Bosch 940ES User manual

940 ES
INDOOR MODEL
Temperature Modulated with Electronic Ignition
Suitable for heating potable water only and space heating
(Intended for variable flow applications)
940 ES - Natural Gas
940 ES - Liquefied Petroleum (LP) Gas
6 720 644 930 (2012/02) 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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2
Index
Index
1Warning 3
2 Appliance details 4
2.1 Features 4
2.2 Specifications (Technical data) 5
2.3 Unpacking the heater 6
2.4 General rules to follow for safe operation 7
2.5 Dimensions and Minimum
installation clearances 8
3 Installation instructions 9
3.1 Specialized tools 9
3.2 Introduction 9
3.3 Venting 9
3.4 Combustion air requirements 23
3.5 Proper location for installing your heater 24
3.6 Heater placement and clearances 24
3.7 Mounting installation 24
3.8 Mounting installation for manufactured
(mobile) homes 26
3.9 Gas piping & connections 26
3.10 Water connections 29
3.11 Water quality 29
3.12 Domestic hot water recirculation 30
3.13 Space heating applications 31
3.14 Measuring gas pressure 33
4 Electrical connections 34
4.1 Electrical power supply 34
4.2 Position of the fuses in control unit 34
5 Operation instructions 35
5.1 Description LCD display 35
5.2 For your safety read before operating
your water heater 36
5.3 Power 36
5.4 Temperature selection 36
5.5 Use of optional remote control accessory
(part no. TSTAT2) 37
5.6 Operation 37
5.7 Reset button 37
5.8 Program button 37
5.9 Locked condition 38
6 Maintenance and service 38
6.1 Annual maintenance 38
6.2 Winterizing for seasonal use 39
6.3 Mineral scale build-up 39
6.4 Adjusting CO2 40
6.5 Program values 42
6.6 Diagnostic menu 43
7 Troubleshooting 44
7.1 Introduction 44
7.2 Burner do not ignite when hot water
is turned ON 44
7.3 Water is too hot 44
7.4 Water is not hot enough 44
7.5 Low water flow/pressure 45
7.6 Hot water temperature fluctuates at tap 45
7.7 Noisy burner/heater during operation 45
8 Problem solving 46
8.1 Error code diagnostics 46
9 Electrical diagram 50
10 Sensor resistance charts 51
11 Functional scheme 52
12 Interior components diagram
and parts list 53
12.1 Interior components 53
12.2 Components diagram 55
13 Protecting the environment 61
14 LIFETIME LIMITED WARRANTY
FOR BOSCH TANKLESS
WATER HEATERS 62

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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 stainless steel vent
material suitable for category III vent
systems and temperatures up to 480°F.
Vent 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: Keep 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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Appliance details
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
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
• Real-time diagnostics for troubleshooting/
informational purposes
• LCD Display with backlight
• On/Off and Temperature control switches
• Reset button
• Program button (Selectable temperature default)
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 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.
Warning: Installation in mobile homes
shall conform to Title 24 CFR, Part
3280 and/or CAN/CSA Z240 MH Se-
ries, Mobile Homes.
HOT
BURN
DANGER
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.
6720608643-16.1AL

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Appliance details
5
• Failure codes for easy diagnostics and repair
• Easily removable one-piece cover
• 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 accessory to
operate with the appliance (TSTAT2)
• Cascading kit (77090003962)
• Outdoor kit (BTOK)
• External water filter (8703305356)
• Gas conversion kit (8719002176)
• Vertical vent kit (ESVVT)
• Concentric vent /air intake kit (ESHCK)
• Horizontal vent kit (4TWHVK3SII)1)
• Stainless steel bird screen (L2594)
(fits into a 3” PCV fitting - Intake vent).
• 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
160,500 Btu/h (47.0 kW)
Maximum input
199,000 Btu/h (58.3 kW)
Efficiency in %
Thermal efficiency > 82%
Min. 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 33.
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
• Design is NOx compliant with SCAQMD require-
ments - rule 1146,2 approved type 1 appliances.
•CO250 ppm (measured)
•CO
2level set from factory, see chapter 6.4, page 40.
1) 4TWHVK3S vent kit is compatible with this appliance
but requires the purchase of an additional 12" piece of
straight pipe to meet minimum vent length requirements.
The aluminum flex piping included with this kit is not
permissible for use with this appliance.
i
BOSCH is constantly improving its
products, therefore specifications are
subject to change without prior notice.