Bosch TF250 Technical Document

Installation Manual and Operating Instructions
Continuous Flow Gas Water Heaters (External Models)
Pilot Ignition
TF250... | TF400...
6 720 886 398 (2021/02) AU

2
Table of contents
Pilot Ignition – 6 720 886 398 (2021/02)
Table of contents
1 Safety information and symbols . . . . . . . . . 3
1.1 Key to symbols . . . . . . . . . . . . . . . . . . 3
1.2 Safety information . . . . . . . . . . . . . . . 3
2 Technical Characteristics and Dimensions 5
2.1 General Description . . . . . . . . . . . . . . 5
2.2 Explanation of Model Code . . . . . . . . 5
2.3 Package contents . . . . . . . . . . . . . . . . 5
2.4 Description of the Hot Water Unit . . . 5
2.5 Dimensions . . . . . . . . . . . . . . . . . . . . . 6
2.6 Technical characteristics . . . . . . . . . . 7
3 Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1 Important information . . . . . . . . . . . . 8
4.2 Requirements of the installation
location . . . . . . . . . . . . . . . . . . . . . . . 10
4.3 Hot Water Unit mounting . . . . . . . . . 11
4.3.1 Flue baffle setting . . . . . . . . . . . . . . . 11
4.3.2 Mounting the heater . . . . . . . . . . . . . 11
4.4 Water connection . . . . . . . . . . . . . . . 12
4.5 Gas connection . . . . . . . . . . . . . . . . . 12
4.6 Testing . . . . . . . . . . . . . . . . . . . . . . . . 12
5 Commissioning 10 litres appliances . . . . . 13
5.1 Before starting up the heater . . . . . . 13
5.2 Remove the front cover . . . . . . . . . . 13
5.3 Inlet pressure adjustment . . . . . . . . 13
5.4 Burner pressure adjustment . . . . . . 13
5.5 Conversion to a different
type of gas . . . . . . . . . . . . . . . . . . . . 14
6 Commissioning 16 litres appliances . . . . . 15
6.1 Before starting up the heater . . . . . . 15
6.2 Remove the front cover . . . . . . . . . . 15
6.3 Water flow adjustment . . . . . . . . . . . 15
6.4 Inlet operating pressure adjustment 15
6.5 Burner pressure adjustment . . . . . . 16
6.6 Thermostat calibration . . . . . . . . . . . 16
6.7 Conversion to a different
type of gas . . . . . . . . . . . . . . . . . . . . 16
7 Operating instructions . . . . . . . . . . . . . . . . . 17
7.1 Procedure to light 10 Litres
appliance . . . . . . . . . . . . . . . . . . . . . 17
7.1.1 Lighting the appliance . . . . . . . . . . . 17
7.1.2 Output control . . . . . . . . . . . . . . . . . 17
7.1.3 Consumer temperature/flow
adjustment . . . . . . . . . . . . . . . . . . . . 17
7.1.4 Shutting OFF the appliance . . . . . . . 17
7.2 Procedure to light 16 Litres
appliance . . . . . . . . . . . . . . . . . . . . . 18
7.2.1 Lighting the appliance . . . . . . . . . . . 18
7.2.2 Shutting OFF the appliance . . . . . . . 18
8 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . 19
9 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . 20
9.1 Problem/cause/solution . . . . . . . . . 20
10 Environmental protection . . . . . . . . . . . . . . 22
11 Water quality . . . . . . . . . . . . . . . . . . . . . . . . . 22
12 Warranty details . . . . . . . . . . . . . . . . . . . . . . 23

3
Safety information and symbols
Pilot Ignition – 6 720 886 398 (2021/02)
1 Safety information and symbols
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:
▶ Close the gas supply valve to the
appliance.
▶ Isolate gas supply from gas meter or
LPG bottle.
▶ Do not operate any electrical
appliances or switches (on/off).
▶ Extinguish other sources of ignition.
▶ Go to a different location and call the
gas supplier or an authorised
technician in order to check the gas
supply.
If you notice dark combustion gases
or sooting:
▶ Isolate the Gas supply to the heater.
▶ Notify an authorised technician.
Installation, Assembly and
Modifications
▶ The installation, assembly and
modifications to the heater must only
be performed by an authorised
installer.
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.
▶ The Owner/User is responsible for
keeping the area around the water
heater free from debris.
▶ Safe access to inspect and service the
water heater is the responsibility of
the property owner.
▶ Only original spare parts must be
used, supplied by an authorised
distributor of Genuine Bosch parts.
Explosive and highly flammable
material
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
Safety information and symbols
Pilot Ignition – 6 720 886 398 (2021/02)
▶ Do not use or store flammable
materials in or near this appliance.
Combustion air and surrounding air
▶ To avoid corrosion, the combustion
air and surrounding air must be free
from harmful substances.
▶ Do not spray aerosols in the vicinity of
this appliance while it is in operation.
Risk of damage due to operator error
Operator errors can result in injury and
damage to property.
▶ Ensure that children never operate
this appliance unsupervised.
▶ 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.
Tobe installed andservicedonly 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, SPA POOL OR SOLAR BOOSTER
APPLICATION.
NOT SUITABLE FOR COMMERCIAL
BOOSTING OF A WARM WATER
RECIRCULATION SYSTEM.
Do not modify this appliance.
WARNING:
This appliance may deliver
water at high temperature.
Refer to the Plumbing Code pf
Australia (PCA), local
requirements and installation
instructions to determine if
additional delivery
temperature control is
required.

5
Technical Characteristics and Dimensions
Pilot Ignition – 6 720 886 398 (2021/02)
2 Technical Characteristics and Dimensions
2.1 General Description
The appliance has been AS/NZS 5263.1.2 tested.
2.2 Explanation of Model Code
2.3 Package contents
•Gashotwaterunit
• Documentation
2.4 Description of the Hot Water Unit
• Hot Water Unit for external wall-mounting only
• Available in Natural gas or LP gas
•Safetydevices:
– Thermocouple to check for accidental extinction of the
pilot flame
– Overtemperature switch to prevent overheating.
• Water filter on the inlet water supply
Economical
Only heating water when required, the Bosch range is
extremely economical to run.
Versatile
LPG models are particularly popular in country areas, where
Natural Gas is not available.
Low Temperature Areas
In areas where the atmospheric temperature may drop to 0 °C
for brief periods, the installation of an EXOGEL valve (part
number H707 060 151) will minimise the possibility of
damage to the appliance if the water freezes.
Fig. 1 EXOGEL valve
[1] Hot water
[2] Cold water
[3] EXOGEL valve
Low Flow Rates
This gas water heater is designed to operate at a minimum flow
rate between 3.2 to 4.0 litres per minute. Sufficient flow must
be provided to ensure the correct operation of the appliance.
There are various causes of a low flow rate including, but not
limited to:
•Lowflowtapware
• Flow restrictors/aerators
•Handheldshowers
• Poor inlet pressure to property
• Restrictive pipework and/or fittings
Water fixtures and appliance settings must ensure that the flow
rate of hot water does not fall below the minimum requirement.
Failure of the unit to operate correctly due to poor flow rate will
not be covered by warranty.
Models TF250/400
Category CONTINUOUS FLOW
Type GAS - EXTERNAL INSTALLATION
Table 2
TF (Top Flue) 250 (10 litres/min @ 25 °C Rise)
TF (Top Flue) 400 (16 litres/min @ 25 °C Rise)
Table 3
NOTICE:
This water heater MUST NOT be installed in
areas where the temperature remains below
0 °C for extended periods.

6
Technical Characteristics and Dimensions
Pilot Ignition – 6 720 886 398 (2021/02)
2.5 Dimensions
Fig. 2
[1] Top flue
[2] Front cover
[3] Inspection window
[4] Wall mounting point
[5] Cold water inlet
[6] Gas inlet
[7] Hot water outlet
[8] Access panel
Dimensions (mm) A B C D E Weight (kg)
TF250 405 845 533 240 100 21
TF400 460 936 533 240 100 25
Table 4 Dimensions

7
Technical Characteristics and Dimensions
Pilot Ignition – 6 720 886 398 (2021/02)
2.6 Technical characteristics
Technical characteristics Units TF250... TF400...
Gas Consumption
Nominal Gas Consumption MJ/h 82 130
Ø burner injector mm 1.20 (NG)
0.75 (LPG)
1.30 (NG)
Supply pressure flowing
Natural gas (When operating) kPa 1.13 1.13
LP gas (When operating) kPa 2.6 2.6
Number of injectors 12 18
Water data
Maximum permissible pressure (Static) kPa 1200 1200
Temperature selector in fully clockwise position
Temperature rise (Above incoming water temperature) °C 55 _
Water flow range (Litres per minute) l/min 3.5 to 4.5 _
Minimum operating water pressure kPa 30 (NG)
10 (LPG)
_
_
Minimum constant water pressure for minimum flow kPa 60 _
Temperature selector in fully anti-clockwise position
Temperature rise (Above incoming water temperature) °C 25 _
Water flow range (Litres per minute) l/min 4 to 10 _
Minimum operating water pressure kPa 45 _
Minimum constant water pressure for maximum flow kPa 90 (NG)
55 (LPG)
_
Table 5

8
Regulations
Pilot Ignition – 6 720 886 398 (2021/02)
3Regulations
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.
This appliance must not be installed indoors or in an enclosed
space. This appliance is approved for outdoor installation only.
Failure to install this appliance in accordance with these
installation instructions will void the warranty and may create
an unsafe situation.
4 Installation Fig. 3 Minimum heat shield requirements
DANGER:
This appliance must not be installed indoors
or in an enclosed space in accordance with
AS/NZS5601.
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 air entry openings at the
front, rear, side, or top.
▶ Periodic checking of openings to ensure
no blockage or obstruction of the air
openings from plants, debris, or insects
must be carried out.
DANGER: Property damage!
If this appliance is to be installed on a
combustible surface:
▶ Use a heat shield as per AS/NZS5601.
The installation and the initial startup are to
be carried out only by an authorised person.
Not suitable for pool, spa pool, or solar
booster application.
Not suitable for commercial boosting of a
warm water recirculation system.
This appliance should only be installed in
applications where incoming cold water
temperature does not exceed 40 °C.
Minimum water supply pressure must meet
the requirements set out in table 5.
Water fixtures and appliance settings must
ensure that the flow rate of hot water does
not fall below the minimum requirement.
To reduce the chance of corrosion,
installation in a marine environment should
be avoided. Premature corrosion due to the
installation environment would not be
covered by warranty.
400 mm
850 mm
230 mm
=
9708069951-12.1V
=

9
Installation
Pilot Ignition – 6 720 886 398 (2021/02)
4.1 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. If the unit isto be installed
on a combustible surface, use a heat shield. Allow a
minimum air gap of 10mm between the flue and the heat
shield.
▶ Unit must be commissioned upon installation.
▶ Ensure the mounting structure is capable of supporting the
weight of the appliance once installed. Secure the
appliance 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 heater. Only use 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.
(table 5).
▶ If the inlet water pressure exceeds 800 kPa, a pressure
limiting valve (500 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.
▶ Refer to 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
performed with the gas isolation valve of the appliance
closed.
▶ Ensure the gas pressure and flow through the regulator are
appropriate for the consumption of the heater (table 5).
Refer to AS/NZS5601 and AS3500.1 for the relevant pipe
size.
▶ As the water temperature at the outlet may exceed 50 °C, a
temperature limiting device (such as a tempering valve)
must be fitted to pipework feeding sanitary fixtures used
for the purpose of personal hygiene as per AS3498.
Note: Incorrect pipe sizing or gas supply pressure may cause
the appliance to underperform. Service calls for incorrect pipe
sizing and/or gas pressure, will NOT be covered under
warranty.
All gas appliances require adequate air
intake 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.

10
Installation
Pilot Ignition – 6 720 886 398 (2021/02)
4.2 Requirements of the installation location
• Comply with the specific instructions for each State.
• Install the appliance in an outdoor location where it will not
be exposed to temperatures below zero.
• Install the appliance in accordance with the minimum
installation clearances indicated in Fig. 4, according to
AS/NZS5601.
• The gas heater must not be installed over a heat source.
• Location must allow for safe servicing and customer
operation.
• Side clearances to be measured from flue outlet, not wind
baffles.
• Do not obstruct the openings at top, bottom and rear of
appliance.
• Maximum of 2 meters from the ground to the base of the
appliance.
• Top and bottom areas must be clear from any obstacles at
least 30 cm.
Fig. 4 Minimum clearances (use as a guide only, always refer to AS/NZS5601)
[D] Openable Door
[T] Flue terminal
[M] Gas meter
[I] Mechanical air inlet
[P] Electricity meter or fuse box
[W] Openable window
c
j
j
d
a
n
b
ef
h
g
k
W
T
M
T
I
P
D
9708069951-14.2V
Ref. Item Minimum
clearances (mm)
a Below eaves, balconies and other projections:
- Appliances over 50 MJ/h input 500
b From the ground, above a balcony or other surface1) 300
cFrom a return wall or external corner1) 500
Table 6

11
Installation
Pilot Ignition – 6 720 886 398 (2021/02)
Combustion gases
4.3 Hot Water Unit mounting
4.3.1 Flue baffle setting
The flue baffle located on the side of the flue terminal must be
extended fully to ensure correct operation.
To extend baffle loosen the retaining nut and pull the baffle until
it is fully extended. Tighten retaining nut.
Fig. 5 Flue baffle setting
4.3.2 Mounting the heater
▶ Fix the appliance vertically, using the fixings appropriate
for the wall material and appliance weight.
d From a gas meter (M) (see 5.11.5.9 of AS/NZS5601 for vent terminal location of regulator) 1000
eFrom an electricity meter or fuse box [P] 500
f From a drain pipe or soil pipe 150
gHorizontally from any building structure1) or obstruction facing a terminal 500
h From any other flue terminal, cowl, or combustion air intake [T]1) 500
jHorizontally from an openable window, door, non-mechanical air inlet, or any other opening into a building with the
exception of sub-floor ventilation [W] [D] [T]:
- Appliances up to 150 MJ/h input 500
kFrom a mechanical air inlet, including a spa blower [I] 1500
n Vertically below an openable window, non-mechanical air inlet, or any other opening into a building with the exception of
sub-floor ventilation [W] [T]
- Appliances over 50 MJ/h input and up to 150 MJ/h input 1000
1) Unless appliance is certified for closer installation
Ref. Item Minimum
clearances (mm)
Table 6
Observe/comply with the minimum
clearances as in AS/NZS5601.
CAUTION:
Property damage!
▶ Never rest the gas heater on the water or
gas connections.
Draw a cross in the wall (Fig. 6, [A]) to
identify the appliance upper right corner
positioning.

12
Installation
Pilot Ignition – 6 720 886 398 (2021/02)
Fig. 6 Heater mounting
[A] Appliance upper right corner position
4.4 Water connection
Purge the water pipes before connection, because the
presence of dirt may reduce the flow and, in extreme cases,
cause a blockage.
▶ Identify the cold water pipe and the hot water pipe, so as to
avoid any possible cross-connection.
▶ Check and ensure water filter cleanness.
Fig. 7 Water connection
[A] Hot Water Outlet
[B] Cold Water Inlet
4.5 Gas connection
Gas regulator
The appliance is supplied with a gas pressure regulator already
installed. A regulator must be fitted to LPG cylinders to supply
the correct pressure to the appliance regulator.
The gas pressures require setting upon installation.
4.6 Testing
▶ Turn on the gas and water valves and check all connections
for leaks. If all connections are sound then follow
procedures set out in Section 5 for adjustment of Gas
Pressures to complete appliance commissioning.
CAUTION:
Isolating valve on the water inlet line must be
a Gate or ¼ turn full flow Ball Valve. A Stop
Valve, Duo Valve or Non-Return Valve must
not be fitted.
DANGER:
If local regulations are not followed, a fire or
explosion could result causing property
damage, personal injury, or loss of life.
Size gas supply as per AS/NZS5601.
Incorrect gas pipe sizing will not be covered
by the warranty.
▶ Open all water and gas isolation valves.
▶ Purge the pipes.

13
Commissioning 10 litres appliances
Pilot Ignition – 6 720 886 398 (2021/02)
5 Commissioning 10 litres appliances
5.1 Before starting up the heater
5.2 Remove the front cover
▶ Loosen the two knurled screws located on the rear side of
the front panel.
Fig. 8 Front cover removal
5.3 Inlet pressure adjustment
Gas pressure adjustment (commissioning) MUST be carried
out upon installation.
▶ Check the gas indicated on the data plate and label on the
front flue panel is the same as to which the gas is
connected.
▶ Turn off the gas to the appliance, remove the sealing screw
of the pressure test point on the right hand side of the gas
valve (Fig. 9, [A]) and attach a manometer.
▶ Turn on gas and light the pilot.
Static Pressures should be greater than or equal to the figures
in table 7.
▶ Adjust the appliance regulator to achieve the figures in
table 7 with the unit operating and several hot water taps
open for full water flow through the unit.
If the operating inlet pressure cannot be achieved there may be
an issue with the gas supply meter (NG), cylinder regulator
(LPG), or pipe sizing (Ref AS/NZS5601). This must be resolved
before proceeding.
▶ Remove manometer and tighten test point screw.
Fig. 9 Inlet measurement test point
5.4 Burner pressure adjustment
▶ Loosen the burner test point captive screw (Fig. 10
[D]).
▶ Connect a manometer to the burner pressure measuring
point.
Commissioning MUST be carried out upon
installation.
CAUTION:
▶ Initial startup must be performed by an
authorised gas fitter who will provide the
customer with all the necessary
information for optimum operation of
the gas heater.
DANGER:
The following procedures must only be
performed by a qualified technician.
Measurements should be made with unit
operating with several hot water taps
opened to achieve maximum water flow
through the unit.
If possible all other gas appliances (ducted
heating etc.) should be operating at the same
time.
Natural gas LP gas
Inlet Pressure
(kPa) TF250 1.13 kPa 2.6 kPa
Table 7 Inlet pressure

14
Commissioning 10 litres appliances
Pilot Ignition – 6 720 886 398 (2021/02)
Fig. 10 Burner pressure test point
▶ Turn on gas to the appliance and relight the pilot.
▶ Ensure water control knob is wound fully clockwise
(minimum flow) and gas control slide set to the right
(maximum gas flow).
▶ Turn on the water heater with several hot taps open.
▶ Adjust burner pressure to slightly below the burner
pressure figure on the data plate (table 8). Loosen the
locking screw (Fig. 11 [F]), and turn the knurled
adjustment wheel (Fig. 11 [E]) clockwise to increase, or
anticlockwise to decrease the pressure.
▶ Raise burner pressure to the burner pressure figure (See
table 8).
▶ Tighten locking screw of knurled adjustment wheel
(Fig. 11[F]).
▶ Turn off water heater, remove manometer and tighten
burner test point captive screw.
Fig. 11 Burner pressure adjustment
5.5 Conversion to a different type of gas
It is not recommended to convert these units to a different type
of gas.
Natural gas LP gas
Max. Burner
Pressure (kPa) TF250 0.87 kPa 2.4 kPa
Table 8 Burner pressure
D
9708069951-9.1V

15
Commissioning 16 litres appliances
Pilot Ignition – 6 720 886 398 (2021/02)
6 Commissioning 16 litres appliances
6.1 Before starting up the heater
6.2 Remove the front cover
▶ Loosen the two knurled screws located on the rear side of
the front panel.
Fig. 12 Front cover removal
6.3 Water flow adjustment
▶ Open a hot tap fully that can provide at least 16L/min.
-or-
▶ Disconnect outlet and attach a ball valve and pipe to
regulate and allow full flow.1)
▶ Adjust the slotted screw on the base of the water valve
(Fig. 13, [A] to set the flow rate to 16L/min.
▶ Turn screw clockwise to reduce pressure, anticlockwise to
increase.
Fig. 13 Water flow adjustment screw
6.4 Inlet operating pressure adjustment
▶ Check the gas indicated on the data plate and label on the
front flue panel is the same as to which the gas is
connected.
▶ Turn off the gas to the appliance, remove the sealing screw
of the pressure test point on the right hand side of the gas
valve (Fig. 14, [B]) and attach a manometer.
▶ Turn on gas and light the pilot.
Static Pressures should be greater than or equal to the figures
in table 9.
▶ Adjust the appliance regulator to achieve the figures in
table 7 with the unit operating and several hot water taps
open for full water flow through the unit.
If the operating inlet pressure cannot be achieved there may be
an issue with the gas supply meter (NG), cylinder regulator
(LPG), or pipe sizing (Ref AS/NZS5601). This must be resolved
before proceeding.
▶ Remove manometer and refit sealing screw.
Commissioning MUST be carried out upon
installation.
CAUTION:
▶ Initial startup must be performed by an
authorised gas fitter who will provide the
customer with all the necessary
information for optimum operation of
the gas heater.
1) Alternate method hint.
Measurements should be taken with unit
operating and 16l/min running through the
unit.
If possible all other gas appliances (ducted
heating etc.) should be operating at the same
time.
Natural gas LP gas
Inlet Pressure
(kPa) TF400 1.13 kPa 2.6 kPa
Table 9 Inlet pressure

16
Commissioning 16 litres appliances
Pilot Ignition – 6 720 886 398 (2021/02)
Fig. 14 Inlet measurement test point
6.5 Burner pressure adjustment
▶ Loosen the burner test point captive screw (Fig. 15,
[D]).
▶ Connect a manometer to the burner pressure measuring
point.
Fig. 15 Burner pressure test point
▶ Turn on gas to the appliance and relight the pilot.
▶ Turn on the water heater with full flow (16l/min).
▶ Using the appliance regulator, adjust the burner pressure
to the burner pressure figure on the data plate (table 10).
▶ Turn off water heater, remove manometer and tighten the
burner test point screw.
6.6 Thermostat calibration
▶ Using a flow cup, adjust the flow rate using the hot tap (or if
using alternate method, use ball valve on outlet) to 6l/min.
▶ Allow unit to run for 1 minute and using a thermometer,
measure the hot water temperature. Required temperature
is 60 °C.
▶ To make adjustments, loosen the locking nut (fig. 16 [C])
and turn the thermostat adjustment nut (fig. 16 [D])
clockwise to decrease temperature, and anticlockwise to
increase, to achieve the required 60 °C.
▶ Reduce the water flow rate to 3l/min, allow the unit to run
for 1 minute, and ensure temperature does not rise above
63 °C. If it does, reduce temperature slightly by the
adjustment nut.
▶ Tighten the locking nut.
The recommended operating temperature is 55 °C.
▶ Open the tap fully, reduce and adjust the flow rate using the
water flow adjustment screw on the base of the water valve
to achieve 55 °C.1)
▶ Check all gas points with soap solution.
Fig. 16 Thermostat adjustment
6.7 Conversion to a different type of gas
It is not recommended to convert these units to a different type
of gas.
Natural gas LP gas
Max. Burner
Pressure (kPa) TF400 0.71 kPa 2.4 kPa
Table 10 Burner pressure
D
9708069951-9.1V
1) 16l/min is based on a 25 °C temperature rise.

17
Operating instructions
Pilot Ignition – 6 720 886 398 (2021/02)
7 Operating instructions
7.1 Procedure to light 10 Litres appliance
7.1.1 Lighting the appliance
▶ Press button fully and keep it pressed.
Fig. 17
▶ After a few seconds press igniter button.
Fig. 18
▶ Release button after approx. 10 seconds.
If the flame does not stay alight.
▶ Repeat the steps above.
If the flame stay alight
▶Press“ON”button.
Fig. 19
7.1.2 Output control
For higher water temperature (Fig. 20).
▶ Slide to the right will give higher water temperature but use
more gas.
For lower water temperature (Fig. 20).
▶ Slide to the left will give lower water temperature and use
less gas.
Fig. 20
7.1.3 Consumer temperature/flow adjustment
▶Turnanti-clockwise
Increases flow and decreases water temperature (Fig. 21).
Fig. 21
▶Turnclockwise.
Decreases flow and increases water temperature.
Regulating the temperature to the minimum required value
reduces energy consumption.
7.1.4 Shutting OFF the appliance
If no hot water is to be drawn for a longer period of time.
▶ Press OFF button (Fig. 22).
Fig. 22
6720886398-002.1
6720886398-003.1
6720886398-004.1
Turn hot water tap on fully when using.
Low
flame
High
flame
6720886398-005.1

18
Operating instructions
Pilot Ignition – 6 720 886 398 (2021/02)
7.2 Procedure to light 16 Litres appliance
7.2.1 Lighting the appliance
▶ Press button fully and keep it pressed.
Fig. 23
▶ After a few seconds press igniter button.
Fig. 24
▶ Release button after approx. 10 seconds.
If the flame does not stay alight.
▶ Repeat the steps above.
If the flame stay alight
▶Press“ON”button.
Fig. 25
7.2.2 Shutting OFF the appliance
If no hot water is to be drawn for a longer period of time.
▶ Press OFF button (Fig. 26).
Fig. 26
6720886398-002.1
6720886398-003.1
6720886398-004.1

19
Maintenance
Pilot Ignition – 6 720 886 398 (2021/02)
8Maintenance
To ensure ongoing performance and safety, we require the
appliance be serviced every two years.
▶ Only use original replacement parts.
DANGER:
Failure to perform maintenance procedures
can lead to appliance malfunction, errors,
service calls and loss of manufacturers
warranty.
Maintenance must only be performed by a
qualified technician. Maintenance
information is contained in a service manual
available to licenced technicians upon
request from Bosch.
Service checklist Done
1. Water Valve
1.1 Diaphragm, replace if required.
1.2 Water throttle, greased, O-ring replaced if
required.
1.3 Water filter, cleaned, replace if required.
1.4 Gland oring, greased, replace if required.
1.5 Water governor, replace if required.
1.6 Slow ignition, cleaned.
2. Gas Valve
2.1 Pilot burner, cleaned.
2.2 Main burner, injectors and venturies cleaned.
2.3 Control buttons, greased.
2.4 Piezo ignitor, greased.
3. Heat Exchanger
3.1 Fins cleaned.
3.2 Water connections tightened.
4. Gas pressure
4.1 Burner pressures checked and adjusted.
Table 11 Service checklist

20
Troubleshooting
Pilot Ignition – 6 720 886 398 (2021/02)
9Troubleshooting
9.1 Problem/cause/solution
Assembly, maintenance, and repairs must be performed by
qualified technicians only. The following chart offers possible
solutions to problems.
In most instances it is advisable to have a technician attend and
inspect the appliance.
Some further trouble shooting advice may be found at http://
www.bosch-thermotechnology.com.au
Problem Cause Solution
Appliance does not light. Gas supply turned off.
Appliance blocked.
Check mains gas supply is turned on at
mains / cylinder supply. (Are other gas
appliances working?)
Is the gas isolation valve is turned on at
appliance.
Requires a service by a qualified
technician.
Pilot lights but no main burner. Main burner button not pushed in.
Water throttle wound out too far.
Service required
Push in, refer to relight section.
Wind clockwise, refer to temperature
adjustment section.
Contact a qualified technician.
Smell of gas. Gas leak. Isolate gas supply to hot water unit.
Contact a qualified technician.
Yellow flame/strong smell of gas in
operation/presence of soot.
This is normally caused by blockages in
the burner causing poor combustion.
One of the causes of blockages is insects
in the burner.
All gas appliances required adequate air
flow for combustion. The ingress of
insects or dirt into the unit are not
covered by warranty, as a manufacturing
fault is not present.
The unit will require cleaning and
servicing at the owners cost.
To minimise the chance of the issue
recurring, a surface type insecticide can
be used with care, consultation with a
licensed pest controller is recommended.
Isolate the valves to the appliance and
spray surrounds with a surface spray.
Leave for 15 minutes before relighting.
Table 12