Bosch OptiFlow Professional GWH16 1 CTD E23 F5 L User manual

Installation Manual
Room sealed gas continuous flow water heaters
Optiflow Professional
6720808879-00.1V
GWH12 | 16 | 20 1 CTD E23/31 F5 L
6 720 810 560 (2017/11) AU

2
Index
Optiflow Professional – 6 720 810 560 (2017/11)
Index
1 Key to symbols and safety instructions . . . . . . . . . . 3
1.1 Key to symbols . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Safety Information . . . . . . . . . . . . . . . . . . . . . 3
2 Product details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Declaration of Conformity . . . . . . . . . . . . . . 7
2.2 Type overview . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Included Items . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Rating plate . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Description of appliance . . . . . . . . . . . . . . . . 7
2.6 Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.7 Dimensions and minimum clearances . . . . . 8
2.8 Appliance layout . . . . . . . . . . . . . . . . . . . . . . 9
2.9 Electrical wiring diagram . . . . . . . . . . . . . . 10
2.10 Specification . . . . . . . . . . . . . . . . . . . . . . . . 11
2.11 Flue accessories . . . . . . . . . . . . . . . . . . . . . 12
2.11.1 Selecting the Right Flue . . . . . . . . . . . . . . . 12
2.11.2 Vertical installation . . . . . . . . . . . . . . . . . . . 14
2.11.3 Horizontal installation . . . . . . . . . . . . . . . . . 14
3 Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4 Installation (only by an authorised technicians) . 14
4.1 Important information . . . . . . . . . . . . . . . . . 14
4.2 Choice of installation site . . . . . . . . . . . . . . 15
4.2.1 Regulations concerning the installation
site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2.2 Overall flue length of the installation . . . . . 15
4.3 Minimum clearances . . . . . . . . . . . . . . . . . . 15
4.4 Fitting hanging-plate . . . . . . . . . . . . . . . . . . 16
4.5 Installing the appliance . . . . . . . . . . . . . . . . 16
4.6 Water connection . . . . . . . . . . . . . . . . . . . . 16
4.7 Gas connection . . . . . . . . . . . . . . . . . . . . . . 16
4.8 Installation of flue accessories . . . . . . . . . . 16
4.9 Altitude of installation site . . . . . . . . . . . . . 17
4.10 Electrical connection (only by authorised
technicians) . . . . . . . . . . . . . . . . . . . . . . . . 18
4.10.1 Connecting the power cable . . . . . . . . . . . . 18
4.11 Commissioning of the appliance . . . . . . . . 18
4.12 Changing the setpoint limit temperature (only
for 55 °C preset appliances) . . . . . . . . . . . 18
4.13 Delivery temperature calibration . . . . . . . . 18
5 Regulating the gas
(only for authorised technicians) . . . . . . . . . . . . . . .19
5.1 Factory settings . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Service function . . . . . . . . . . . . . . . . . . . . . 19
5.3 Adjusting the appliance . . . . . . . . . . . . . . . 19
5.3.1 Access to the test points . . . . . . . . . . . . . . . 19
5.3.2 Adjusting the maximum flow
(Parameter P1) . . . . . . . . . . . . . . . . . . . . . .19
5.3.3 Adjusting the minimum flow
(Parameter P2) . . . . . . . . . . . . . . . . . . . . . .20
5.3.4 Adjusting pressure at the burner
(Parameter P0) . . . . . . . . . . . . . . . . . . . . . .20
5.4 Factory default settings . . . . . . . . . . . . . . . 21
6Maintenance
(only by authorised service technician) . . . . . . . . .21
6.1 To remove the front panel . . . . . . . . . . . . . 21
6.2 Periodic maintenance . . . . . . . . . . . . . . . . . 21
6.3 Replacement of the fuse (electronic control
unit) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
6.4 Start-up after completion of maintenance 22
6.5 Safe operation/ risk for prolonged use . . . 22
7 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8 Environmental considerations . . . . . . . . . . . . . . . . 25
9 Water quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
10 Warranty details . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

3
Key to symbols and safety instructions
Optiflow Professional – 6 720 810 560 (2017/11)
1 Key to symbols and safety instructions
1.1 Key to symbols
Warnings
The following keywords are defined and used in this document:
•NOTICE indicates a situation that could resultin damage to
property or equipment.
•CAUTION indicates a situation that could result in minor to
medium injury.
•WARNING indicates a situation that could result in severe
injury or death.
•DANGER indicates a situation that will result in severe
injury or death.
Important information
Additional symbols
1.2 Safety Information
If you smell gas
A gas leak could potentially cause an
explosion. If you smell gas, observe the
following rules.
▶ Avoid producing flames or sparks:
– Do not smoke, do not use a lighter
or strike matches.
– Do not operate any electrical
switches or unplug any equipment.
– Do not use the telephone or ring
doorbells.
▶ Turn off the gas supply at the main
shut-off valve or at the gas meter.
▶ Open windows and doors.
▶ Warn your neighbours and leave the
building.
▶ Prevent anyone from entering the
building.
▶ Stay well away from the building: call
the emergency services and the gas
supplier.
If you notice dark combustion gases
or sooting:
▶ Isolate the gas supply to the heater.
▶ Notify an authorised technician.
Installation, Assembly and
Modifications
Installation,assembly andmodifications
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.
▶ The Owner/User is responsible for
keeping the area around the water
heater free from debris.
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.
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

4
Key to symbols and safety instructions
Optiflow Professional – 6 720 810 560 (2017/11)
▶ 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
▶ Do not use or store flammable
materials in or near this appliance.
Combustion air and surrounding air
▶ The combustion air and surrounding
air must be free from corrosive
substances.
▶ Do not spray aerosols in the vicinity of
this appliance while it is in operation.
Risk of damage due to user error
User errors can result in injury and
damage to property.
▶ Ensure that children never play with
or operate this appliance.
▶ Ensure that only personnel who can
operate this appliance correctly have
access to it.
▶ Refer to the operating and user
instructions before adjusting the
water heater.
Tobeinstalled andservicedonly byan
authorised person
The authorised installer 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 the operating instructions to
the 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.
The appliance must not be installed
outdoors. The appliance is approved for
indoor installation only. Do not modify
this appliance.
Failure to install this appliance in
accordance with these installation
instructions will void the warranty and
may create an unsafe situation.

5
Key to symbols and safety instructions
Optiflow Professional – 6 720 810 560 (2017/11)
Installation
Important information
▶ Determine the most appropriate
location for the appliance. Install as
close as possible to the most
frequently used hot water outlet.
▶ Ensure the mounting structure is
capable of supporting the weight of
the appliance once installed. Secure
the heater to the wall using fixings
suitable for the weight of the
appliance and the wall material.
▶ Do not place articles on or against this
appliance.
▶ Install gas and water isolation valves
as close as possible to the appliance.
Only use a gate valve or full flow ball
valve (fixed mechanism type) for cold
water.
▶ Check the cold water supply pressure
to ensure it meets the required supply
pressure for the appliance. (see
table 5, page 11).
▶ If inlet water pressure exceeds 800
kPa a pressure limiting valve (500
DANGER: Explosion Risk!
▶ Always turn off the gas
valve before carrying out
any work on components
which carry gas.
DANGER: Appliance
malfunction!
This appliance must be
installed with no
obstructions to the flue
terminal.
▶ Periodic checking of the
flue terminal to ensure no
blockage or obstruction
of the openings from
plants, debris or insects
must be carried out.
The installation of gas,
water, and electrical supply,
and the initial startup are to
be performed by an
authorised person.
Not suitable for pool or spa
pool applications.
Not suitable for commercial
boosting of warm water
recirculation systems.
All gas appliances require
adequateair intaketoensure
correct combustion. Insects
and dirt ingress may affect
combustion causing sooting.
Ifyou notice sooting from the
flue outlet the unit would
require servicing. Pest and
dirt ingress is not covered by
the manufacturers warranty.

6
Key to symbols and safety instructions
Optiflow Professional – 6 720 810 560 (2017/11)
kPa) MUST be fitted. The preferable
location for the pressure limiting
valve is at the water meter.
▶ Where the pressure limiting valve is
less than 3 metres from 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.
▶ Referto AS/NZS5601 for the relevant
gas pipe sizing.
▶ After finishing the gas piping system,
the pipes must be thoroughly purged
and leak tested. This test must be
performedwith the gas isolationvalve
of the appliance closed.
▶ Ensure the gas pressure and flow
through the regulator are appropriate
for the consumption of the heater
(see table 5, page 11). Refer to AS/
NZS5601 and AS3500, for the
relevant pipe size.
Note: Incorrect pipe sizing or gas supply
pressure may cause the appliance to
under perform. Service calls for
incorrect pipe sizing and/or gas
pressure, will NOT be covered under
warranty.
Safety of electrical appliances for
domestic use and similar purposes
The following requirements apply in
accordancewith EN 60335-1 inorder to
prevent hazards from occurring when
using electrical appliances:
“This appliance can be used by children
of 8 years and older, as well as by people
with reduced physical, sensory or
mental capabilities or lacking in
experience and knowledge, if they are
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.”

7
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
2 Product details
2.1 Declaration of Conformity
The appliance has been tested and certified to Australia
Standards.
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
[F5] Tight chamber
[L] Locked water temperature adjustment
2.3 Included Items
• Gas continuous flow water heater
• Fixing bracket
• Appliance documentation
2.4 Rating plate
The rating plate is located on the outside of the appliance, on
the bottom.
The rating plate has the indications on the performance of the
appliance, approval data and the serial number.
2.5 Description of appliance
• Room sealed wall-mounted appliance for internal
installation
• Multifunctional display panel
• Suitable for Natural Gas or Universal LPG
• Electronic ignition
• Water flow sensor
•Watervalve
• Temperature sensors for monitoring the temperature of the
incoming and outgoing water of the appliance.
•Safetydevices:
–Flamesensorrod
–Thermalfuse
– Hot water temperature sensor
– Electronic control unit
–Airtemperaturesensor
– Frost protection device
• Electrical connection: 230 V, 50 Hz
2.6 Accessory
• Flue accessories
• Mains remote control (optional).
• Bathroom remote control (optional).
Model GWH12/16/20 1 CTD E23/31 F5 L...
Table 2
GWH 12 1 CT D E 23 F5 L
GWH 12 1CT D E 31 F5 L
GWH 16 1 CT D E 23 F5 L
GWH 16 1CT D E 31 F5 L
GWH 20 1 CT D E 23 F5 L
GWH 20 1CT D E 31 F5 L
Table 3

8
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
2.7 Dimensions and minimum clearances
Fig. 1 Dimensions (in mm)
Connections
Water Gas
A B C D E Cold Hot Nat. Universal
LPG
GWH12 300 570 170 120 107 ½ “ ½ “ ½ “ ½ “
GWH16 364 570 175 142 137
GWH20 364 570 175 142 137
Table 4 Dimensions (in mm)

9
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
2.8 Appliance layout
Fig. 2
[1] Heat exchanger
[2] Flame sensor rod
[3] Burner
[4] Air pressure test point
[5] Fan
[6] Air temperature sensor
[7] Thermal fuse
[8] Hot water temperature sensor
[9] Hot water outlet
[10] Power cord and plug
[11] Combustion gas collector
[12] Frost protection device
[13] Ignition electrode
[14] Burner pressure test point
[15] Water flow sensor and Water valve
[16] Electronic control unit
[17] Cold water temperature sensor
[18] Gas shut-off valve
[19] Cold water inlet
[20] Gas pressure test point
[21] Gas inlet

10
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
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
[6] Connection for remote control
[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

11
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
2.10 Specification
Technical features Units GWH12 GWH16 GWH20
Performance
Nominal Gas Consumption MJ/h 90.0 120.2 149.0
Minimum gas consumption MJ/h 11.9 18.0 18.0
Efficiency at 100% of nominal load %82.4 82.4 82.4
Gas supply data
Gas supply pressure (flowing)
Natural gas (when operating) kPa 1.13 1.13 1.13
Universal LP gas (when operating) kPa 2.75 2.75 2.75
Water supply data
Maximum permissible pressure (static) kPa 1000 1000 1000
Minimum operating pressure kPa 100 100 100
Start-up flow l/min 2.0 2.0 2.0
Maximum flow, corresponding to a temperature increase of 25 °C l/min 12.0 16.0 20.0
Maximum inlet temperature °C 50 50 50
Electrical circuit
Power supply voltage VAC 230 230 230
Frequency Hz 50 50 50
Maximum power consumption W228 228 228
Appliance enclosure rating IPX4D
General data
Weight (unpacked) kg 10 11 12
Height mm 570 570 570
Width mm 300 364 364
Depth mm 170 175 175
Table 5

12
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
2.11 Flue accessories
2.11.1 Selecting the Right Flue
▶ Map your flue configuration.
▶ Check that the configuration, including bends, is within the
maximum flue limits.
▶ Calculate whether a condensate trap is required using
Fig. 4.
▶ Choose the flue kit that best suits your application. The kit
includes the appliance adapter and terminal.
▶ Add any flue lengths, bends, or condensate traps required
for your configuration.
▶ Place your order using the Bosch part numbers shown
below.
Bosch 4000S coaxial flue must be used with
this appliance. Failure to use Bosch 4000S
flue could result in appliance failure.
DANGER: Install the flue gas pipe so that
there are no leaks.
▶ Non compliance with this requirement
may cause combustion gases to leak
through the appliance installation
compartment and may result in personal
injury or death.
Below is a list of accessories. Only use
original accessories.
Type Description Reference
AZ369 Vertical Flue Kit (Fixed 1.4m) 7 716 050 071
AZ361 Telescopic Horizontal Flue Kit 500-725mm 7 716 050 063
AZ362 Horizontal Flue Kit (Fixed 0.8m) 7 716 050 064
--- Horizontal Flue Kit w/ Adaptor Ø 60/100 7 736 995 083
Table 6 Flue gas accessories Ø60/100 mm

13
Product details
Optiflow Professional – 6 720 810 560 (2017/11)
Flue condensate collector
We advise using a condensate trap when the flue length and the
lowest average inlet air temperature is likely to result in
condensate forming during operation.
When the intersection of the flue length and lowest average
inlet air temperature is in the white section of the graph, a
condensate trap is required. (See Fig. 4)
Fig. 4
[A] Flue pipe length
[B] Lowest average inlet air temperature
--- Flue Elbow Ø 60/100 90° 7 736 995 079
--- Flue Elbow Ø 60/100 45° 7 736 995 071
--- Flue Terminal Extension DN60/100 350mm 7 736 995 059
--- Flue Terminal Extension DN60/100 750 mm 7 736 995 063
--- Flue Terminal Extension DN60/100 1500 mm 7 736 995 067
--- Horizontal Condensate Trap Ø 60/100 7 736 995 087
--- Vertical Flue Condensate Trap Ø 60/100 7 736 995 089
Type Description Reference
Table 6 Flue gas accessories Ø60/100 mm
Add note on using 100m 2 pce clips.
(A)
10 m
9 m
7 m
6 m
8 m
5 m
4 m
3 m
2 m
1 m
0 m
0°C-5°C-10°C 5°C 10°C 15°C 20°C 25°C
(B) 6720809968-04.3V

14
Regulations
Optiflow Professional – 6 720 810 560 (2017/11)
Bosch 4000S flue components
All 4000S coaxial flue components have an internal pipe
diameter of 60 mm and an external pipe diameter of 100 mm.
2.11.2 Vertical installation
Maximum lengths (Lmax)
2.11.3 Horizontal installation
Maximum lengths (Lmax)
3Regulations
Any local by-laws and 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
of personal hygiene have a temperature limiting device such as
a tempering valve be fitted as per AS3498.
4 Installation (only by an authorised
technicians)
4.1 Important information
▶ Before carrying out the installation, consult the gas supply
company and the standard on gas appliances and
ventilation of rooms.
▶ Install in accordance with AS/NZS5601, AS/NZS3500.4,
NZS5261 and all local building, water and gas fitting
regulations.
Lmax
Concentric pipes
GWH12
GWH16
12 m
GWH20 10 m
Table 7
Lmax
Concentric pipes
GWH12 8 m
GWH16
GWH20 6 m
Table 8
In case of horizontal flue, ensure that the
installations has a fall of 3°.
Equivalent
lengths (Leq)
Ø
Accessory Leq Min Length
Ø 60/100 45° elbow
Ø 60/100 90° elbow 2 m 0.375 m
Table 9
DANGER: Explosion!
▶ Always shut off the gas valve before
carrying out work on gas pipes.
The appliance installation, electrical
connection, gas connection, connection of
the flue system, and the initial start-up, are
operations to be carried out by authorised
technicians only.
NOTICE: Damage to the appliance!
▶ Do not place the device on the floor with
the connections facing downwards as
this may damage the appliance.
Installation in marine environments can lead
to premature corrosion. Premature
corrosion due to the installation environment
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 to determine if additional
delivery temperature control is required.

15
Installation (only by an authorised technicians)
Optiflow Professional – 6 720 810 560 (2017/11)
4.2 Choice of installation site
4.2.1 Regulations concerning the installation site
▶ The water heater may not be installed over a heat source.
▶ Comply with the minimum installation clearances indicated
in fig. 5 and table 10.
▶ Ensure there is a socket for electrical connection near the
water heater and it is easily accessible after the installation
of the water heater.
Location of the appliance
The combined air intake and flue terminal must terminate
outdoors in a well ventilated area away 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 containing chlorine and fluorine
compounds. They may be found in solvents, paints, adhesives,
aerosol propellants and household cleaners, for example.
If these conditions cannot be guaranteed, a different site must
be chosen for the appliance.
4.2.2 Overall flue length of the installation
The overall flue length may not exceed the values indicated in
the tables 7 and 8, and must not be less than the values
indicated in table 9 (Min length).
In determining the overall length of the installation, the
equivalent length (Leq) of each accessory must be considered.
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 cabinetry.
▶ Ensure that local building codes and regulations are
followed.
4.3 Minimum clearances
Consider the following limitations when determining the
installation location:
▶ Maximum length of the power cord.
▶ Allowances for service work while considering the
minimum distances indicated in fig. 6.
Fig. 5 Minimum distances
[A] Side1 cm
[B] 40 cm
[C] Front 2 cm
Minimum distances to exhaustion points
Fig. 6 Minimum flue clearances
In horizontal installations, the first elbow
positioned just at the outlet of the appliance
must not be considered for the purposes of
calculation.
Item Min.clea-
rance (mm)
A Below eaves, balconies and other
projections
300
BFrom the ground, above a balcony or other
surface1)
300
C From a return wall or external corner1) 300
Table 10
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

16
Installation (only by an authorised technicians)
Optiflow Professional – 6 720 810 560 (2017/11)
4.4 Fitting hanging-plate
No special wall protection is necessary. The wall has to be
capable of supporting the weight of the appliance.
▶ Find a suitable location.
▶ Drill the required holes.
▶ Fix the hanging plate using appropriate fixings (not
supplied).
4.5 Installing the appliance
▶ Remove the appliance from the packaging.
▶ Check that all the items indicated are included (section
2.3).
▶ 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.
4.6 Water connection
▶ Identify the cold and hot water pipe to avoid possible cross
connection.
▶ Install a pressure reducing valve if required. It's preferable
to install this valve close to the water meter.
▶ Complete the cold (fig. 2. [18]) and hot (fig. 2, [8]) water
connections.
4.7 Gas connection
The gas connection to the water heater must comply with the
AS/NZS5601.
▶ First ensure that the water heater corresponds to the gas
type available.
▶ Fit a gas isolation 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.
4.8 Installation of flue accessories
The instructions in the respective manual must be followed for
the installation of the accessories.
DFrom a gas meter (GM) 1000
E From an electricity meter or fuse box (P)2) 500
FFrom a drain pipe or soil pipe 75
G Horizontally from any building structure 1)
or obstruction facing a terminal
500
HFrom 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
KFrom 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
Appliances over 150 MJ/h input 1500
1) unless appliance is certified for closer installation
2) Prohibitedarea below electricity meter or fuse box extends
to ground level
Before fitting the hanging-plate, ensure that
the water, gas, and flue connections can be
installed in this area.
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.
Item Min.clea-
rance (mm)
Table 10
CAUTION:
▶ Never support or balance the water
heater on the water and gas
connections.
Packaging materials can be recycled.
DANGER:
Non-compliance with applicable legal
standards may cause, material damage,
personal injury, or even death.
Size gas supply as per AS/NZS5601.
Incorrect gas pipe sizing will not be covered
by the warranty.

17
Installation (only by an authorised technicians)
Optiflow Professional – 6 720 810 560 (2017/11)
▶ Once the connection of the flue is completed, ensure that
the seal is air tight.
Flue configuration
Bosch 4000S supplied flue must be used with these
appliances.
Cutting coaxial flue to length
When cutting flue to length please ensure that:
• All cuts are made on the male end of each flue component.
• The cuts are square (not on an angle) so that a complete
seal can be achieved on installation.
• The burrs are removed from the cut lengths of flue. If burrs
are not removed they may damage the internal seals in the
flue.
Maximum distance to the facade
In case of horizontal flue termination:
▶ Ensure that the distance between the end of the inlet air
pipe and the facade is no greater than 30 mm (Fig. 7).
Fig. 7 Dimensions
4.9 Altitude of installation site
To ensure correct operation of the appliance, at altitudes above
500m, the altitude setting must be adjusted.
▶ Enter the Service function (section 5.2).
Display will show “P2”.
▶ Press until the display shows “P4”.
▶ Press the button .
Display will show “E”.
▶ Press until the display shows “AS”.
▶ Press the button .
Display will show “1”.
▶ Press the button or and select the altitude of the
installation site according with table below.
DANGER: Install the flue gas pipe so that
there are no leaks!
▶ Non compliance with this requirement
may cause combustion gases to leak
through the appliance case and may
result in personal injury or death.
CAUTION:
Ensure that the flue is installed to the
requirements of AS/NZS5601.
Display Altitude
1 < 500 m
2500 m - 1 000 m
3 1 000 m - 1 500 m
41 500 m - 2 000 m
5 2 000 m - 2 500 m
6> 2500 m
Table 11

18
Installation (only by an authorised technicians)
Optiflow Professional – 6 720 810 560 (2017/11)
4.10 Electrical connection (only by authorised
technicians)
All the regulating, control and safety devices in the appliance
are factory supplied already connected and ready to operate.
4.10.1 Connecting the power cable
▶ Connect the power cable to a power socket.
4.11 Commissioning of the appliance
▶ Open the gas and water isolation valves and check the
tightness of all the connections.
When a hot water tap is turned on, the movement of water
through the flow sensor (fig. 2, [15]) 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, [18])
delivers gas to the burner.
• The burner ignites. Initially only a part of the burner is lit.
• The flame sensor rod (fig. 2, [2]) detects the flame.
• The temperature of the water is checked automatically by
the sensors. The appliance adjusts the gas flow and water
flow to achieve the temperature selected.
• Depending on the output required, the rest of the burner
will ignite.
Safety shut-down when the safety time is exceeded
If the appliance does not maintain a flame within the safety
interval stipulated, a safety shut-off is carried out.
Air in the gas supply line may cause a delay or difficulty when
igniting.
If the ignition attempt is unsuccessful after a period of time, the
safety devices block the operation of the appliance, and air 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-off
To put the appliance back into operation after a safety shut-off:
▶ Close all hot water taps.
▶ Reset the appliance by switching it off at the socket and
unplugging the cord.
4.12 Changing the setpoint limit temperature
(only for 55 °C preset appliances)
The maximum temperature is preset to 55 °C. If required it can
be increased to 60 °C or 70 °C.
▶ Enter the Service function (section 5.2).
Display will show "P2".
▶ Press until the display shows "P4".
▶ Press the button .
Display will show "E".
▶ Press until the display shows "SL".
▶ Press the button .
Display will show "55"
▶ Press until the display shows "60" or “70”.
▶ Press the button for 3 seconds.
The value flashes to confirm the new setpoint limit.
4.13 Delivery temperature calibration
If the delivery temperature at the closest hot water outlet to the
appliance does not match the setpoint it can be adjusted as
follows:
▶ Enter the Service function (section 5.2).
Display will show "P2".
▶ Press until the display shows "P4".
▶ Press the button .
Display will show "E".
▶ Press until the display shows "SC".
▶ Press the button .
Display will show "0"
▶ Press or to adjust the delivery temperature as
required.
The setpoint can be adjusted between -5 °C and +5 °C.
DANGER: Due to electric shock!
▶ Before carrying out work on electrical
components, disconnect the power
supply (230 V AC) (by isolating switch
and removing the power plug from the
electrical socket) secure against
unintentional reconnection.
The electrical connection must be done in
accordance with AS/NZS3000.
If the power cable is damaged, it must be
replaced with a Bosch supplied spare part.

19
Regulating the gas (only for authorised technicians)
Optiflow Professional – 6 720 810 560 (2017/11)
▶ Press the button for 3 seconds.
The value flashes to confirm the new setpoint limit.
Calibration example
5 Regulating the gas (only for authorised
technicians)
5.1 Factory settings
The data plate on the each appliance will show the factory
setting of that appliance.
Natural gas
Universal LPG
5.2 Service function
Accessing the service function
▶ Press and hold down at the same time , ,and
for 3 seconds.
Fig. 8 Service function
The display will show "P2".
The service function is now activated.
5.3 Adjusting the appliance
5.3.1 Access to the test points
▶ Remove the front of the appliance.
Fig. 9
[A] Air pressure test point
[B] Gas pressure test point
5.3.2 Adjusting the maximum flow (Parameter P1)
▶ Turn on the appliance using 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 [B].
Setpoint Water temp. at tap Calibration
50 °C 48 °C +2 °C
Table 12
The appliance must not be operated if the
dynamic connection pressure is less than
1.13 kPa or greater than 2.75 kPa.
The appliance must not be operated if the
dynamic connection pressure is less than
2.5 kPa or greater than 4.5 kPa.
DANGER:
▶ The operations described below must only
be carried out by an authorised service
technician.
A
B
-+
6720804089-11.1V

20
Regulating the gas (only for authorised technicians)
Optiflow Professional – 6 720 810 560 (2017/11)
▶ Loosen the test point screw of the air pressure test
point.[A]
▶ Connect the negative "-" side of the pressure gauge to the
air pressure test point.[A]
▶ Press until the display shows "P1".
▶ Press the button .
Display will show "E".
▶ Press until the display shows "L1".
▶ Press the button .
The appliance is now ready for adjustment of the maximum
gas flow.
▶ Open a hot water tap.
▶ Press or until the pressure gauge shows the
value indicated in tab. 13.
▶ Press for 3 seconds.
The displayed 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 complete.
5.3.3 Adjusting the minimum flow (Parameter P2)
▶ Press until the display shows "P2".
▶ Press the button .
Display will show "E".
▶ Press until the display shows "L2".
▶ Press the button .
▶ Open a hot water tap.
The appliance is now ready for adjustment of the minimum
gas flow.
▶ Press or until the pressure gauge shows the
value indicated in tab. 13.
▶ 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 will show the temperature selected.
▶ Disconnect the pressure gauge from the test points [A] and
[B].
▶ Tighten the shutter screws of the test points [A] and [B].
The adjustment of the minimum gas flow is complete.
5.3.4 Adjusting pressure at the burner (Parameter P0)
▶ Enter the service mode by pressing and holding down the
, , and buttons simultaneously for 3
seconds (section 5.2).
Display will show "P2".
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 maximum flow.
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.
Natural gas H Universal
LP gas
Øinjector GWH12 1.7 1.3
GWH16 2.0 + 1.7 1.5 + 1.3
GWH20
Dynamic
connection
pressure
(kPa)
GWH12
GWH16
GWH20
1.13 2.75
Burner
pressure
(kPa) - P0
GWH12
GWH16
GWH20
0.12
Differential
pressure of
the burner
MAX (mbar) -
P1
GWH12 5.1 - 5.5 6.3 - 6.7
GWH16 3.3 - 3.7 4.1 -4.5
GWH20 3.2 - 3.6 4.2 - 4.6
Differential
pressure of
the burner
MIN (mbar) -
P2
GWH12 0.6 - 0.9 0.8 -1.1
GWH16 0.6 - 0.9 0.8 - 1.1
GWH20 0.6 - 0.9 0.8 - 1.1
Table 13 Pressure of the burner
Burner pressure adjustment is only required
if “L1” and “L2” cannot be achieved
according to table 13.