situation which, ifnot avoided,
could result in minor or moderate injury.
NOTICE:
NOTICE is used to address practices not related to personal
injury.
Important information
The info symbol indicates important information where there is
no risk to people or property.
Additional symbols
Table 1
1.2 Safety instructions
HWARNING:
Before installation,
▶ Read all instructions before installing.
Perform the steps in the indicated
sequence.
▶ Have the water heater inspected by a
trained service technician at least
once every year.
▶ Failure to comply with these
instructions can result in severe,
possibly fatal, personal injury as well
as damage to property and
equipment.
HDANGER:
Installation and servicing.
Risk of fire when soldering and
brazing!
▶ Takeappropriate protectivemeasures
when soldering and brazing around
combustible and flammable material.
▶ Ensure that only a licensed contractor
installs or services the water heater.
▶ On hot components use only material
with adequate temperature stability.
HWARNING:
Installation and commissioning.
▶ Do not install this device in rooms
with a high moisture level
(e.g. bathrooms, saunas).
Symbol Meaning
▶ a step in an action sequence
a reference to a related part in the document
•alistentry
–a list entry (second level)

Key to symbols and safety instructions
C 1210ES/ESC – 6 720 644 887 (2022/04)
4
HWARNING:
▶ To ensure that the water heater
functions properly, follow these
installation and maintenance
instructions.
▶ Never close the blow-off line of the
pressure safety valve. For safety
reasons, water may escape during
heating.
HDANGER:
Risk of explosion!
If you smell gas.
▶ Turn off the gas shut-off valve.
▶ Open windows and doors.
▶ Do not try to light the appliance.
▶ Do not touch any electrical switch,
telephone, and do not use outlets.
▶ Extinguish all open flames. Do not
smoke! Do not use lighters!
▶ Warn all occupants of the building. Do
not ring doorbells!
▶ If you can hear gas leaking, leave the
building immediately.
▶ Prevent others from entering the
building and notify the police and fire
department from outside the
building.
▶ From outside the building, call thegas
utility company and a trained and
certified installer.
HDANGER:
If you smell flue gas,
▶ Switch off the appliance.
▶ Open windows and doors.
▶ Inform the certified installer who
installed the appliance.
HDANGER:
Risk of poisoning!
Insufficient ventilation may cause
toxic flue gas to escape.
▶ Never close off or reduce the size of
the air intake and outlet openings.
▶ The appliance must not be operated
until any obstructions have been
removed.
▶ Inform the customer of the problem
and the associated dangers.
HDANGER:
Danger from escaping flue gases.
▶ Ensure all vent pipes and chimneys
are not damaged or blocked.
▶ Connect only one appliance to each
vent system or chimney liner.
▶ The venting system piping must not
feed into another air extraction duct.
▶ Do not route the flue system piping
through or inside another air
extraction duct.
HDANGER:
Danger of explosion of flammable
gases.
▶ Work on gas components may only be
carried out by a trained and certified
installer.

Key to symbols and safety instructions
5
C 1210ES/ESC – 6 720 644 887 (2022/04)
▶ Installation, gas and flue connection,
initial commissioning, electrical
connections and annual maintenance
must only be carried out by a trained
and certified installer.
HCAUTION:
Combustion air.
▶ Keep the combustion air free of
corrosive substances (halogenated
hydrocarbons that contain chlorine or
fluorine compounds).
HWARNING:
Never shut off safety valves!
▶ Water may escape from the safety
valve at any time when the water is
being heated.
HWARNING:
Inspection/maintenance
▶ Servicing and repairs may only be
carried out by a trained and certified
installer.
▶ Immediately correct all faults to
prevent system damage.
▶ Use only Bosch spare parts!
HCAUTION:
Instruct the customer.
▶ Explain to the customer how the
appliance works and how to operate
it.
▶ Inform the customer that he/she must
not carry out any alterations or
repairs.
HDANGER:
Risk of electric shock!
▶ Ensure that only an authorized
contractor performs electrical work.
▶ Before performing electrical work,
disconnect the power and secure the
unit against unintentional
reconnection.
▶ Ensure the system has been
disconnected from the power supply.
HDANGER:
Risk of scalding at the hot water
fixture!
▶ Whenthe waterheateris in operation,
temperatures in excess of 122 °F
(50 °C) can occur. To limit the
temperature at the tap, install a
thermostatic DHW mixing valve.
▶ Water heated for washing the laundry,
dishes and for other cleaning
purposes can cause scalding and
permanent injuries.
▶ Children, disable and elderly are at
highest risk of being scalded. Never
leave such individuals in the tub or
shower unattended under any
circumstances. Children must not be
allowed to operate hot water faucets
themselves.

Key to symbols and safety instructions
C 1210ES/ESC – 6 720 644 887 (2022/04)
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▶ If the building has occupants in the
above groups who operate hot water
faucets, or state laws / local
ordinances stipulate specific water
temperatures, take the following
precautions:
– Use the lowest possible
temperature setting.
– To prevent scalding, install a
tempering device, such as an
automatic mixing valve, at hot
water tap or water heater. Select
and install the automatic mixing
valve in accordance with the valve
manufacturer's recommendations
and instructions.
▶ Water exiting from drain valves can be
extremely hot. To avoid injuries:
– Check that all connections are
tight.
– Direct exiting water away from
people.
▶ Measures must be taken to protect
against excessive temperature and
pressure! Installation of a T&P safety
valve is required.
HWARNING:
Electrical safety.
To protect against corrosion and ensure
compliance with the rules for electrical
safety, observe the following points:
▶ Use metal fittings for potable water
heating systems with plastic piping.
▶ Use only original accessories from the
manufacturer.
▶ When installation of the water heater
is complete, inspect and confirm
proper ground conductor.
HCAUTION:
Maintenance
▶ Inspect and maintain the water heater
on a yearly basis. Service as needed.
▶ See chapter 7.1.
▶ Use only genuine spare parts.
HWARNING:
Flooding
▶ After a flood, do not use the appliance
if any part has been submerged.
Damage to appliances that have been
submerged can be quite severe and
pose numerous safety risks.
▶ Every appliance that has been
submerged must be replaced.
HWARNING:
Risk of explosion!
For your safety
▶ Do not store or use gasoline or other
flammable, combustible or corrosive
vapors and liquids in the vicinity of
this or any other appliance.

Key to symbols and safety instructions
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C 1210ES/ESC – 6 720 644 887 (2022/04)
DANGER:
Fatal accidents!
Carbon monoxide poisoning.
▶ Carefully plan where you install the heater. Correct
combustion air supply and flue pipe installation are very
important. If a gas appliance is not installed correctly, fatal
accidents can result such as carbon monoxide poisoning or
fire.
DANGER:
Carbon monoxide poisoning.
▶ Exhaust gas must be vented to outside using approved vent
material. See table 5, page 16 (In Canada use only
ULCS636 approved material). Vent and combustion air
connector piping must be sealed gas-tight to prevent flue
gas spillage, carbon monoxide emissions and risk of fire,
resulting in severe personal injury or death. Approved vent
terminations must be used when penetrating to the
outside.
DANGER:
Electric shock!
▶ Field wiring connections and electrical grounding must
comply with local codes, or in the absence of local codes,
with the latest edition of the National Electric Code, ANSI/
NFPA 70, or in Canada, all electrical wiring must comply
with the local codes and the Canadian Electrical Code, CSA
C22.1 Part 1.
DANGER:
Electric shock!
Shock hazard: line voltage is present.
▶ Before servicing the water heater, unplug power supply
cord from outlet. Failure to do so could result in severe
personal injury or death.
WARNING:
Damage to the appliance from over pressure.
▶ The heater must be disconnected from the gas supply
piping system during any pressure testing of that system at
test pressures equal to or more than 0.5 psi.
NOTICE:
▶ The appliance should be located in an area where leakage of
the heater or connections will not result in damage to the
area adjacent to the appliance or to lower floors of the
structure. When such locations cannot be avoided, it is
recommended that a suitable drain pan, adequately
drained, be installed under the appliance. The pan must not
restrict combustion air flow.
WARNING:
▶ The maximum inlet gas pressure must not exceed the value
specified by the manufacturer and the minimum value
listed is for the purpose of input adjustment.
NOTICE:
▶ If a water heater is installed in a closed water supply
system, such as one having a backflow preventer in the cold
water supply line, means shall be provided to control
thermal expansion. Contact the water supplier or local
plumbing inspector on how to control this situation.
WARNING:
Fire danger!
▶ Keep appliance area clear and free from combustible
materials, gasoline and other flammable vapors and
liquids.
NOTICE:
▶ Do not obstruct the flow of combustion and ventilation air.
NOTICE:
Appliance malfunction!
▶ If power is lost while appliance is operating. Turn off both
water and power for 15 seconds to reset device.

FCC rules
C 1210ES/ESC – 6 720 644 887 (2022/04)
8
WARNING:
Risk of scalding and property damage.
▶ Precautions must be taken prior to manually operating the
relief valve to avoid contact with hot water discharged from
the relief valve and to prevent water damage.
NOTICE:
Appliance damage!
▶ Label all wires prior to disconnection when servicing
controls. Wiring errors can result in improper and
dangerous operation. Verify proper operation after
servicing.
WARNING:
System damage!
▶ If a relief valve discharges periodically, this may be due to
thermal expansion in a closed water supply system.
Contact the water supplier or local plumbing inspector on
how to correct this situation. Do not plug the relief valve.
WARNING:
Property damage!
▶ If the water heater is used in a space heating application, all
piping and components connected to the water heater
must be suitable for use with potable water.
WARNING:
Personal Injury from toxic chemicals.
▶ Toxic chemicals, such as those used for boiler treatment,
shall not be introduced into the potable water used for
space heating.
WARNING:
Personal Injury from toxic chemicals.
▶ A water heater which will be used to supply potable water
shall not be connected to any heating system or
component(s) previously used with a nonpotable water
heating appliance.
2FCCrules
FCC:This device complies with Part 15 of the FCC rules.
Operation is subject to the following two conditions: (1) This
device may not cause harmful interference, and (2) this device
must accept any interference received, including interference
that may cause undesired operation.
Fig. 1
The chart below shows the relationship between water
temperature and time until there is a risk of scalding. It can be
used as the basis for determining the safest water temperature
for your application.
Temperature Time to severe scalding1)
120 °F (48 °C) longer 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

Appliance details
9
C 1210ES/ESC – 6 720 644 887 (2022/04)
Table 2 Approximate time-temperature relationship until
there is a risk of scalding
WARNING:
This product can expose you to chemicals including lead, which
is 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.
BOSCH water heater complies with the State of California Lead
Law (AB1953).
3 Appliance details
3.1 Features
Residential / Commercial models
• C 1210 ES residential model
– maximum temperature 140 °F
• C 1210 ESC commercial model
– maximum temperature 180 °F
Parts
•KeyPadinterfacecontrol.
• High power pre-mix compact burner with low NOx
emissions.
•ModulatingGasValvewithconstant gas:air ratio control.
•Modulatingwatervalveforimprovedcomfortand
temperature control.
High quality materials for long working life
• Copper heat exchanger.
• High efficiency Ceramat Burner.
• Compact space saver: mounts on a wall with a supplied
bracket.
Features
• Easily removable one-piece cover.
• LCD Display with backlight.
• On/Off and Temperature control buttons.
•Resetbutton.
• Program button (Selectable temperature default).
• Failure codes for easy diagnostics and repair.
• Real-time diagnostics for troubleshooting/informational
purposes.
• Built in freeze prevention.
Note: The freeze prevention kit is designed to provide
protection for the water heater down to approximately 5°F for
short term conditions only. It will not protect the appliance in
areas where the temperature is routinely expected to be below
freezing.
- The freeze prevention kit will not protect plumbing outside the
appliance from freezing. Precautions should be taken.
Accessories (Bosch part #)
• Concentric termination kit 3"/ 5"PVC (196006)
• Concentric vent kit 80/125 PP (7738003210)
• Concentric Up and Out kit (7 738 003 210)
• Neutralizer Kit (7738001483)
• Isolation Valve Kit (7738003449)
• Optional wireless remote control to operate with the
appliance (TSTAT2)
• Cascading kit (7709003962)
• External water filter (part # 8 703 305 356)
• Concentric termination kit 3"/6" PVC (196016)
• Exhaust/Intake bird screen (L2594)
• Condensate drain tee (196061) [included with Concentric
termination kits]
• Pipe Cover (PTPCES)
• High temperature kit (7736500074)
• Recess box kit (7736500043)
• Pressure relief valve 150 PSI (7738001152)
BOSCH is constantly improving its products, therefore
specifications are subject to change without prior notice.
1) Source: Moritz, A.R. and Henriques, F.C., Jr. (1947).
Studies of thermal injury. II. The relative importance of time
and surface temperature in the causation of cutaneous
burns, Am J of Pathol, 23, 695-720.

Appliance details
C 1210ES/ESC – 6 720 644 887 (2022/04)
10
3.2 Specifications (Technical data)
Approved in US/Canada
Technical characteristics Units C 1210 ES/ESC
Capacity
Maximum flow rate at a 45 °F (25 °C) rise GPM (l/min) 9.2 (35)
Maximum flow rate at a 63 °F (35 °C) rise GPM (l/min) 6.6 (25)
Maximum flow rate at a 99 °F (55 °C) rise GPM (l/min) 4.2 (16)
Maximum flow rate at a 135 °F (75 °C) rise GPM (l/min) 3.1 (12)
Maximum flow rate at a 162 °F (90 °C) rise GPM (l/min) 2.6 (10)
Maximum output BTU/hr (kW) 210,000 (61.5)
Maximum input BTU/hr (kW) 225,000 (65.9)
Thermal efficiency (Efficiency in %) % > 94%
Minimum Input BTU/hr (kW) 25,000 (7.3)
Temperature Control
C 1210 ES - Selection range °F ( °C) 100 - 140 (38) - (60)
C 1210 ESC - Selection range °F ( °C) 100 - 180 (38) - (82)
Default temperature °F ( °C) 122 (50)
Stability °F ( °C) ± 2 (± 1)
Gas Requirement
Gas connection inches ¾"
Inlet gas pressure under operation (with a high hot water flow rate)1)
Propane water column 8” - 13”
Natural Gas water column 3.5” - 10.5”
Water
Hot water connection inches ¾"
Cold water connection inches ¾"
Minimum water flow2) GPM (l/min) 0.5 (1.9)
Minimum recommended water pressure PSI (bar) 30 (2.07)
Minimum well pressure PSI 40
Water valve material Polymer (PPS) (Polypropylene Sulfide)
Connections: Bottom of heater
Combustion
CO level ppm ≤ 290 (measured)
CO2level (set from factory) % see table 34
Dimensions
Depth inches (mm) 11 ¼ (286)
Width inches (mm) 17 7/8(452)
Height inches (mm) 30½ (775)
Weight pounds (kg) 74 (33.5)
Gas types
Natural Gas
LP Gas
Voltage

Appliance details
11
C 1210ES/ESC – 6 720 644 887 (2022/04)
Table 3
If appliance is installed at elevations above 2000ft, refer to
chapter 4.3.7 Fan speed adjustment.
Safety devices
• Flame failure device (ionization flame rod sensor)
• Overheat prevention (temperature limiter/ECO)
• Inlet temperature sensor
• Outlet temperature sensor
• Back flow temperature sensor
• Exhaust gas temperature sensor
Tension V AC 120
Frequency Hz 60
Amperage
Idle mA 40
Operation A ≤ 2.5
Noise db (A) 45 - 65
Water protection3) IP X4D
1) To measure Gas Pressure, see Measuring Gas Pressure, chapter 4.14, page 44.
2) Activation varies with inlet water temperatures from 0.5 - 1.6 gallon/minute (1.9 - 6.1 l/m).
3) Protection against water drops.
Technical characteristics Units C 1210 ES/ESC

Appliance details
C 1210ES/ESC – 6 720 644 887 (2022/04)
12
3.3 Unpacking the heater
Before installing the unit, be certain you have the correct
heater for your type of Gas - Propane or Natural Gas.
Identification labels are found on the shipping box, and on the
rating plate which is located on the right side panel of the cover.
Fig. 2 Rating plate
[1] Serial number
[2] Type of gas
3.3.1 The box includes
• C 1210 ES/ESC
• Bracket for wall hanging the heater
• Exhaust vent adaptor (with 4 screws and gasket provided)
• Combustion air inlet adaptor (with 3 screws and gasket
provided)
• Installation manual (manual can be downloaded at
www.boschheatingandcooling.com)
• Product registration card
•EnergyGuidelabel
Please complete and return the enclosed product registration
card.
The C 1210 ES/ESC is not approved or designed for:
•Manufactured (mobile) homes, boats or any mobile
installation. (Modular homes are acceptable for
installation).
•Use above 8000 ft A.S.L. altitude (see page 29).
•Outdoor installations.
•Applications where inlet water temperature is higher
than 140°F (60°C). A 3-way valve or mixing valve must
be installed before the appliance if inlet water
temperature exceeds this limit.
3.3.2 Remove front cover
▶ Loosen the two Phillips head screws located on bottom rear
of cover.
Fig. 3 Loosen the two screws
▶ Lift front cover panel upward and remove.
Fig. 4 Remove the front cover

Appliance details
13
C 1210ES/ESC – 6 720 644 887 (2022/04)
3.3.3 Remove combustion cover (service only; unplug
appliance before removing cover)
▶ Open the four clips and remove the combustion cover.
Fig. 5 Remove the combustion cover
3.4 General rules to follow for safe operation
•1. You must follow these instructions when you install your
heater. In the United States: The installation must conform
with local codes or, in the absence of local codes, the
National Fuel Gas Code ANSI Z223.1/NFPA 54.
In Canada: The Installation must conform with CSA
B149.(1,2) INSTALLATION CODES and /or local
installation codes.
•2. Carefully plan where you install the heater. Correct
combustion air supply and vent pipe installation are very
important. If not installed correctly, fatal accidents can
occur, such as carbon monoxide poisoning or fire.
•3. When the unit is installed indoors and ROOM SEALED
(twin pipe) it is permitted to be located in bathrooms,
bedrooms and occupied rooms that are normally kept
closed. See chapter 4.3 (page 15). If the unit will be
installed indoors and use indoor combustion air, the place
where you install the heater must have enough ventilation.
The National Fuel Gas Codes do not allow UNSEALED
gas fired water heater installations in bathrooms,
bedrooms or any occupied rooms normally kept closed.
See chapter 4.4 (page 33).
•4. You must correctly vent your heater. See chapter 4.3
(page 15) on VENTING.
•5. The appliance and its gas connection must be leak tested
before placing the appliance in operation.
The appliance must be isolated from the gas supply piping
system by closing its individual manual gas shutoff valve
(not supplied with heater) during any pressure testing at
pressures in excess of ½ Psig (3.5 kPa).
•6. Keep water heater area clear and free from combustibles
and flammable liquids. Do not locate the heater over any
material which might burn.
•7. Correct gas pressure is critical for the proper operation
of this heater. Gas piping must be sized to provide the
required pressure at the maximum output of the heater,
while all the other gas appliances are in operation. Check
with your local gas supplier, and see the section on
connecting the gas supply. See chapter 4.8 (page 35).
•8. Should overheating occur or the gas supply fail to shut
off, turn off the gas supply at the manual gas shut off valve,
on the gas line. Note: manual gas shutoff valve is not
supplied with the heater but must be field installed.
•9. Do not use this appliance if any part has been
underwater. Immediately call a qualified service technician
to inspect the appliance and to replace any part of the
control system and any gas control which has been
underwater.
•10. Failure to install heater correctly may lead to unsafe
operation and void the warranty.
6720644956-11.1V

Appliance details
C 1210ES/ESC – 6 720 644 887 (2022/04)
14
3.5 Dimensions and minimum installation clearances
Fig. 6 Dimensions
[1] On/Off button
[2] Reset button
[3] Program key
[4] Power ON or stand-by LED
[5] LCD display
[6] Up button
[7] Down button

Installation instructions
15
C 1210ES/ESC – 6 720 644 887 (2022/04)
Fig. 7 Side view
For servicing access, a 2ft clearance is recommended to the
front cover.
Table 4 Minimum clearances
4 Installation instructions
4.1 Specialized tools
The following specialized tools may be required for installation:
•Manometer
•Multi-meter
• Combustion Gas Analyzer
4.2 Introduction
Please follow these instructions. Failure to follow
instructions may result in:
▶Damageorinjury.
▶Improperoperation.
▶ Loss of warranty.
WARNING:
▶ The water heater must be installed by a qualified installer in
accordance with these instructions. If improperly installed,
a hazardous condition such as explosion or carbon
monoxide poisoning could result. Bosch
Thermotechnology Corp. is not responsible for improperly
installed appliances.
Common installation practice is to first determine the venting/
combustion air point of termination, then design the piping
layout back to the heater.
4.3 Venting
NOTICE:
▶ Do not reduce the exhaust or combustion air vent pipe
sizes.
▶ Do not common vent with any other vented appliance or
stove.
▶ Do not use Type-B vent as the actual exhaust vent system
for the appliance.
WARNING:
▶ Failure to vent the exhaust gases to the outside (see table 3
for proper material) may result in dangerous flue gases
filling the structure in which it is installed.
Model C 1210 ES/ESC
TOP (A) 12”
FRONT (B) 1”
BACK 0”
SIDES 1”
FLOOR (C) 12”

Installation instructions
C 1210ES/ESC – 6 720 644 887 (2022/04)
16
WARNING:
▶ In areas where outside temperatures routinely come close
to freezing, sealed combustion operation is required.
Concentric termination or separate terminations for
combustion and vent, must be installed on the same wall or
roof surface; however, never facing the direction of
prevailing winds. Failure to do so may result in heat
exchanger freezing and bursting. This failure is not covered
under the manufacturer's warranty.
WARNING:
▶ Protect the exhaust and inlet from leaves and debris by
installing a screen on the end of the termination. ¼
" mesh minimum opening recommended on screen.
4.3.1 Vent material
This appliance can be installed as direct vent or Category IV.
All combustion air and vent pipe materials and fittings must
comply with the following:
Table 5 Approved vent material
For specific questions concerning vent material,
specifications, usage or installation, please contact the
vent manufacturer directly.
The use of cellular core PVC (ASTM F891), cellular core CPVC,
or Radel® (polyphenolsulfone) in non-metallic venting systems
is prohibited.
▶ Do not cover non-metallic vent pipe and fittings with
thermal insulation, unless going through an insulated
space.
All vent connections must be glued, except for the exhaust
accessory (chapter 4.3.4) which is screwed into place on
the top of the appliance. Slide the vent pipe into the exhaust
accessory. The exhaust pipe must be properly supported and
must be pitched a minimum of a ¼ inch per foot back to the
appliance. This allows the condensate to drain properly.
An optional concentric vent/air intake termination can be used
for the installation of a vertical or horizontal venting system.
(see fig. 8).
The concentric vent/air intake body can be ordered from your
local wholesaler. Part# 196016 (3"/6") and Part #196006
(3"/5").
The appliance can also be installed with separate air intake and
exhaust piping (see fig. 11, fig. 20 and fig. 21, page 27).
Table 6 Concentric vent part breakdown
Item Material United States Canada
Vent
or
air
pipe
and
fitting
PP concentric UL1738 ULC-
S636
certified
only
PP common vent UL1738
PP twin pipe UL1738
PVC schedule 40 ANSI/ASTM D1785
PVC-DWV ANSI/ASTM D2665
CPVC schedule 40 ANSI/ASTM F441
ABS-DWV schedule ANSI/ASTM D2661
Pipe
cement
/primer
PVC ANSI/ASTM D2564
CPVC ANSI/ASTM F493
ABS ANSI/ASTM D2235
Description Length Kit part
no. and
quantity
196016
3- In. Rain Cap N/A 1
4- In. Diameter SDR-26 Pipe 24 In. long 1
3- In. Y
Concentric Fitting
N/A 1
2- ½ In. Diameter SDR-26 Pipe 37-1/8 in.
long
1
3- In. Condensate drain Tee N/A 1
1.5- In. Condensate drain bushing N/A 1

Installation instructions
17
C 1210ES/ESC – 6 720 644 887 (2022/04)
Fig. 8 Concentric vent kit example
[1] Exhaust
[2] Combustion air
[3] Roof boot/flashing (field supplied)
[4] Exhaust pipe
[5] Drain tee 196061, included in concentric vent kits
[6] Intake pipe
[7] Concentric vent kit (196016)
[8] Maintain 12 in. (18 in. for Canada) minimum clearance
above highest anticipated snow level maximum of 24 in.
above roof
4.3.2 Vent specifications
An improperly sized venting system may lead to undesired
effects such as the formation of condensate, gas leakage or
spillage.
Establish vent clearances that comply with the vent
manufacturer's specifications and all applicable national/local
codes.
Venting specifications
Table 7 Venting specifications for intake and exhaust
[1] ULC S636-95, UL1738 certified
Vent termination
The vent for this appliance shall not terminate:
• over public walkways; or
• near soffit vents or crawl space vents or other areas where
condensate or vapor could create a nuisance or hazard or
cause property damage; or
• where condensate vapor could cause damage or could be
detrimental to the operation of regulators, relief valves, or
other equipment.
Condensate drain requirements
When the Water Heater is installed in a residential single family
dwelling without direct recirculation an external condensate
drain is not required.
If the Water Heater is installed in an application other than a
residential single family dwelling an external condensate drain
(not supplied with the Water Heater) is required in the following
circumstances:
• Vertical terminating exhaust vent installations.
• Horizontal terminating exhaust vent installations greater
than 6 feet (1.8 m) linear measurement, (NOT total
equivalent length).
• Vent installations where any section of the exhaust vent
pipe passes through an unconditioned space.
Note: An external condensate drain is recommended in all
installations as best practice inorder to maximize the longevity
of the Water Heater.
Diam. Approved terminals
E
x
h
a
u
s
t
3 or 4
inches
“T” terminal
90° elbow
PVCFlue Cap*(ECAP321)Verticalterminations
only 3" diameter only
Concentric (196016)
I
n
t
a
k
e
3 or 4
inches
“T” terminal
90° elbow
PVC Flue Cap*(ECAP321)Vertical & horizontal
terminations approved 3" diameter only
Concentric (196016)

Installation instructions
C 1210ES/ESC – 6 720 644 887 (2022/04)
18
Minimum combustion air and exhaust pipe length
The minimum exhaust pipe length is 1 foot (0.3m) of straight
vent pipe. The minimum combustion air pipe length is one 90°
elbow.
Maximum combustion air and exhaust pipe length
The following tables display the maximum allowable straight
pipe lengths for combustion air and exhaust piping with
consideration to the number of elbows used. Reduce the
equivalent length for each elbow used from the maximum
allowable length depending on the system used. Refer to
table 8 if using 3" diameter venting. Refer to table 9 if using 4"
diameter venting.
Table 8 Maximum Allowable Exhaust and Combustion Air
Lengths for 3" venting
Table 9 Maximum Allowable Exhaust and Combustion Air
Lengths for 4" venting
Use of elbows
It is recommended to limit the amount of elbows used in the
exhaust and combustion air piping to reduce friction in the air
flow. The following lists the maximum amount of 90° elbows
allowed in either the exhaust or combustion air piping:
Table 10
Two 45° elbows are equal to one 90° elbow. Any
combination of 45° and 90° elbows may be used in the vent
system as long as the combination does not exceed the
maximum listed in table 10 above.
Calculation example for 3" venting:
Exhaust
Table 11
Table 12
For this example, the maximum allowable exhaust pipe length is
12 feet.
Combustion air
Table 13
Table 14
3"
Venting
Maximum
allowable
Exhaust
pipe length
Combustion
air pipe
length
Elbow
Equivalency
90° 45°
Twin pipe
system
31ft 31ft 5 ft 3 ft
Concentric
system
23ft 23ft 5 ft 3 ft
4"
Venting
Maximum
allowable
Exhaustpipe
length
Combustion
air pipe
length
Elbow
Equivalency
90° 45°
Twin pipe
system
63ft 63ft 2.5ft 1.5ft
Concentri
c system
43ft 43ft 2.5ft 1.5ft
Max. number of 90° elbows 3" venting 4" venting
Twin pipe system 5 7
Concentric system 4 7
System used Concentric
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Calculation of example
Max. length 23’
90° elbow reduction - 5’
sub-total = 18’
45° elbow reduction - 6’
Total = 12’
System used Concentric
Number of 90° elbows needed: 2
Number of 45° elbows needed: 1
Calculation of example
Max. length 23’
90° elbow reduction - 10’
sub-total = 13’
45° elbow reduction - 3’
Total = 10’

Installation instructions
19
C 1210ES/ESC – 6 720 644 887 (2022/04)
For this example, the maximum allowable combustion air pipe
length is 10 feet.
Calculation example for 4" venting:
Exhaust
Table 15
Table 16
For this example, the maximum allowable exhaust pipe length is
58.5 feet.
Combustion air
Table 17
Table 18
For this example, the maximum allowable combustion air pipe
length is 55 feet.
System used Twin pipe
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Calculation of example
Max. length 63’
90° elbow reduction - 2.5’
sub-total = 61.5’
45° elbow reduction - 3’
Total = 58.5’
System used Twin pipe
Number of 90° elbows needed: 2
Number of 45° elbows needed: 2
Calculation of example
Max. length 63’
90° elbow reduction - 5’
sub-total = 58’
45° elbow reduction - 3’
Total = 55’

Installation instructions
C 1210ES/ESC – 6 720 644 887 (2022/04)
20
Required direct vent terminal clearances (twin pipe / concentric penetration)
Fig. 9
Canadian installations1)2) U.S. installations2)3)
AClearance above grade, veranda, porch, deck or
balcony
12 in. 12 in.
BClearance to window or door that may be opened 36 in. 12 in.
CClearance to permanently closed window * *
DVertical clearance to ventilated soffit located above the
vent termination within a horizontal distance of 2 feet
(61cm) from the center line of the termination
* *
EClearance to unventilated soffit * *
FClearance to outside corner * *
GClearance to inside corner * *
HClearance to each side of center line extended above
meter/regulator assembly
36 in. within a height 15 feet above
meter/ regulator assembly
*