Bosch C950ES User manual

C 950 ES
INDOOR MODEL
Temperature Modulated with Electronic Ignition
Suitable for heating potable water and space heating
(Intended for variable flow applications)
C 950 ES - Natural Gas
C 950 ES - Liquefied Petroleum (LP) Gas
6 720 646 812 (2011/05) US
Warning: If the information in this manual is not
followed exactly, a fire or explosion may result
causing property damage, personal injury or death.
Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any other
appliance.
Improper installation, adjustment, alteration,
service or maintenance 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 of the 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 neighbor’s
phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire
department.
• Installation and service must be performed by a
qualified installer, service agency or the gas supplier.

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Index
Index
1 Warning 3
2 Appliance details 5
2.1 Features 5
2.2 Specifications (Technical data) 5
2.3 Unpacking the heater 6
2.4 General rules to follow for safe operation 8
2.5 Dimensions and minimum
installation clearances 9
3 Installation instructions 10
3.1 Specialized tools 10
3.2 Introduction 10
3.3 Venting 10
3.4 Combustion air requirements 24
3.5 Proper location for installing your heater 25
3.6 Heater placement and clearances 25
3.7 Mounting installation 25
3.8 Gas piping & connections 26
3.9 Water connections 29
3.10 Water quality 29
3.11 Filling the condensate trap 31
3.12 Domestic hot water recirculation 32
3.13 Space heating applications 33
3.14 Measuring gas pressure 35
4 Electrical connections 36
4.1 Electrical power supply 36
4.2 Position of the fuses in control unit 36
5 Operation instructions 37
5.1 Description LCD Display 37
5.2 For your safety read before operating
your water heater 38
5.3 Power 38
5.4 Temperature selection 38
5.5 Use of optional remote control accessory
(part no. TSTAT2) 39
5.6 Operation 39
5.7 Reset button 39
5.8 Program button 40
5.9 Locked condition 40
6 Maintenance and service 41
6.1 Annual maintenance 41
6.2 Winterizing for seasonal use 41
6.3 Mineral scale build-up 42
6.4 Condensing heat exchanger unit 42
6.5 Adjusting CO2 43
6.6 Program values 45
6.7 Control board diagnostics 46
7 Troubleshooting 47
7.1 Introduction 47
7.2 Burner does not ignite when hot
water is turned ON 47
7.3 Water is too hot 47
7.4 Water is not hot enough 47
7.5 Low water flow/pressure 48
7.6 Hot water temperature fluctuates at tap 48
7.7 Noisy burner/heater during operation 48
8 Problem solving 49
8.1 Error code diagnostics 49
9 Electrical diagram 53
10 Sensor resistance charts 54
11 Functional scheme 56
12 Interior components diagram
and parts list 57
12.1 Interior components 57
12.2 Components diagram 59
13 Protecting the environment 66
14 LIFETIME LIMITED WARRANTY
FOR BOSCH PRO TANKLESS
WATER HEATERS 67
15 Notes 69

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Warning
3
1 Warning
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.
Warning: 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.
Warning: Exhaust gas must be vented
to outside using approved vent material
See table 2, page 10 (For Canada use
only ULCS636 approved material).
Vent and combustion air connector
piping must be sealed gas-tight to
prevent possibility of flue gas spillage,
carbon monoxide emissions and risk of
fire, resulting in severe personal injury
or death. Approved vent terminators
must be used when penetrating to the
outside.
Warning: Place the heater in a location
where water leaks will do NO DAMAGE
to adjacent areas or lower floors.
Warning: 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.
Warning: 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: 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 psig.
Warning: 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.
Warning: 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: Keeping appliance area clear
and free from combustible materials,
gasoline and other flammable vapors
and liquids.
Warning: Do not obstruct the flow of
combustion and ventilation air.
Warning: Precautions must be taken
prior to manually operating the relief
valve to avoid contact with hot water
coming out of the relief valve and to
prevent water damage.
Caution: Label all wires prior to
disconnection when servicing controls.
Wiring errors can result in improper and
dangerous operation.
Verify proper operation after servicing.

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Warning
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 opera-
tion.
Fig. 1
Warning: 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: 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: Toxic chemicals, such such
as those used for boiler treatment, shall
not be introduced into the potable water
used for space heating.
Warning: 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.
HOT
BURN
D A N G E R
Water temperature over 125°F can
cause severe burns instantly or
death from scalds.
Children, disabled and elderly are
at highest risk of being scalded.
See instruction manual before
setting temperature at water
heater.
Feel water before bathing or
showering.
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Appliance details
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2 Appliance details
2.1 Features
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
• On/Off and Temperature control switches
• Reset button
• Program button (Selectable temperature default)
• Failure codes for easy diagnostics and repair
• Real-time diagnostics for troubleshooting/informa-
tional 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 out-
side the appliance from freezing. Precautions should be
taken.
Accessories (Bosch part #)
• Optional wireless remote control to operate with the
appliance (TSTAT2)
• Cascading kit (77090003962)
• 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 Con-
centric termination kit]
• Pipe Cover (PTPCES)
• High temperature kit (7736500074)
• Recess box kit (7736500043)
• Pressure relief valve (FWL-2).
2.2 Specifications (Technical data)
Approved in US/Canada
Capacity
Maximum flow rate: 7.15 GPM (27 l/min) at a 45°F
(25°C) rise.
Maximum output
157,700 Btu/h (46.2 kW)
Maximum input
175,000 Btu/h (51.2 kW)
Efficiency in %
Thermal efficiency > 92%
Minimum Input
19,900 Btu/h (5.8 kW)
Temperature Control
Selection range: 100°F (38°C) - 140°F (60°C)
Default temperature: 122°F (50°C)
Stability: +/- 2°F (+/- 1°C)
Gas Requirement
Gas connection (inches) - ¾”
Inlet gas pressure under operation (with a high hot
water flow rate)*
• Propane: 8” - 13” water column
• Natural Gas: 3.5” - 10.5” water column.
* To measure Gas Pressure, see Measuring Gas
Pressure, chapter 3.14, page 35.
Water
• Hot water connection (inches) - ¾”
• Cold water connection (inches) - ¾”
• Water valve material: Polymer (PPS) (Polypropylene
Sulfid)
• Minimum water flow: 0.5 gallon/minute (1.9 l/m)
Note: Activation varies with inlet water temperatures
from 0.5 - 1.6 gallon/minute (1.9 - 6.1 l/m).
• Minimum recommended water pressure: 30 PSI
(2.07 bar)
• Minimum well pressure 40 psi, see page 29.
• Connections:
– Bottom of heater
Combustion
• NOx ≤14 Ng/J
(Nanograms of NOx (calculated as NO2) per
Joule of heat output).
i
BOSCH is constantly improving its
products, therefore specifications are
subject to change without prior notice.

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Appliance details
• CO ≤290 ppm (measured)
• CO
2
level set from factory, see chapter 6.5, page 43.
Dimensions
• Depth (in): 11¼” (286 mm)
• Width (in): 17
7
/
8
” (452 mm)
• Height (in): 30½” (775 mm)
• Weight: 74 pounds (33.5 kg).
Gas types
Natural Gas.
LP Gas.
Voltage
120 V AC (60 Hz) nominal
Amperage
Idle - 40 mA
Operation - ≤2.5 A
Noise
45 - 65 db (A)
Safety devices
• Flame failure device (ionization flame rod sensor)
• Overheat prevention (temperature limiter)
• Inlet temperature sensor
• Outlet temperature sensor
• Back flow temperature sensor
• Exhaust gas temperature sensor.
Water protection
IP X4 (protection against water drops)
2.3 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
ASerial number
BType of gas
The box includes:
• C 950 ES
• Bracket for wall hanging the heater
• Exhaust vent adaptor (with 4 screws and gasket
provided)
• Combustion air inlet adaptor (with 3 screws and gas-
ket 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 950 ES 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.
i
If appliance is installed at elevations above
2000ft, refer to Section 3.3.7 Fan speed
adjustment.

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Appliance details
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To remove front cover
BLoosen the two Phillips head screws located on
bottom rear of cover (see Fig. 3).
Fig. 3 Loosen the two screws
BLift front cover panel upward and remove.
Fig. 4 Remove the front cover
To remove combustion cover (service only)
BOpen the four clips and remove the combustion
cover (see Fig. 5).
Fig. 5 Remove the combustion cover
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Appliance details
2.4 General rules to follow for safe
operation
B1. 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.
B2. 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.
B3. 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 3.3 (page 10). 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 3.4 (page 24).
B4. You must correctly vent your heater. See
chapter 3.3 (page 10) on VENTING.
B5. 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).
B6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate
the heater over any material which might burn.
B7. 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 3.8 (page 26).
B8. 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.
B9. 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.
B10. Failure to install heater correctly may lead to
unsafe operation and void the warranty.

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Appliance details
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2.5 Dimensions and minimum installation clearances
Fig. 6 Dimensions
1On/Off button
2Reset button
3Program key
4Power ON or stand-by LED
5LCD display
6Up button
7Down button
Fig. 7 Minimum clearances
Note: For servicing access, a 2ft clearance is
recommended to the front cover.
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4
Model C 950 ES
TOP (A) 12”
FRONT (B) 1”
BACK 0”
SIDES 1”
FLOOR (C) 12”
Table 1 Minimum clearances

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Installation instructions
3 Installation instructions
3.1 Specialized tools
The following specialized tools may be required for
installation:
• Manometer
• Multi-meter
• Combustion Gas Analyzer.
3.2 Introduction
Please follow these instructions. Failure to follow
instructions may result in:
BDamage or injury.
BImproper operation.
BLoss of warranty.
3.3 Venting
3.3.1 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 (see section 3.3.4) 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 18).
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.
i
Common installation practice is to
first determine the venting/
combustion air point of termination,
then design the piping layout back to
the heater.
Warning:
BDo not reduce the exhaust or
combustion air vent pipe sizes.
BDo not common vent with any other
vented appliance or stove.
BDo 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 2 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 terminator.
¼" mesh minimum opening
recommended on screen.
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 40 ANSI/ASTM D2661
Pipe
cement /
primer
PVC ANSI/ASTM D2564
CPVC ANSI/ASTM F493
ABS ANSI/ASTM D2235
Table 2 Approved vent material
i
Do not use cellular foam core pipe.