USER INSTRUCTIONS &
CUSTOMER CARE GUIDE
Greenstar 24i junior / 28i junior
WALL HUNG GAS-FIRED CONDENSING COMBINATION BOILER
FOR SEALED CENTRAL HEATING SYSTEMS & DOMESTIC HOT WATER
THIS BOILER IS USED WITH
NATURAL GAS OR LPG (Cat II 2H3P TYPE C13, C33 & C53)
NATURAL GAS 24i junior GC NUMBER: 47 311 86
28i junior GC NUMBER: 47 311 87
LIQUID PETROLEUM GAS 24i junior GC NUMBER: 47 311 90
28i junior GC NUMBER: 47 311 91
CONTENTS
INTRODUCTION
DEDICATED TO HEATING COMFORT
SAFETY PRECAUTIONS
GENERAL NOTES
1
2
3
USING YOUR BOILER
CONTROLS
6
7
7
7
7
7
8
9
OPERATING THE BOILER
Switching the boiler on/off
Setting the central heating temperature
Controlling central heating
Frost protection
Controlling domestic hot water
Fault condition
MAINTENANCE
MAINTAINING YOUR BOILER
FAULT FINDING
FAULT OR BREAKDOWN
10
11
12
ENERGY SAVING
TIPS ON ENERGY SAVING
13
GUARANTEE
YOUR GUARANTEE
GUARANTEE REGISTRATION
15
16
Dedicated to heating comfort
Thank you for purchasing a Greenstar gas-fired condensing combination boiler
manufactured by Worcester, Bosch Group. The company prides itself on manufacturing
boilers to the strictest quality control standards throughout every stage of production.
Worcester, Bosch Group has led the field in innovative boiler design and performance
for more than 40 years. This heritage means all products are of exceptional quality and
proven reliability.
The Greenstar range in particular is extremely energy efficient, offering you economical
running costs and value for money. It sits in SEDBUK Band A, and is therefore
amongst the top energy rated boilers available.
There is also the reassurance of our no-nonsense 2 years parts and labour guarantee -
backed up by Worcester Total Cover, an optional complete maintenance scheme to
keep your boiler operating at peak condition and efficiency.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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CONTENTS
SAFETY PRECAUTIONS
IF YOU SMELL GAS!
ꢀ DO NOT SMOKE OR STRIKE MATCHES
ꢀ DO NOT TURN ELECTRICAL SWITCHES ON OR OFF
ꢁPUT OUT NAKED FLAMES
ꢁOPEN DOORS AND WINDOWS
ꢁKEEP PEOPLE AWAY FROM THE AREA AFFECTED
ꢁTURN OFF THE CONTROL VALVE AT THE METER
ꢁCALL YOUR GAS COMPANY
BOILER OPERATION:
This boiler must only be operated by a responsible adult who
has been instructed in, understands and is aware of the
boiler’s operating conditions and effects.
COMBUSTIBLE AND CORROSIVE MATERIALS
Do not store or use any combustible materials (paper, thinners, paints etc.) inside or
within the vicinity of the boiler.
Chemically aggressive substances can corrode the boiler and invalidate any warranty.
FITTING & MODIFICATIONS
Fitting the boiler, any controls to the boiler and removal of the outer casing may only
be carried out by a competent engineer in accordance with the Gas Safety
(Installation and Use) Regulations.
Flue systems must not be modified in any way other than as described in the
Installation instructions and any misuse or unauthorised modifications to the boiler,
flue or associated components and systems could invalidate the warranty. The
manufacturer accepts no liability arising from any such actions. This does not affect
your statutory rights.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
EXCELLENCE COMES AS STANDARD
8 716 115 661 (05/2009)
GENERAL NOTES
SERVICING
The boiler must be serviced regularly by a competent, qualified person, such as a
Worcester service engineer or alternatively a British Gas or other Gas Safe registered
person.
Always use original spares, to help maintain the economy, safety and reliability of the
boiler and to have the Service Record completed in the Benchmark checklist.
IMPORTANT:
Ensure that the service engineer completes the Service Record in
the Benchmark checklist after each service.
The completed Benchmark checklist will be required in the event of
any warranty work and may be required by the local Building Control
Inspector.
NOTE:
The Benchmark checklist and service interval record can be found at
the rear of the Installation, Commissioning and Servicing
Instructions.
BENCHMARK STANDARD
‘Benchmark’ is a code of practice for correctly installing, commissioning and servicing
of domestic water heating boilers.
A Benchmark Checklist is provided by the manufacturer for the installer to complete
ALL details together with their Gas Safe registration number and sign to confirm that
the boiler has been installed and commissioned according to the manufacturer’s
instructions.
HEALTH & SAFETY
The boiler contains no asbestos and no substances used in the construction process
that contravene the COSHH Regulations (Control of Substances Hazardous to Health
Regulations 1988).
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SAFETY PRECAUTIONS
GENERAL NOTES
To get the best from your boiler please
read these instructions carefully.
SEALED HEATING SYSTEMS
CLEARANCES - VENTILATED
COMPARTMENT
This boiler is fitted to a sealed heating
system which is pre-pressurised. Your
installer will advise you of the minimum
and maximum pressure which should be
indicated on the pressure gauge.
Your installer will have provided adequate
space around the boiler for safety and
servicing access. Do not restrict this
space with the addition of cupboards,
shelves etc. next to the boiler.
Check regularly that the pressure is
maintained and contact your installer or
maintenance engineer if a permanent
significant drop in pressure is indicated
on the pressure gauge. If the system
loses pressure it should be re-pressurised
and the cause of the fall investigated.
+ 30mm
above elbow
CENTRAL HEATING SYSTEMS
During the first few hours of operation of
the central heating system, check that all
radiators are being heated evenly. If the
top of a radiator is at a lower temperature
than the bottom then it should be vented
by releasing air through the venting screw
at the top of the radiator. Ask your
5mm
5mm
25mm*
600mm**
installer to show you how this is done.
This boiler is fitted to a sealed system;
repeated venting will reduce the quantity
of water in the system and this must be
replenished for safe and satisfactory
operation of the boiler.
200mm
*600mm service clearance required to a fixed surface
(**25mm from removable door or panel)
Should water leaks be found in the
system or if excessive venting is required,
then a service engineer must be
contacted to inspect the installation and
rectify any fault.
ROOM THERMOSTAT
A room temperature controller and
programmer should be fitted to control the
central heating. Refer to the instructions
supplied with the thermostat for
Only additives that are compatible with
aluminium may be used in the system. Any
incompatible additive used will invalidate
the guarantee.
information on siting and setting.
THERMOSTATIC RADIATOR VALVES
CONDENSATE DRAIN
It is recommended that this type of valve is
fitted to all but one of the radiators (or at
least those in the sleeping
accommodation). The remaining radiator,
which must be where the room thermostat
is located, should be un-controlled and
must be left open. The thermostatic
radiator valves should conform to the
requirements of BS2767:10.
This is a condensing boiler and the
terminal will, at times give out a plume of
water vapour. This is quite normal.
The boiler also produces quantities of
condensate which is discharged regularly
by a syphon within the boiler via a pipe to
drain. This pipe must not be blocked or
altered in any way.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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GENERAL NOTES
GENERAL NOTES
BOILER CLEARANCES -
UNVENTILATED COMPARTMENT
+ 30mm
above elbow
The diagram opposite shows the
minimum space required to install and
service the boiler inside an unventilated
compartment.
200mm*
** Space required for unventilated areas
with a removable door or panel.
200mm*
*** 600mm clearance required to a fixed
surface for servicing.
100mm**
600mm***
* The boiler must have more clearance in
the unventilated compartment compared
to the ventilated compartment.
Two examples are shown opposite, refer
to the “Installation, commissioning and
servicing instruction manual” for further
information.
Do not add cupboards, shelves etc. to
restrict the space around the boiler.
200mm
VENTILATION
This is a room sealed boiler and does not
require any air for combustion from inside
the property. If the boiler is fitted into a
cupboard or a compartment is built
around the boiler after installation, then
the compartment must be separated from
the boiler space by a perforated non-
combustible partition as described in BS
6798.
Notwithstanding the requirements of BS
6798 and BS 5440 there is no need for
ventilation openings to be provided in the
compartment because of the low heat
loss from the boiler casing, if the
**
***
clearances shown are maintained.
Do not operate the boiler if the flue
terminal fitted on the outside wall or roof
is obstructed or damaged.
PUMP ANTI-SEIZURE
If there has been no heating demand for
24 hours the boiler will run the system
pump for a few seconds to reduce the
possibility of pump seizure during long
periods of inactivity, which is usually more
frequent during the summer months.
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SAFETY PRECAUTIONS
CONTROLS
ꢀTo gain access to the boiler controls
push at the top of the flap and release.
7
3
4
5
6
1. CENTRAL HEATING
TEMPERATURE CONTROL
2. MAINS ON/OFF INDICATOR +
FAULT DIAGNOSTIC LIGHT
3. BURNER ON INDICATOR LIGHT
(GREEN)
4. ECO BUTTON (DOMESTIC HOT
WATER PRE-HEAT ON/OFF)
5. FAULT RESET BUTTON
6. SYSTEM PRESSURE GAUGE
7. POSITION FOR OPTIONAL
PROGRAMMER
1
2
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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CONTROLS
OPERATING THE BOILER
SWITCHING THE BOILER ON/OFF
Switching on
ꢀSwitch on the boiler at the mains supply,
the indicator light shows blue. There
should be no need to switch the boiler off
unless, in the unlikely event, a fault has
occurred.
Switching off
ꢀShould you need to switch off the boiler
then do so at the mains supply. The blue
indicator light goes out.
NOTE: When the boiler is switched off
frost protection is disabled.
SETTING THE TEMPERATURE
ꢀTurn the temperature control knob to
the desired level, approximate
temperatures for each setting are shown
in the table opposite.
When the burner is lit, the green burner
on indicator light is illuminated.
40°C
47°C
53°C
61°C
68°C
74°C
80°C
82°C
Min ---
1
2
3
4
5
6
---
---
---
---
---
---
CONTROLLING CENTRAL HEATING
ꢀSet the timer to the correct time.
ꢀSet room thermostat to the desired
room temperature.
ꢀSet the thermostatic radiator valves to
the desired settings.
Max ---
FROST PROTECTION
ꢀIn the event where the boiler is not to be
used for a period of time, leave power on
and turn the temperature control to
.
If the temperature falls below 5°C within
the boiler it will periodically fire to avoid
the possibility of freezing.
ꢀ
If remote pipework is exposed to
low temperatures, ensure that the
installer has added a frost
thermostat.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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OPERATING THE BOILER
OPERATING THE BOILER
HOT WATER TEMPERATURE
The hot water temperature is fixed at
55°C and can not be adjusted.
DOMESTIC HOT WATER PRE-HEAT
Pre-heat reduces the time taken to
produce hot water at the tap and is
controlled by the ECO button.
ꢀ
Press and hold the ECO button to
select either, not illuminated or
illuminated:
When the ECO button is not
illuminated the boiler will be in pre-
heat mode (which will reduce the time
taken to produce hot water at the tap).
OR
When the ECO button is illuminated
the boiler will be in ECO mode with no
pre-heat available.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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OPERATING THE BOILER
OPERATING THE BOILER
FAULT CONDITION
In the unlikely event of a fault occurring
while the boiler is in operation:
The reset button will flash once per
second and the mains indicator (blue
light) will flash at different speeds
dependent on fault.
ꢀTo reset boiler press the reset
button.
The reset button will no longer be
illuminated and the mains indicator will
stop flashing.
The boiler will function normally,
dependent on programmer and room
thermostat settings.
If the electrical power to the boiler has
been interrupted a “reset fault”
condition will exist. Reset the boiler as
described above.
If the fault remains and cannot be
cleared by pressing the reset button, or
if fault remains call:
ꢀ
Worcester, Bosch Group for
assistance, giving a description of
the fault and, if possible the fault
flashing sequence from the mains
indicator.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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OPERATING THE BOILER
MAINTAINING YOUR BOILER
Your new Greenstar gas-fired boiler represents a long term investment in a reliable, high
quality product.
In order to realise its maximum working life, and to ensure it continues to operate at
peak efficiency and performance, it is essential that your boiler receives regular
servicing and maintenance checks from a competent person beyond the initial 2 year
guarantee period.
If you would like to know more about a Worcester, Bosch Group service contract,
please tick the appropriate box on your warranty registration card.
If your Greenstar gas-fired boiler should fail to operate correctly or requires servicing
please contact the Worcester, Bosch Group Service Department (see inside front cover
for details).
Details of the boiler including the Gas Council number can be found under the controls
cover flap on the boiler.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
MAINTAINING YOUR BOILER
8 716 115 661 (05/2009)
FAULT FINDING
This table gives information on basic operating system problems.
In the unlikely event of a boiler fault please read the following page thoroughly
before contacting Worcester, Bosch Group.
Problem
Cause
Remedy
Desired room
temperature is not
reached
Thermostatic radiator
valve(s) set too low
Increase thermostatic
radiator valve setting(s)
Temperature control for
CH flow on boiler set too
low
Increase CH flow
temperature control
setting
Air trapped in heating
system
Bleed radiators and
recharge heating system
Desired room
temperature exceeded by
large amount
Radiators are too hot
Turn down thermostatic
radiator valves / room
thermostat
Reduce central heating
temperature on boiler
Heating stays on for too
long
Clock is incorrectly set
Momentary power failure
Check setting
No on/off indicator light
Switch off boiler at the
mains supply, wait a few
seconds then switch on
again
Check setting
Hot water temperature
too low
Programmer setting
Reduce flow rate at tap
Water flow at tap too high
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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FAULT FINDING
FAULT OR BREAKDOWN
This boiler is supported in the UK and Eire by Worcester, Bosch Group.
Specially trained, Worcester, Bosch Group Service Engineers are available to attend a
breakdown occurring on this boiler.
No charge will be made for parts and/or labour providing:
An boiler fault is found and the boiler has been installed within the past 24 months.
Reasonable evidence of this must be supplied on request. i.e. the Benchmark Checklist.
A call-out charge will be made where:
The boiler has been installed for over 24 months.
OR
Evidence cannot be provided that the first year service inspection has been carried
out (i.e. an entry in the Benchmark Checklist).
OR
Our Field Service Engineer finds no fault with the boiler (see Note).
OR
The cause of breakdown is misuse or with other parts of your plumbing/heating system, or
with equipment not supplied by Worcester, Bosch Group.
NOTE: NO BOILER FAULT IS FOUND ON OVER 30% OF SERVICE CALL OUTS.
Please read this guide carefully to gain a good understanding of the operation of your
boiler. In the case of a suspected fault, refer to the fault finding section of this guide.
If in doubt contact our Technical Support
In the event of an boiler fault or breakdown please contact our Service Department.
Your service administrator will arrange for an engineer to call with the minimum of delay;
under normal circumstances this will be from 1 - 3 working days (excluding weekends)
for priority breakdown situations (no hot water and/or heating).
Invoices for attendance and repair work carried out on this boiler by any third party will
not be accepted.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
FAULT OR BREAKDOWN
8 716 115 661 (05/2009)
TIPS ON ENERGY SAVING
HEATING ECONOMICALLY
The boiler is designed to provide a high level of comfort while keeping gas consumption
and the resulting environmental effect as low as possible. The gas supply to the burner
is controlled according to the level of demand for heat. The boiler continues to operate
with a low flame if the demand for heat reduces. The technical term for this process is
modulating control. Modulating control reduces temperature fluctuations and provides
even distribution of heat throughout the home. This means that the boiler may stay on
for relatively long periods but will use less gas than a boiler that continually switches on
and off.
CENTRAL HEATING SYSTEMS WITH ROOM THERMOSTATS/THERMOSTATIC
RADIATOR VALVES
The temperature control on the boiler should be set to the maximum rated temperature
of the central heating system.
The temperature of each room can be set individually (except primary room with the
room thermostat) using the thermostatic radiator valves.
ROOF INSULATION
Around 30% of the heat loss from a property is through the roof. Replace any old
insulation with new insulation, preferably of around 200mm thickness or more.
WINDOW FRAMES
Single glazed windows, particularly those with steel frames, can lose a great deal of
heat. Consideration should be given to replacement with PVCu or wooden framed
double glazed units.
CURTAINS
Lined curtains, or heavier full length curtains can provide excellent insulation. However,
always ensure that the curtains do not drape over radiators.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
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TIPS ON ENERGY SAVING
TIPS ON ENERGY SAVING
DRAUGHTS
Try to ensure that draughts around doors, windows, letterboxes and keyholes etc. are
reduced by using a suitable draught excluder. Warning - Do not block or seal any air
vents that are installed to ensure the central heating boiler operates safely.
ROOM THERMOSTATS
Reducing the setting of the room thermostat by 1°C can reduce fuel consumption by up
to 10%.
NEW CONTROL SYSTEMS
Upgrade your heating control system if necessary with the latest equipment available.
The minimum level of control is a programmer, interlocking room thermostat and
thermostatic radiator valves.
RADIATORS
More often than not radiators will be sited underneath a window, so the warm air from
the radiator heats the colder incoming air from the window. The performance of the
radiator will be affected if the curtains are allowed to drape over the radiator or shelves
are fitted above it. The positioning of furniture and tables in front of the radiator should
also be avoided.
It is advisable to manually adjust all radiator thermostatic valves every 2-3 months to
prevent them sticking. It is also important that the plastic tops of all valves are always in
position and not cracked or damaged to prevent accidents. Care should be taken when
vacuum cleaning carpets to avoid damage to valves and pipework.
The heating system and the outputs of the radiators have been carefully selected by
your installer. The temperature obtainable in any given room is dependent on all
radiators being operated at the same time. If you decide to turn off radiators in unused
rooms, spare bedrooms etc., you may experience slightly lower room temperatures in
rooms adjacent to unheated rooms.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
TIPS ON ENERGY SAVING
8 716 115 661 (05/2009)
YOUR GUARANTEE
This boiler is guaranteed against faulty material or workmanship for a period of 2 years
from the date of installation subject to the following terms and conditions:
ꢀ
Your Guarantee Registration Card must be returned within 30 days for the second
year of your guarantee to become valid.
ꢀ
During the period of this guarantee any components of the unit which are proven
to be faulty or defective in manufacture will be exchanged or repaired free of
charge by Bosch Thermotechnology Ltd.
ꢀ
The householder may be asked to prove the date of installation, that the boiler was
correctly commissioned and, where appropriate, the first year’s service inspection
has been carried out to the satisfaction of Bosch Thermotechnology Ltd., when
requested. These should be part of the Benchmark Checklist.
ꢀAny product or part returned for servicing under the guarantee must be
accompanied by a claim stating the model, serial number & date of installation.
ꢀ
Bosch Thermotechnology Ltd., will not accept responsibility for damage caused by
faulty installation, neglect, misuse or accidental damage or the non-observance of
the instructions contained in the Installation Commissioning and Servicing
Instructions and User Instructions and Customer Care Guide.
ꢀ
The boiler has been used only for the normal domestic purposes for which it was
designed.
ꢀ
This guarantee applies only to equipment purchased and used in the United
Kingdom and Eire.
This guarantee does not affect your statutory rights.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
8 716 115 661 (05/2009)
YOUR GUARANTEE
GUARANTEE REGISTRATION
You should complete and return the postpaid Guarantee
Registration Card within 30 days of purchase.
Returning the card will register you as the owner of your new
Greenstar i junior boiler and will assist us in maintaining an
effective and efficient customer service by establishing a
reference and permanent record for your boiler.
This does not affect your statutory rights.
For your own record:
Model
Serial No.
(See identity label inside boiler casing)
Type / size
Date of installation
Name of Installer
Telephone number of Installer
Please ensure that the Benchmark Checklist has been
completed by your installer or service engineer.
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WORCESTER BOSCH GREENSTAR 24i/28i Junior
8 716 115 661 (05/2009)
GUARANTEE REGISTRATION
NOTES
WORCESTER BOSCH GREENSTAR 24i/28i Junior
8 716 115 661 (05/2009)
USER INSTRUCTIONS &
CUSTOMER CARE GUIDE
Dedicated to heating comfort
Worcester, Bosch Group
Cotswold Way, Warndon, Worcester WR4 9SW.
Tel. 01905 754624 Fax. 01905 754619
Worcester Bosch Group is a brand name of Bosch Thermotechnology Ltd.
8 716 115 661 (05/2009)
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