Bosch C 1210 ES/ESC User manual

Temperature Modulated with Electronic Ignition Suitable for heating potable water and space heating
(Intended for variable flow applications)
INDOOR RESIDENTIAL AND COMMERCIAL MODELS
C 1210 ES/ESC
Warning: If the information in this manual is not followed
exactly, a fire or explosion may result causing property dam-
age, personal injury or death.
Do not store or use gasoline or other flammable vapours and
liquids in the vicinity of this or any other appliance.
Improper installation, adjustment, alteration, service or main-
tenance can cause injury or property damage. Refer to this
manual. For assistance or additional information consult a
qualified installer, service agency or the gas supplier.
In the Commonwealth of Massachusetts this product must be
installed by a licensed plumber or gas fitter.
Upon completion ofthe installation, these instructions should
be handed to the user of the appliance for future reference.
What to do if you smell gas
• Close gas valve. Open windows.
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in
your building.
• Immediately call your gas supplier from a neighbour's
phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire depart-
ment.
• Installation and service must be performed by a qualified
installer, service agency or the gas supplier.
C 1210 ES/ESC - Natural Gas / C 1210 ES/ESC - Liquefied Petroleum (LP) Gas
6 720 644 887 (2013/02) US

2| Table of contents
C 1210 ES/ESC6 720 644 887 (2013/02)
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Appliance details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Specifications (Technical data) . . . . . . . . . . . . . . . . . . . . 7
3.3 Unpacking the heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.4 General rules to follow for safe operation . . . . . . . . . . . . 9
3.5 Dimensions and minimum installation clearances . . . 10
4 Installation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Specialized tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3 Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.4 Combustion air requirements . . . . . . . . . . . . . . . . . . . . 23
4.5 Proper location for installing your heater . . . . . . . . . . 23
4.6 Heater placement and clearances . . . . . . . . . . . . . . . . 23
4.7 Mounting installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.8 Gas piping & connections . . . . . . . . . . . . . . . . . . . . . . 24
4.9 Water connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.10 Water quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.11 Filling the condensate trap . . . . . . . . . . . . . . . . . . . . . . 28
4.12 Domestic hot water recirculation . . . . . . . . . . . . . . . . . 29
4.13 Space heating applications . . . . . . . . . . . . . . . . . . . . . . 29
4.14 Measuring gas pressure . . . . . . . . . . . . . . . . . . . . . . . . 31
5 Electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.1 Electrical power supply . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2 Position of the fuses in control unit . . . . . . . . . . . . . . . 32
6 Operation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1 Description LCD Display . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2 For your safety read before operating
your water heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.3 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.4 Temperature selection . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.5 Use of optional remote control accessory
(part no. TSTAT2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.7 Reset button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.8 Program button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.9 Locked condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7 Maintenance and service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1 Annual maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2 Winterizing for seasonal use . . . . . . . . . . . . . . . . . . . . . . 36
7.3 Mineral scale build-up . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.4 Condensing heat exchanger unit . . . . . . . . . . . . . . . . . . 36
7.5 Adjusting CO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.6 Program values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.7 Control board diagnostics . . . . . . . . . . . . . . . . . . . . . . . 39
8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8.2 Burner does not ignite when hot water is turned ON . . 40
8.3 Water is too hot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.4 Water is not hot enough . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.5 Low water flow/pressure . . . . . . . . . . . . . . . . . . . . . . . . 41
8.6 Hot water temperature fluctuates at tap . . . . . . . . . . . . 41
8.7 Noisy burner/heater during operation . . . . . . . . . . . . . . 42
9 Problem solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
9.1 Error code diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . 43
10 Electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
11 Sensor resistance charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
12 Functional scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
13 Interior components diagram and parts list . . . . . . . . . . . . . . 51
13.1 Interior components . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
13.2 Components diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
14 Protecting the environment . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
15 LIMITED WARRANTY FOR BOSCH THERM AND GREENTHERM
TANKLESS WATER HEATERS . . . . . . . . . . . . . . . . . . . . . . . . . . 61
15.1 Limited warranty for C 1210 ES residential model . . . 61
16 LIMITED WARRANTY FOR BOSCH THERM 1210 ESC TANKLESS
WATER HEATERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
16.1 Limited warranty for C 1210 ESC commercial model . 62
17 Installer Checklist to be completed by installer upon
installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Key to symbols and safety instructions | 3
6 720 644 887 (2013/02)C 1210 ES/ESC
1 Key to symbols and safety instructions
1.1 Key to symbols
Warnings
The following keywords are defined and can be used in this document:
•NOTICE indicates that damage to property may occur.
•CAUTION indicates that personal injury may occur.
•WARNING indicates that severe personal injury may occur.
•DANGER indicates that severe personal injury or death may occur.
Important information
Additional symbols
1.2 Safety instructions
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.
Installation and servicing
▶Risk of fire when soldering and brazing!
Take appropriate protective measures 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.
Installation and commissioning
▶ In the Commonwealth of Massachusetts, the water heater must be
installed by a licensed plumber.
▶ Do not install this device in rooms with a high moisture level
(e.g. bathrooms, saunas).
Function
▶ To ensure that the water heater functions properly, follow these
installation and maintenance instructions.
▶ Never close the blow-off line of the T&P safety valve. For safety
reasons, water may escape during heating.
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 the gas utility company and a trained
and certified installer.
If you smell flue gas
▶ Switch off the appliance.
▶ Open windows and doors.
▶ Inform a trained and certified installer.
Insufficient ventilation may cause toxic flue gas to escape. Risk of
poisoning.
▶ Never close off or reduce the sizeofthe air intake and outlet openings.
▶ The appliance must not be operated until any obstructions have been
removed.
▶ Inform the system operator in writing of the problem and the
associated dangers.
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.
Danger of explosion of flammable gases
▶ Work on gas components may only be carried out by a trained and
certified installer.
▶ Installation, gas and flue connection, initial commissioning, electrical
connections and annual maintenance must only be carried out by a
trained and certified installer.
Combustion air
▶ Keep the combustion air free of corrosive substances (halogenated
hydrocarbons that contain chlorine or fluorine compounds).
Never shut off safety valves!
▶ Water may escape from the safety valve at any time when the water is
being heated.
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! Damage caused by the use of parts not
supplied by Bosch may void the warranty.
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.
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.
Important information in cases where there is no risk of
personal injury or material losses is identified by the
symbol shown on the left. It is bordered by horizontal
lines above and below the text.
Symbol Explanation
▶ Step in an action sequence
Cross-reference to another part of the document
• List entry
– List entry (second level)
Table 1

4| Key to symbols and safety instructions
C 1210 ES/ESC6 720 644 887 (2013/02)
Danger from 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.
Risk of scalding at the hot water draw-off point
▶ When the water heater is 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, elderly, and handicapped persons are more likely to be
permanently injured by hot water. Never leave such individuals in the
tub or shower unattended under any circumstances. Children must
not be allowed to operate hot water faucets themselves or to fill a
bathtub.
▶ 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.
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 the ground
conductor (including metal fittings).
Maintenance
Customers are advised to:
▶ Sign a maintenance and inspection contract with an authorized
contractor. Inspect and maintain the water heater as necessary on a
yearly basis. Service as needed.
▶ Use only genuine spare parts.
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.

Key to symbols and safety instructions | 5
6 720 644 887 (2013/02)C 1210 ES/ESC
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.
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 12 (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.
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.

6| FCC rules
C 1210 ES/ESC6 720 644 887 (2013/02)
2 FCC rules
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.
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
• Key Pad interface control.
• High power pre-mix compact burner with low NOx emissions.
• Modulating Gas Valve with constant gas:air ratio control.
• Modulating water valve for improved comfort and 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.
• Reset button.
• 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 #)
• Optional wireless remote control to operate with the appliance
(TSTAT2)
• Cascading kit (7709003962)
• Outdoor kit (BTOK)
• External water filter (part # 8 703 305 356)
• Concentric termination kit (196016)
• Exhaust/Intake bird screen (L2594)
• Condensate drain tee (196061) [included with Concentric
termination kit]
• Pipe Cover (PTPCES)
• High temperature kit (7736500074)
• Recess box kit (7736500043)
• Pressure relief valve 150 PSI (7738001152)
Temperature Time to severe scalding1)
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.
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
Table 2 Approximate time-temperature relationship until there is a risk
of scalding
BOSCH is constantly improving its products, therefore
specifications are subject to change without prior
notice.

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3.2 Specifications (Technical data)
Approved in US/Canada
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
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 33
Dimensions
Depth inches (mm) 11 ¼ (286)
Width inches (mm) 17 7/8(452)
Table 3
Height inches (mm) 30½ (775)
Weight pounds (kg) 74 (33.5)
Gas types
Natural Gas
LP Gas
Voltage
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 page
31.
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.
If appliance is installed at elevations above 2000ft, refer
to chapter 4.3.7 Fan speed adjustment.
Technical characteristics Units C 1210 ES/ESC
Table 3

8| Appliance details
C 1210 ES/ESC6 720 644 887 (2013/02)
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
[A] Serial number
[B] 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.bosch-
climate.us)
• Product registration card
• Energy Guide label
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 21).
•Outdoor installation without installation of Outdoor kit (BTOK).
•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 | 9
6 720 644 887 (2013/02)C 1210 ES/ESC
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 11). 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 23).
•4. You must correctly vent your heater. See chapter 4.3 (page 11) 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 24).
•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

10 | Appliance details
C 1210 ES/ESC6 720 644 887 (2013/02)
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 | 11
6 720 644 887 (2013/02)C 1210 ES/ESC
Fig. 7 Side view
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:
▶ Damage or injury.
▶ Improper operation.
▶ Loss of warranty.
4.3 Venting
For servicing access, a 2ft clearance is recommended to
the front cover.
Model C 1210 ES/ESC
TOP (A) 12”
FRONT (B) 1”
BACK 0”
SIDES 1”
FLOOR (C) 12”
Table 4 Minimum clearances
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.
NOTICE:
▶ Do notreduce 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.
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.

12 | Installation instructions
C 1210 ES/ESC6 720 644 887 (2013/02)
4.3.1 Vent material
All combustion air and vent pipe materials and fittings must comply with
the following:
For specific questions concerning vent material, specifications,
usage or installation, please contact the vent manufacturer directly.
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).
The appliance can also be installed with separate air intake and exhaust
piping (see fig. 11, fig. 18 and fig. 19, page 19).
Fig. 8 Concentric vent kit example
[1] Exhaust
[2] Combustion air
[3] Roof boot/flashing (field supplied)
[4] Exhaust pipe
[5] Drain tee (196278)
[6] Intake pipe
[7] Concentric vent kit (196016)
[LA] Maintain 12 in. (18 in. for Canada) minimum clearance above
highest anticipated snow level maximum of 24 in. above roof
Item Material United States Canada
Vent or
air pipe
and
fitting
PVC schedule 40 ANSI/ASTM D1785 CSA or ULC
certified only
(ULC-S636)
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
Table 5 Approved vent material
Do not use cellular foam core pipe.
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
Table 6 Concentric vent part breakdown

Installation instructions | 13
6 720 644 887 (2013/02)C 1210 ES/ESC
4.3.2 Vent specifications
Establish vent clearances that comply with the vent manufacturer's
specifications and all applicable national/local codes.
Venting specifications
[*] ULC S636-95, UL1738 certified
Condensate drain requirements
An external condensate drain (not supplied with the heater) must be
installed under the following conditions:
• All vertical terminating vent installations.
• Horizontal terminating vent installations where the total linear vent
length is greater than 6 feet (1.8 m).
• Vent installations where any section of the exhaust vent pipe passes
through an unconditioned space.
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.
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:
Calculation example for 3" venting:
Exhaust
Combustion air
Diam. Approved terminals
E
x
h
a
u
s
t
3 or 4 inches “T” terminal
90° elbow
PVC Flue Cap*(ECAP321)Vertical terminations
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)
Table 7 Venting specifications for intake and exhaust
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
Table 8 Maximum Allowable Exhaust and Combustion Air Lengths for 3"
venting
4" Venting
Maximum
allowable
Exhaust pipe
length
Combustion air
pipe length
Elbow
Equivalency
90° 45°
Twin pipe
system
63ft 63ft 2.5ft 1.5ft
Concentric
system
43ft 43ft 2.5ft 1.5ft
Table 9 Maximum Allowable Exhaust and Combustion Air Lengths for 4"
venting
Max. number of 90° elbows 3" venting 4" venting
Twin pipe system 5 7
Concentric system 4 7
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.
System used Concentric
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Table 11
Calculation of example
Max. length 23’
90° elbow reduction - 5’
sub-total = 18’
45° elbow reduction - 6’
Total = 12’
Table 12
For this example, the maximum allowable exhaust pipe
length is 12 feet.
System used Concentric
Number of 90° elbows needed: 2
Number of 45° elbows needed: 1
Table 13
Calculation of example
Max. length 23’
90° elbow reduction - 10’
sub-total = 13’
45° elbow reduction - 3’
Total = 10’
Table 14
For this example, the maximum allowable combustion
air pipe length is 10 feet.

14 | Installation instructions
C 1210 ES/ESC6 720 644 887 (2013/02)
Calculation example for 4" venting:
Exhaust
Combustion air
System used Twin pipe
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Table 15
Calculation of example
Max. length 63’
90° elbow reduction - 2.5’
sub-total = 61.5’
45° elbow reduction - 3’
Total = 58.5’
Table 16
For this example, the maximum allowable exhaust pipe
length is 58.5 feet.
System used Twin pipe
Number of 90° elbows needed: 2
Number of 45° elbows needed: 2
Table 17
Calculation of example
Max. length 63’
90° elbow reduction - 5’
sub-total = 58’
45° elbow reduction - 3’
Total = 55’
Table 18
For this example, the maximum allowable combustion
air pipe length is 55 feet.

Installation instructions | 15
6 720 644 887 (2013/02)C 1210 ES/ESC
Required direct vent terminal clearances (twin pipe / concentric penetration)
Fig. 9
[*] For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA-B149.1, one of the following shall be indicated:
a) A minimum clearance value determined by testing in accordance with section 2.20, or;
b) A reference to the following footnote:
“Clearance in accordance with local installation codes and the requirements of the gas supplier.”
Canadian installations1) U.S. installations2)
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
*
IClearance to service regulator vent outlet 36 in. *
JClearance to non-mechanical air supply inlet to building or the
combustion air inlet to any other application
36 in. 12 in.
KClearance to mechanical air supply inlet 72 in. 36 in. above if within 10 feet
horizontally
LClearance above paved sidewalk or paved driveway located on
public property
84 in. 3) *
MClearance under veranda, porch deck or balcony 12 in. 4) *
Table 19
1) In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code.
2) In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code.
3) A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
4) Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor.

16 | Installation instructions
C 1210 ES/ESC6 720 644 887 (2013/02)
Required other than direct vent terminal clearances (single pipe penetration)
Fig. 10
[*] For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA-B149.1, one of the following shall be indicated:
a) A minimum clearance value determined by testing in accordance with section 2.20, or;
b) A reference to the following footnote:
“Clearance in accordance with local installation codes and the requirements of the gas supplier.”
Canadian installations1) U.S. installations2)
AClearance above grade, veranda, porch, deck or balcony 12 in. 12 in.
BClearance to window or door that may be opened 36 in. 4 feet below or to side of opening;
1 foot above opening
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
*
IClearance to service regulator vent outlet 36 in. *
JClearance to non-mechanical air supply inlet to building or the
combustion air inlet to any other application
36 in. 4 feet below or to side of opening;
1 foot above opening
KClearance to mechanical air supply inlet 72 in. 36 in. above if within 10 feet
horizontally
LClearance above paved sidewalk or paved driveway located on
public property
84 in. 3) 84 in.
MClearance under veranda, porch deck or balcony 12 in. 4) *
Table 20
1) In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code
2) In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code
3) A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
4) Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor.

Installation instructions | 17
6 720 644 887 (2013/02)C 1210 ES/ESC
4.3.3 Vent configuration examples
Below are approved examples of vertical and horizontal venting
installations.
Fig. 11 Vertical venting system (single pipe penetration)
[1] Drain tee
[2] Intake
[3] Exhaust
[LA] Maintain 12 in. (18 in. for Canada) minimum clearance above
highest anticipated snow level maximum of 24 in. above roof.
Fig. 12 Horizontal venting installation (combustion air piping not
shown)
[1] Termination
[2] Minimum above ground or normally expected snow accumulation
level
[3] Appliance
[4] Elbow (note: minimum 1ft of straight vent pipe required)
[5] Horizontal run ¼ " per foot down to termination
Fig. 13 Horizontal venting system (concentric vent)
[1] Exhaust
[2] Combustion air
[3] Exhaust pipe
[4] Drain tee
[5] Intake pipe
[LA] Minimum 1"
Fig. 14 Horizontal parallel venting system (twin pipe direct vent)
[A] 3 ft minimum
WARNING:
▶ Single pipe penetration should be used in non-
freezing climates only and steps must be taken to
ensure that adequate combustion air is available to
the water heater at all times!

18 | Installation instructions
C 1210 ES/ESC6 720 644 887 (2013/02)
Fig. 15 Horizontal venting system (single pipe penetration)
[1] Exhaust pipe
[2] Drain tee
[3] Intake pipe
[LA] Minimum 4"
4.3.4 Vent connections
Attaching the exhaust and air inlet connection adaptors to the top of
the heater
▶ Attach the flue gas exhaust accessory to the top of the unit fig. 16
(position 1) using the 4 screws and gasket provided, and fully insert
vent pipe into the accessory. If using 4" venting, a 3" to 4" increaser
should be installed directly after this accessory.
Fig. 16 Exhaust connection
▶ Attach the combustion air inlet accessory to the top of the unit fig. 17
(position 2) using the 3 screws and gasket provided, and install 3" air
intake pipe over the accessory.
Fig. 17 Inlet connection
4.3.5 Connecting the condensate water drain
Appliance condensate drain installation
The appliance comes equipped with an internal condensate drain and
siphon. This drains condensation formed in the secondary heat
exchanger. Piping must be installed under the condensate drain outlet
on the water heater and piped for disposal in accordance with local
codes.
WARNING:
▶ Single pipe penetration should be used in non-
freezing climates only and steps must be taken to
ensure that adequate combustion air is available to
the water heater at all times!
NOTE: Vent pipe must be completely vertical when
inserting or blue gasket inside exhaust accessory can
become displaced. Exhaust accessory can be removed
with vent pipe attached to check gasket position.
NOTE: The combustion air accessory can be installed on
the top right or on the top left side of the heater. The
combustion air inlet that is not used must be kept sealed.
WARNING:
▶ Failure to properly install condensate drain can
damage the appliance and will void the warranty.
WARNING:
▶ Do not install condensate drain tubing in areas where
it may freeze.
The condensate must be disposed of in accordance with
local codes.
See chapter 4.11 “Filling the condensate trap”.
Use materials approved by the authority having
jurisdiction. In the absence of other authority, PVC, and
CPVC pipe must comply with ASTM D1785, F441
orD2665. Cement and primer must comply with ASTM
D2564 or F493. For Canada, use CSA or ULC certified
PVC or CPVC pipe, fittings and cement, see table 5.

Installation instructions | 19
6 720 644 887 (2013/02)C 1210 ES/ESC
Fig. 18 Appliance drain installation
[1] Leave minimum ¼ " air gap
[2] Trap required
[3] 1 ½ " x ½ " PVC reducer
External condensate drain installation
If an external condensate drain (installer supplied) must be installed
(chapter 4.3.2), the following is recommended:
• 1. Install condensate drain on a horizontal section of the exhaust pipe
as close to the heater as possible.
• 2. The condensate must be disposed of according to local codes.
• 3. To install condensate drain in vent system, use PVC 3" X 3" X 1.5"
tee (part# 196278) and reduce for drain connection
Fig. 19 External condensate drain installation
[1] Condensate drain
[2] Dispose of condensate in accordance with local codes
[LA] Minimum 4"
4.3.6 Freeze prevention
In cold climates, components of a tankless water heater can freeze and
burst from negative draft. A leading cause of negative draft is
combustion appliances in the building not being supplied with sufficient
combustion air. A wood stove or furnace can pull its combustion air from
the water heater‘s vent pipe, allowing the cold incoming air to freeze the
cold water in the heat exchanger. Supplying more combustion air for all
combustion appliances is the solution. A HVAC specialist should be
consulted to design solutions for providing more combustion air.
Listed below is an additional measure designed to further limit backdraft
in extreme conditions assuming all other possible causes have been
addressed.
Backdraft reducer
The Heat Fab backdraft reducer (9301BFP) is the preferred option for
limiting backdraft (see fig. 20).
Note: The following solution is available only for 3" diameter
venting.
Fig. 20 Part nr 9301BFP
Installation
For this solution to be effective, the internal flapper must be 100%
closed when the water heater is not running. Refer to Figures 22 and23
for preferred installation positions in the vent system.
Installation considerations:
• Install damper per the supplied manufacturer‘s instructions.
• The damper is only to be used in the exhaust vent piping.
• Ensure directional arrow on damper label faces in the same direction
as exhaust flow.
• If installed horizontally, the axis must be horizontal or slightly pitched
up towards termination to ensure damper closes 100% when heater
is not running.
• To allow accessibility, damper must not be installed in an enclosed
section of vent pipe.
• Do not install damper in unconditioned spaces (e.g. attics)
Condensation can build up while the heater is running which can later
freeze and potentially block the flapper.
Fig. 21 Blackflow reducer (9301BFP) installed
6720608643-18.1V
6720608643-19.1V

20 | Installation instructions
C 1210 ES/ESC6 720 644 887 (2013/02)
Fig. 22
[1] Good
[2] Better
[3] Best
Fig. 23
[1] Good
[2] Better
[3] Best
[4] Enclosed vent pipe (Do not install damper)
[5] Unconditioned space (Do not install damper)
[6] Preferred damper position for vertical terminations