Bosch OptiFlow Professional GWH12 1 CTD E23 User manual

Installation Manual
Gas continuous flow water heaters
OptiFlow Professional
6720808877-00.1V
GWH12 1 CTD E23/31 F3 OL
6 720 810 559 (2016/06) AU
Read installation manual prior to installation of this appliance!
Read user manual before putting this unit in operation!
Observe the warnings in the manuals!
The installation location must meet the requirements for sufficient ventilation!
Installation by an authorised person only!

6 720 810 559 (2016/06) OptiFlow Professional
2 | Index
Index
1 Key to symbols andsafety instructions . . . . . . . . . . 3
1.1 Key to symbols . . . . . . . . . .. . . . . . . . . . . . . 3
1.2 General safety instructions . . . . . . . . . . . . . . 3
2 Product details . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . 5
2.1 Declaration of Conformity . . . . . . . . . . . . . . 5
2.2 Type overview . . . . . . . . . . .. . . . . . . . . . . . . 5
2.3 Included items . . . . . . . . . . .. . . . . . . . . . . . . 5
2.4 Rating plate . . . . . . . . . . . . .. . . . . . . . . . . . . 5
2.5 Description of appliance . . . . . . . . . . . . . . . . 5
2.6 Accessory .. . . . . . . . . . . . . . . .. . . . . . . . . . 5
2.7 Dimensions and minimum clearances . . . . . 6
2.8 Appliance layout . . . . . . . . .. . . . . . . . . . . . . 7
2.9 Electrical wiring diagram . . . . . . . . . . .. . . . 8
2.10 Specification . . . . . . . . . . . . . . . . . .. . . . . . . 9
3 Regulations . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . 10
4 Installation (only by authorised technicians) . . . . 10
4.1 Choice of installation site . .. . . . . . . . . . . . 11
4.1.1 Regulations concerning the
installation site . . . . . . . . . .. . . . . . . . . . . . 11
4.2 Minimum clearances . . . . . . . . . . . .. . . . . . 11
4.3 Installing the appliance .. . . . . . . . . . . . . . . 12
4.4 Water connection . . . . . . . . . . .. . . . . . . . . 12
4.4.1 Temperature mixing device
(not supplied with the appliance) . . . . . . . 12
4.5 Gas connection . . . . . . .. . . . . . . . . . . .. . . 12
4.6 Altitude of installation site region . . . . . . . . 12
4.7 Remote control connection (optional) . . . . 13
5 Electrical connection
(only by authorised technicians) . . . . . . . . . . . . . . 13
5.1 Connecting the power cable . . . . . . . . . . . . 13
5.2 Commissioning of the appliance . . . . . . . . 14
6 Regulating the gas
(only for authorised technicians) . . . . . . . . . . .. . . 14
6.1 Factory regulation . . . . .. . . . . . . . . . . .. . . 14
6.2 Service function . . . . . . . . . . . . . . . . . . . . . 14
6.3 Adjusting the appliance . . . . . . . . .. . . . . . 15
6.3.1 Access to the pressure heads . . . . . . . . . . . 15
6.3.2 Adjusting the maximum flow
(Parameter P1) . . . . . . . . . . . . .. . . . . . . . . 15
6.3.3 Adjusting the minimum flow
(Parameter P2) . . . . . . . . . . . .. . . . . . . . . .15
6.3.4 Adjusting pressure in the burner
(Parameter P0) . . . . . . . . . . . .. . . . . . . . . .16
6.4 Factory default settings . . . . . . . . . . . . . . . 16
7Maintenance
(only by authorised technicians) . . . . . . . . . . . . . . .17
7.1 Periodic maintenance works . . . . . . . . . . . 17
7.2 Replacement of the fuse
(electronic control unit) . . . . . . . . . . . . . . . .17
7.3 Start-up after completion of maintenance 17
8 Troubleshooting . . . . . . . . . . .. . . . . . . . . . . . .. . . . . 18
9 Environment / disposal . . . . .. . . . . . . . . . . . .. . . . . 20
10 Water quality . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . 21
11 Warranty details . . . . . . . . . .. . . . . . . . . . . . . . . .. . 22

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Key to symbols and safety instructions | 3
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:
•NOTICEindicatesasituationthatcouldresultindamageto
property or equipment.
•CAUTIONindicatesa situationthat could result in minorto
medium injury.
•WARNING indicates a situation that could result in severe
injury or death.
•DANGER indicates a situation that willresult in severe
injury or death.
Important information
Additional symbols
1.2 General safety instructions
If you notice dark combustion gases or sooting:
▶ Isolate the Gas supplyto the heater.
▶ Notify an authorised technician.
Installation, assembly, and modifications
Installation, assembly, and modifications to the heater must
only be performed by an authorised technician.
Maintenance
▶ The water heater is required to have a service and safety
inspection every two years.
▶ The installer is responsible for the safety and
environmental compatibility of the installation, according
to local regulations.
▶ TheOwner/Userisresponsibleforkeepingtheareaaround
the water heater free from debris.
▶ Safe access to inspect and service the water heater is the
responsibility of the property owner.
▶ Use only genuine Bosch spare parts.
Explosive and highly flammable material
▶ Donotstore oruseflammable material(paper,spraycans,
solvents, paints, etc) near the heater.
Combustion air and surroundingair
▶ The combustion air and surrounding air must be free from
corrosive substances.
▶ Do not spray aerosols or use chemicals around the heater
unless heater is disconnected from the power supply.
Risk of damage due to operator error
User error can result in injury and damage to property.
▶ Ensure that children never play with or operate this
appliance.
▶ Ensure thatonly personnel who can operate this appliance
correctly have access to it.
▶ Refer to the operating and user instructions before
adjusting the water heater.
To be installed and serviced only by an authorised person
The “authorised installing person” is responsible for:
• Correct installation and commissioning of this appliance.
• Ensuring the appliance performs to the specifications
stated on the rating label.
• Demonstrating the operation of the appliance to the
customer before leaving.
• Handing these instructions to customer.
THIS APPLIANCE IS NOT SUITABLE FOR POOL OR SPA POOL
APPLICATIONS.
NOT SUITABLE FOR COMMERCIAL BOOSTING OF A WARM
WATER RECIRCULATION SYSTEM"
Regulations
All local by-laws and regulations pertaining to installation and
use of gas appliances must be observed.
This appliance must be installed in accordance with the
manufacturers installation instructions, AS/NZS5601, AS/
NZS3500, and all Local Building & Gas fitting regulations.
Warningsinthisdocumentareidentifiedbya
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.
This symbol indicates important information
where there is no risk to people or property.
Symbol Explanation
▶ Step in an action sequence
Cross-reference to another part of the document
•Listentry
– List entry (second level)
Table 1

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4 | Key to symbols and safety instructions
This appliance must not be installed indoors or in an enclosed
space.Thisapplianceisapproved foroutdoorinstallationonly.
Donot installthisappliancewithany modificationoralteration.
Failure to install this appliance in accordance with these
installation instructions will void the warranty and may create
an unsafe situation.
Installation
Important information
▶ Determine most suitable location for the appliance. Install
only on an external wall as close as possible to the most
frequently used hot water outlet.
▶ Ensurethemountingstructureiscapableofsupportingthe
weightoftheapplianceonceinstalled.Securetheheaterto
the wall using fixings suitable for the weight of the
appliance and the wall material.
▶ Installgas andwaterisolationvalvesascloseaspossibleto
the heater. Only use gate valve orfull flow ball valve (fixed
mechanism type) for cold water.
▶ Check the cold water supplypressure to ensure it meets
the required supply pressure for the appliance. (see
table 5).
▶ Ifinlet water pressureexceeds 800 kPa a pressurelimiting
valve(500kPa)MUSTbefitted.Thepreferablelocationfor
the pressure limiting valve is at the water meter.
▶ Wherethepressurelimitingvalveislessthan3metresfrom
the hot water unit, it must be fitted in conjunction with a
cold water expansion valve (700 kPa), between the water
heater and the pressure limiting valve.
▶ Failure to comply with this requirement may void the
warranty.
▶ Refer to AS/NZS5601 for the relevant gas pipe sizing.
▶ After finishing the gas pipingsystem, the pipes must be
thoroughly purged and leak tested. This test must be
performed with the gas isolation valve of the appliance
closed.
▶ Ensurethegas pressure andflowthroughthe regulator are
appropriate for the consumption of the heater (see table
5). Refer to As/NZS5601 and AS3500.1 for the relevant
pipe size.
Note: Incorrect pipe sizing or gas supply pressure may cause
theappliancetounderperform.Servicecalls forincorrectpipe
sizing and/or gas pressure, will NOT be covered under
warranty.
Safetyof electricalappliancesfordomesticuseandsimilar
purposes
The following requirements apply in accordance with EN
60335-1 in order to prevent hazards from occurring when
using electrical appliances:
DANGER:
This appliance must not be installed indoors
or in an enclosed space in accordance with
AS/NZS5601.
DANGER: Explosion Risk!
▶ Always turn offthe gas valve before
carrying out any work on components
which carry gas.
DANGER: Appliance malfunction!
This appliance must be installed with no
obstructions to air entry openings.
▶ Periodiccheckingofopeningstoensure
no blockage or obstruction of the air
openings from plants, debris or insects
must be carried out.
The installation ofgas, water, and electrical
supply, and the initial startup are to be
performed by an authorised person.
Notsuitable for poolorspapoolapplications.
Not suitable for commercial boosting of
warm water recirculation systems.
Installation in marine environments can lead
toprematurecorrosion.Prematurecorrosion
duetotheinstallationenvironmentwouldnot
be covered by warranty.
Allgasappliancesrequireadequateairintake
to ensure correct combustion. Insects and
dirt ingress may affect combustion causing
sooting. If you notice sooting from the flue
outlet the unit would require servicing. Pest
and dirt ingress is not covered by the
manufacturers warranty.

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Product details | 5
“Thisappliancecanbeusedbychildrenof8yearsandolder,as
well as by people with reduced physical, sensory or mental
capabilities orlacking in experience andknowledge,if theyare
supervised and have been given instruction in the safe use of
the appliance and understand the resulting dangers. Children
must not play with the appliance. Cleaning and user
maintenance must not be performed by children without
supervision.”
“If the power cable is damaged, it must be replaced by the
manufacturer, its customer service department or a similarly
qualified person, so that risks are avoided.”
2 Product details
2.1 Declaration of Conformity
The appliance has been AS 4552 tested.
2.2 Type overview
[GWH]Gas continuous flow water heater
[12] Capacity (l/min)
[1] Generation
[CT] Thermostatic
[D] Digital user interface
[E] Electric ignition
[23] Appliance set for natural gas
[31] Appliance set for Universal LP gas
[F3] Open flue with fan
[O] Outdoor installation
[L] Locked water temperature adjustment
2.3 Included items
• Gas continuous flow water heater
• Fixing brackets
• Appliance documentation
2.4 Rating plate
The rating plate is located on the outside of the appliance, on
the bottom.
The particular room has the indications on the performance of
the appliance, approval data and the serial number.
2.5 Description of appliance
• Wall-mounted appliance
• Remote control with multifunctional display panel
(optional)
• Appliance for operating with natural gas or Universal LPG
• Electronic ignition
•Waterflowsensor
•Watervalve
• Temperaturesensorsformonitoringthetemperatureofthe
incoming and outgoing water of the appliance.
•Safetydevices:
–Flamesensorrod
–Thermalfuse
– Outgoing water temperature sensor
– Electronic control unit
–Airtemperaturesensor
– Frost-protection
• Electrical connection: 230 V, 50 Hz
2.6 Accessory
• Remote control
Model GWH12 1 CTD E23/31 F3 OL...
Table 2
GWH 12 1CTDE23 F3 OL
GWH 12 1CTDE31 F3 OL
Table 3

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6 | Product details
2.7 Dimensions and minimum clearances
Fig. 1 Dimensions (in mm)
B
C
240
A
583
6720808877-02.1V
>10 >10
107120 80
51
Connections
Water Gas
A B C Cold Hot Nat. LPG
GWH12 300 570 170 ½“ ½“ ½“ ½“
Table 4 Dimensions (in mm)

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Product details | 7
2.8 Appliance layout
Fig. 2
[1] Flue terminal
[2] Flame sensor rod
[3] Burner
[4] Air pressure test point
[5] Fan
[6] Air temperature sensor of the box
[7] Thermal fuse
[8] Hot water temperature sensor
[9] Hot water outlet
[10] Connecting lead with plug
[11] Remote control (optional)
[12] Ignition electrode
[13] Gas pressure test point
[14] Water flow sensor and Water valve
[15] Electronic control box
[16] Cold water temperature sensor
[17] Gas valve
[18] Cold water valve
[19] Incoming gas pressure test point
[20] Gas inlet
[21] Frost protection
6720808877-03.1V
10
2
3
4
5
8
9
6
7
11
15
13
14
20
18
19
17
16
21
12
1

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8 | Product details
2.9 Electrical wiring diagram
Fig. 3 Electrical diagram
[1] Flame sensor rod
[2] Fan
[3] Ignition electrode
[4] Power supply
[5] Connection for frost-protection device
[6] Connection for remote control (optional)
[7] Modulation electrovalve (gas)
[8] Segmentation electrovalve 1 (gas
[9] Segmentation electrovalve 2 (gas)
[10] Safety electrovalve (gas)
[11] Thermal fuse
[12] Water flow sensor
[13] Air temperature sensor
[14] Hot water temperature sensor
[15] Cold water temperature sensor
[16] Water valve

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Product details | 9
2.10 Specification
Technical features Units GWH12
Performance
Nominal gas consumption MJ/h 90.0
Minimum gas consumption MJ/h 11.9
Efficiency at 100% of nominal load % 82.4
Gas supply data
Gas supply pressure (flowing)
Natural gas (when operating) kPa 1.13
Universal LP gas (when operating) kPa 2.75
Water supply data
Maximum permissible pressure (static) kPa 1000
Minimum operating pressure kPa 100
Minimum water flow l/min 2.2
Maximum flow, corresponding to a temperature increase of 25 °C l/min 12.0
Maximum inlet temperature °C 80
Electrical circuit
Power supply voltage V 230
Frequency Hz 50
Maximum power consumption W 228
Appliance enclosure rating IPX5D
General data
Weight (unpacked) kg 10
Height mm 570
Width mm 300
Depth mm 170
Table 5

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10 | Regulations
3Regulations
Any local by-lawsand regulations pertaining to installation and
use of gas-fired appliances must be observed.
This appliance must be installed in accordance with the
manufacturers installation instructions, AS/NZS5601 and all
Local Building & Gas fitting regulations
It is recommended that sanitary fixtures used for the purpose
ofpersonal hygienehavea temperaturelimitingdevice suchas
a tempering valve be fitted as per AS3498.
This appliance must not be installed indoors or in an enclosed
space as per AS/NZS5601.
4 Installation (only by authorised
technicians)
Thermal solar system (thermosiphon)
Fig. 4 Thermal solar system
[1] Incoming water
[2] Pre heated water line
[3] Thermostatic valve
[4] Expansion tank or valve
[5] Pressure relief valve
[6] Hot water line
DANGER:
Thisappliancemustnotbeinstalledindoors.
DANGER: Explosion!
▶ Always shut off the gas valve before
carrying out work on gas pipes.
The appliance installation, electrical
connection, gas connection, and the initial
start-up are operations to be carried out by
authorised technicians only.
CAUTION:
▶ The temperature of the incoming water
of the appliance must not exceed 80 °C.
▶ If the incoming watertemperature
exceeds 80 °C, fit a 3-way or
thermostatic valve adjusted to less than
80 °C (solar transfer valve).
▶ In the case of a thermal solar system,
ensure that the installation has an
expansion vessel or valve.
Installation in marine environments can lead
to premature corrosion. Premature
corrosionduetotheinstallationenvironment
would not be covered by warranty.
Not suitable for pool or spa pool
applications.
WARNING: Scalding!
This appliance can deliver water exceeding
50 °C.
▶ Please refer to AS/NZS 3500.4 local
requirements and installation
instructions for additional temperature
control requirements.
6
2
1
3
6720817545-08.1V
T
5
4

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Installation (only by authorised technicians) | 11
4.1 Choice of installation site
4.1.1 Regulations concerning the installation site
▶ Installtheapplianceoutdoors.Thetopoftheunitshouldbe
positioned at less than 1800mm from the ground (the
bottom should remain at more than 300mm).
▶ The water heater may not be installed over a heat source.
▶ Complywiththeminimuminstallationclearancesindicated
in Fig. 5 and Table 6.
▶ Ensure that there is an external weatherproof powerpoint
in the area and that it is easily accessible after the
installation of the water heater.
Location of the appliance
The air intake of this applianceis located on the rear of the
housing.
▶ Ensure this intake is free from vegetation and other
obstructions.
In order to prevent corrosion, the combustion air must not
contain any corrosive substances.
Substances classed as corrosion-promoting include
halogenated hydrocarbons which containing chlorine and
fluorine compounds. They may be found in solvents, paints,
adhesives, aerosol propellants and household cleaners.
If these conditions cannot be guaranteed, a different site must
be chosen for the appliance.
Surface temperature
The maximum surface temperature of the appliance is below
85 °C. No special safety precautions are required with regard
to flammable building materials and fitted furniture.
▶ Ensure that local building codes and regulations are
followed.
4.2 Minimum clearances
• Install the appliance in accordance with the minimum
installation clearances indicated in Fig. 5 and Table 6,
according to AS/NZS5601
• The appliance must not be installed over a heat source.
• Do not obstruct the openings of appliance.
• The appliance must installed in a position that is easily
accessible to allow service work. It is recommended the
appliance is installed no more than 2m from the ground to
the base of the appliance.
• The areas 30cms above and below the appliance must be
clear of obstacles.
Fig. 5 Minimumflueclearances(useasaguideonly,always
AS/NZS5601 ).
Ventilation requirements as per
AS/NZS5601.
Item Min.clea-
rance (mm)
A Below eaves, balconies and other
projections 300
B From the ground, above a balcony or other
surface1) 300
C From a return wall or external corner1) 300
D From a gas meter (GM) 1000
E From an electricity meter or fuse box (P)2) 500
F From a drain pipe or soil pipe 75
G Horizontally from any building structure 1)
or obstruction facing a terminal 500
H From any other flue terminal, cowl, or
combustion air intake1) 300
J Horizontally from an openable window, door, non-
mechanical air inlet, or any other opening into a building
with the exception of sub-floor ventilation:
Appliances up to 150 MJ/h input1) 300
Appliances over 150 MJ/h input up to 200
MJ/h input1) 300
K From a mechanical air inlet, including a spa
blower 1000
N Vertically below an openable window, non-mechanical air
inlet, or any other opening into a building with the
exception of sub-floor ventilation:
Appliances over 50 MJ/h input and up to
150 MJ/h input 1000
Table 6
6720817545-09.2V
N
CJ
B
J
A
C
A
K
G
A
H
N
F
J
A
C
K
BB
B
G
K
H
Flue terminal positions
for water heaters in accordance
with AS/NZ5601
D
DGM
P
K
EE

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12 | Installation (only by authorised technicians)
4.3 Installing the appliance
▶ Remove the appliance from the packaging.
▶ Check that all the material indicated is included.
▶ Remove the covers from the gas and water connections.
▶ Check that the gas type available matches that shown on
the sticker on the front of appliance, and on its dataplate.
4.4 Water connection
▶ Identifythecold and hot waterpipeto avoidpossiblecross
connection.
▶ Install a pressure reducing valve if required. It's preferable
to install this valve close to the water meter.
▶ Completethecold(Fig. 2.[18])andhot(Fig. 2,[9])water
connections.
4.4.1 Temperature mixing device (not supplied with the
appliance)
It is recommended that for sanitary fixtures use primarily for
the purpose of personal hygiene,that a temperature control
device be fitted (such as a tempering valve) as per AS3498.
4.5 Gas connection
The gas connection to the water heater mustabsolutely with
AS/NZS5601.
▶ First ensure that the water heater corresponds to the gas
type available.
▶ Fit a gas shut-off valve on the gas supply line as close as
possible to the appliance.
▶ After installation of the gas supply line, thorough purging
and a tightness test must be carried out.
4.6 Altitude of installation site region
To ensure correct operation of the appliance, it must be
indicated the region altitude of the installation site.
▶ Enter the Service function (section 6.2).
Display with “P2”.
▶ Press until the display shows “P4”.
▶ Press the button .
Display with indication “E”.
▶ Press until the display shows “AS”.
▶ Press the button .
Display with indication “1”.
▶ Press the button or to select the region altitude
of the installation site according to below table.
▶ Press the button for 3 seconds.
Appliances over 150 MJ/h input 1500
1) unless appliance is certified for closer installation
2) Prohibitedareabelowelectricitymeterorfuseboxextends
to ground level
NOTICE: The appliance may be damaged if
dirt is allowed to enter via the gas or water
connections.
▶ Purge the pipes to eliminate
possible foreign bodies.
CAUTION:
▶ Never support or balance the water
heater on the water and gas
connections.
Packaging materials can be recycled.
WARNING:
This water heater can heat water to
temperatures which cause scalding.
Item Min.clea-
rance (mm)
Table 6
DANGER:
Non-compliance with applicable legal
standards may cause a fire or explosion,
causing material damage or personal injury
or even death.
Size gas supply as per AS/NZ5601.
Incorrect gas pipe sizing will not be covered
by the warranty.
Display Altitude
1 < 500 m
2 500 m - 1 000 m
3 1 000 m - 1 500 m
4 1 500 m - 2 000 m
5 2 000 m - 2 500 m
6 > 2500 m
Table 7

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Electrical connection (only by authorised technicians) | 13
4.7 Remote control connection (optional)
Connectingthe communicationcableto theremote control
▶ Open the remote control.
▶ Remove the larger connector from the communication
cable.
▶ Connect the larger connector to the controller in the
position shown in Fig. 7.
▶ Remove the plastic tag to allow the cable to be feed
through.
▶ Feed the end of the cable without a connector through the
opening in the back cover.
▶ Reconnect the cable to the larger connector.
▶ Refit the frontand back covers back together.
▶ Close the remote control.
Fig. 6
[1] Remote control front cover
[2] Remote control back cover
[3] Communication cable
Connecting the communication cable to the appliance
▶ Connect the communication cable to the appliance.
Fig. 7
The remote control connection is concluded.
5 Electricalconnection(onlybyauthorised
technicians)
All the regulating, control and safety devices in the appliance
are factory supplied already connected and ready to operate.
5.1 Connecting the power cable
2
1
1.
6720806426-03.1V
3
DANGER: Due to electric shock!
▶ Before carrying out work on electrical
components, disconnect the power
supply (230 V AC) (fuse, circuit
breaker) and secure against
unintentional reconnection.
CAUTION: Electrical storm!
▶ The appliance must have an
independent connection in the electric
box, protected by a differential safety
switchof30mAandgroundline.Inareas
with frequent electrical storms, a
protector against electrical storms must
also be fitted.
The electrical connection must be done in
accordance with AS/NZS3000.
1.
6720808877-04.1V

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14 | Regulating the gas (only for authorised technicians)
▶ Connect the power cable to a power socket.
5.2 Commissioning of the appliance
▶ Open the gas and water isolation valves and check the
tightness of all the connections.
If a controller is connected:
▶ place the ON/OFF button in the operating position.
The appliance is now ready to operate.
When a hot water tap is turned on, the passage of water
through the flow sensor (Fig. 2, [14]) sends a signal to the
control box. This signal triggers the following actions:
• The fan to start working.
• The ignition sequence and the gas valve (Fig. 2, [13])
delivers gas to the burner.
• Theburnerignites.Initiallyonlyonesectionoftheburneris
lit, with remain sections igniting depending on the heat
required.
•Theflamesensorrod(Fig.2,[2]) detects the presence of
the flame.
• The temperature of the water is automatically adjusted by
the fan, gas and water valves.
Safety shut-down when the safety time is exceeded
If it is notpossible to obtain theflame within the safety interval
stipulated, a safety shut-down is carried out.
Thepresenceofairin the gassupplypipe(initialstart-upofthe
applianceorstart-upafterlongperiodsofinactivity)maycause
a delay or difficulty when igniting.
Iftheignitionattemptisunsuccessfulafteraperiodoftime,the
safetydevices block the operationoftheappliance, andair will
have to be purged from the circuit.
Safety shut-down due to an excessively high water
temperature
The electronic control unit detects the temperature of the
water through the thermistor placed at the hot water outlet. If
the appliance detects an excessive temperature, a safety
shutoff will occur.
Safety shut-off due to incorrect flue conditions
If the appliance detects an incorrect flue condition, a safety
shut-off will occur
Re-start after a safety shut-down
To put the appliance back into operation after asafety shut-off:
▶ Close all hot water taps.
▶ Reset the appliance by switching it off at the socket and
unplugging the cord.
6 Regulating the gas (only for authorised
technicians)
6.1 Factory regulation
The data plate on the each appliance will show the factory
setting of that appliance.
Natural gas
Universal LPG
6.2 Service function
Accessing the service function
▶ Pressandholddownatthesametime , and
for 3 seconds.
Fig. 8 Service function
Display with indication "P2".
The service function is activated.
If the power cable is damaged, it must be
replaced with a Bosch supplied spare part.
The appliance must not beoperated if the
dynamic connection pressure is less than
1.13 kPa or greater than 2.75 kPa.
The appliance must not beoperated if the
dynamic connection pressure is:
Universal LPG: less than 2.5 kPa or greater
than 4.5 kPa.
DANGER:
▶ Theoperationsdescribedbelow must only
be carried out byan authorised technician.
6720806426-02.1V

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Regulating the gas (only for authorised technicians) | 15
6.3 Adjusting the appliance
6.3.1 Access to the pressure heads
▶ Remove the front of the appliance.
Fig. 9
[A] Air pressure test point
[B] Gas pressure test point
6.3.2 Adjusting the maximum flow (Parameter P1)
▶ Connect the appliance on the ON/OFF button.
▶ Loosen the test point screw of the gas pressure test point
.[B]
▶ Connect the pressure gauge connection "+" to the gas
pressure test point.
▶ Loosen the test point screw of the air pressure test point
[A].
▶ Connect the negative (-) side of the pressure gauge to the
air pressuretest point [A].
▶ Press until the display shows "P1".
▶ Press the button .
Display with indication "E".
▶ Press until the display shows "L1".
▶ Press the button .
The appliance is in the position for adjustment of the
maximum gas flow.
▶ Open a hot water tap.
▶ Press or until the pressure gauge shows the
value indicated in tab. 8.
▶ Press for 3 seconds.
The value flashes as a sign of confirmation.
▶Press .
Display will show "L1".
▶ Close the hot water tap.
▶ Press until the display shows"E".
▶ Press the button .
Display will show P1.
The adjustment of the maximum gas flow is completed.
6.3.3 Adjusting the minimum flow (Parameter P2)
▶ Press until the display shows"P2".
▶ Press the button .
Display will show "E".
▶ Press until the displayshows "L2".
▶ Press the button .
▶ Open a hot water tap.
Theapplianceis nowready foradjustmentof theminimum
gas flow.
▶ Press or until the pressure gauge shows the
value indicated in tab. 8.
▶ Press for 3 seconds.
The displayed value flashes as a sign of confirmation.
▶Press .
Display will show "L2".
▶ Close the hot water tap.
▶ Press until the display shows"E".
▶ Press the button .
Display will show "P2".
▶ Simultaneously press the , and for 3
seconds.
Display with indication of temperature selected.
▶ Disconnectthepressuregaugefromthetestpoints[A]and
[B].
▶ Tighten the shutter screws of the pressure test points [A]
and [B].
The adjustment of the minimum gas flow is complete.
If it is not possible to reach the differential
pressure value:
▶ Adjust the pressure in the burner
(section 5.3.4) and repeat the
procedure for adjusting minimum flow.
A
B
-+
6720804089-11.1V
If it is not possible to reach the differential
pressure value:
▶ Adjust the pressure in the burner
(section 6.3.4) and repeat the
procedure for adjusting minimum flow.

6 720 810 559 (2016/06) OptiFlow Professional
16 | Regulating the gas (only for authorised technicians)
6.3.4 Adjusting pressure in the burner (Parameter P0)
▶ Enter the service mode by pressing and holding down the
, , and buttons simultaneously for 3
seconds (section 6.2).
Display will show "P2".
▶ Press until the display shows "P0".
▶ Press the button .
▶ Open a hot water tap.
Withthepressuregaugeconnected,letthevaluemeasured
stabilise.
▶ Press or until the pressure gauge shows the
value indicated in tab. 8.
▶ Press for 3 seconds.
The displayed value flashes as a sign of confirmation
▶ Press to exit this function.
Display will show P0.
▶ Close the hot water tap.
The adjustment of the burner pressure is complete.
6.4 Factory default settings
▶ Enter the service mode by pressing and holding down the
, , and buttons simultaneously for 3
seconds (section 6.2).
Display will show"P2".
▶ Press until the display shows "P4".
▶ Press the button .
Display will show“E”.
▶ Press until the display shows "rP".
▶ Press the button .
Display will show "P1"
▶ Press for 3 seconds.
The value flashes as a sign of confirmation.
▶ Press .
Display will show "P1"
▶ Press until the display shows "P2".
▶ Press the button for 3 seconds.
The value flashes as a sign of confirmation.
▶ Press .
Factory default settings are now restored.
Natural gas H Universal
LP gas
Øinjector GWH12 1.7 1.3
Dynamic
connection
pressure
(mbar)
GWH12 11.3 27.5
Burner
pressure
(mbar) - P0 GWH12 1,2
Differential
pressure of
the burner
MAX (mbar) -
P1
GWH12 4.6 - 5.0 6.3 - 6.7
Differential
pressure of
the burner
MIN (mbar) -
P2
GWH12 0.5 - 0.8 0.5 - 0.8
Table 8 Pressure of the burner
Burner pressures adjustment isonly
requiredif“L1”and“L2”cannotbeachieved
according to table, 8.

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Maintenance (only by authorised technicians) | 17
7 Maintenance (only by authorised
technicians)
Bosch recommend that to maintain optimum performance
fromthisappliance, servicingshouldbe carried out bysuitably
licensed persons at intervals not greater than two (2) years.
▶ Your appliance should only be attended to by a Bosch
servicetechnician.Tolocateyournearestserviceprovider,
call: AU 1300 30 70 37, NZ 0800 54 33 52
▶ Only use Bosch supplied replacement parts.
7.1 Periodic maintenance works
Functional check
▶ Checktheproperoperationofallthesafety,regulationand
verification elements.
Heat exchanger
▶ If heat exchanger is showing signs of sooting:
– Remove the heat exchanger.
– Clean by applying a jet of water in the lengthwise
direction of the fins.
▶ Ifthesootisnotremoved,useastiffbrushtocarefullyclean
the fins.
▶ Regions with average/high water hardness: descale the
inside of the heat exchanger and the connection pipes by
using a diluted solution of hydrochloric acid or white
vinegar.
▶ When reinstalling the heat exchanger replace the o-rings
and seals.
Burner
▶ Inspect the burner and clean it if necessary.
If cleaning is required:
▶ Dismantle the burner.
▶ Use a brush to clean the surface of the burner elements.
▶ Use a jet of air to blow the burner elements clean.
Water filter
▶ Close the cold water inlet isolation valve.
▶ Unscrew the water filter on the cold water pipe.
▶ Carefully remove the water filter.
▶ Replace the water filter.
7.2 Replacement of the fuse (electroniccontrol
unit)
▶ Loosen the fixing screw of the electronic control unit.
▶ Release all the connections to the control box.
▶ Open the electronic control unit.
▶ Replace the fuse.
7.3 Start-up after completion of maintenance
▶ Re-tighten all of the connections.
▶ Check the burner pressure.
▶ Check tightness of the flue circuit with the front cover
fitted.
▶ Check that there are no gas or water leaks.
Maintenance must only be performed by an
authorised service technician.
DANGER: Due to electric shock!
▶ Always isolate the electrical power to
the appliance (by turning offthe power
pointandremovingthe powerplugfrom
the electrical socket) before carrying
out any work on electrical parts.
NOTICE: Damage to the appliance.
Damage to the heat exchanger.
▶ Do not apply a jet that is too strong or
aimed in a direction other than that
indicated.

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18 | Troubleshooting
8Troubleshooting
Fitting, maintenance and repair must only be carried out by authorised technicians. The following table describes the possible
solutions.
Display Description Solution
A0 Cold and hot temperature sensor damaged. ▶ Check temperature sensor and associated
connections.
▶ Ifthe problem persists, call an authorised
service technician.
A1 Temperature inside the water heater housing is high
(heat exchanger calcified or sooted). ▶Theapplianceautomatically regulates its performance to avoid overheating.
▶ Ifthe problem persists, call an authorised
service technician.
A4 Faulty air temperature sensor. ▶ Call an authorised service technician.
A7 Faulty hot water outlet temperature sensor. ▶ Check temperature sensor and associated
connections.
▶ Ifthe problem persists, call an authorised
service technician.
A9 Hot water temperature sensor is not fitted properly.
Incoming gas pressure low.
▶Checkfitting.
▶Checkincomingpressure.
C7 Faulty fan. ▶ Check if the fan is properlyconnected to
ECU.
▶ Ifthe problem persists, call an authorised
service technician.
CA Water flow above maximum specified value. ▶ Check incoming water pressure.
▶ Install a pressure limiting valve if necessary.
CF
C1
Blocked flue gas outlet.
Air flow sufficient forstart-up.
▶ Remove dirt or any other impediment in the
flue and air inlet.
▶ Close and open a hot water tap.
▶ Ifthe problem persists, call an authorised
service technician.
E0 Failure of control module. ▶ Unplug the electrical connection for 10
seconds.
▶ Reconnect and restart the appliance.
▶ Ifthe problem persists, call an authorised
service technician.
E1 Hot water temperature sensor detects overheating. ▶ Let the appliance cool and try again.
▶ Ifthe problem persists, call an authorised
service technician.
Table 9

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Troubleshooting | 19
Note:Note:breakdownsdiagnosedbythewaterheaterthroughanindicationintheLCDpanelresultin the blocking of the appliance
for safety reasons. Once the problem is solved, you can reset the appliance by pressing theon/off button or byunplugging and
replugging the power supply cord. To locate your nearest service agent, call: AU 1300 30 70 37, NZ 0800 54 33 52.
E2 Cold temperature sensor faulty. ▶ Check temperature sensor and associated
connections.
▶ If the problem persists, call an authorised
service technician.
E4 Air temperature sensor detects overheating (leaking
combustion products inside the combustion
chamber).
▶ Switchoffatthepowerpointandremovethe
plug from the electrical socket.
▶ Do not try to restart the appliance.
E9 Activated thermal fuse. ▶ Call an authorised service technician.
EA Flame not detected. ▶ Check that the gas to the appliance has not
been turned off.
▶ Unplug the electrical connection for 10
seconds.
▶ Reconnect and restart the appliance.
▶ If the problem persists, call an authorised
service technician.
EC Failure ionization during operation ▶ Check type of gas.
▶ Check gas pressure.
▶ Check the ignition system.
▶ Check the output of combustion gases and
remove dirt or other impediment to good
extraction.
EF Wrong gas connected. ▶ Call an authorised service technician.
F7 A flame is detected although the appliance is
switched off. ▶ Unplug the electrical connection for 10 seconds.
▶ Reconnect and restart the appliance.
▶ If the problem persists, call an authorised
service technician.
FA Fault in the gas control valve. ▶ Call an authorised service technician.
FC Buttonsstuckin a'pressed'positionformorethan30
seconds. ▶ Release the button.
▶ If the problem persists, call an authorised
service technician.
With indication,
butwithoutexistenceof
solar thermal system.
The temperature selected is lower than the minimum
power that the appliance supplies.
High incoming water temperatures, or low flow rate
can create this occurrence.
▶ Increase the hot water flow.
-or-
▶ Select a higher temperature.
▶ If the problem persists:
▶ Call an authorised service technician.
With indication
and water temperature
low.
Appliance is making resonance noise (vibration). ▶ Call an authorised service technician.
Display Description Solution
Table 9

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20 | Environment / disposal
9 Environment / disposal
Environmental protection is a fundamental corporate strategy
of the Bosch Group.
Thequalityofour products,theirefficiencyandenvironmental
safety are all of equal importance to us and all environmental
protection legislation and regulations are strictly observed.
We use the best possible technology and materials for
protecting the environment taking into account of economic
considerations.
Packaging
We participate in the recycling programmes of the countries in
which our products are sold to ensure optimum recycling.
All of ourpackaging materials areenvironmentallyfriendlyand
can be recycled.
Used appliances
Used appliances contain valuable materials that should be
recycled.
Thevariousassembliescanbeeasilydismantledandsynthetic
materialsaremarkedaccordingly.Assembliescanthereforebe
sorted by composition and passed on for recycling or disposal.