Worcester GREENSTAR 24i junior User manual

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24i, 28i RSF COMBI
USER INSTRUCTIONS &
CUSTOMER CARE GUIDE
G.C. NUMBERS
NATURAL GAS L.P.G.
24i 47 311 37 47 311 38
28i 47 311 54

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EXCELLENCE COMES
AS STANDARD
Thank you for purchasing a Worcester gas-fired
combination appliance.
Worcester appliances are made by Worcester Heat Systems
and the strictest quality control standards are demanded
throughout every stage of production.
Indeed, Worcester Heat Systems have led the field in
innovative appliance
design and performance
for more than 30 years.
The result is that your
new Worcester 24i or 28i
appliance offers you the
very best of everything –
quality, efficiency,
economical running costs,
proven reliability and
value for money.
What’s more, you also
have the assurance of our
no-nonsense 1 year parts
and labour guarantee.
And it’s backed up by Worcester Care Call – a complete
maintenance scheme to keep your boiler operating at peak
condition and efficiency.
No wonder that more and more people are agreeing that
when it is gas, it has to be a Worcester 24i or 28i
Page No.
Operating Instructions
.................................... 3-11
Fault and Breakdowns 12
Maintenance and
Extended Warranty
Information ............ 13-14
Guarantee Details ... 15-16
CONTENTS
2

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GENERAL
INFORMATION
GAS SAFETY (INSTALLATION AND USE)
REGULATIONS 1998
It is the law that all gas appliances must be installed by a
competent person in accordance with the above regulations. Failure to
install appliances correctly could lead to prosecution. It is in your
interest and that of safety to ensure compliance with the law. The
manufacturers notes must not be taken, in any way, as over-riding
statutory obligations.
WARNING: This appliance must be earthed and protected by a 3
amp fuse.
ELECTRICITY SUPPLY: 230V ~ 50Hz
IMPORTANT: To get the best from your Worcester appliance
please read these instructions carefully.
NOTE: In the event of a fault the appliance should not be used
until the fault has been corrected by a competent person.
BENCHMARK
All CORGI Registered Installers carry a CORGI ID card and have
a registration number which must be recorded in your central heating
log book. You can check that your installer is CORGI registered by
calling CORGI on 01256 372300.
GENERAL DESCRIPTION
(See Fig.1.)
The WORCESTER 24i or 28i is a combined domestic hot water
and central heating appliance. It consists of a gas fired boiler having a
varying output of between 7.5 kW and 23.4 kW (24i) or 8.5 kw and
27.5 kw (28i), a combined heat-exchanger and all necessary controls to
provide mains fed domestic hot water and central heating.
The appliance can operate in one of two modes as required. Hot
water only or hot water and central heating.
Hot Water Mode:
When a demand is made for hot water by opening a tap or
shower the flow switch will energise and the burner will light at its
maximum setting.
When hot water is no longer required the appliance pump and
fan may continue to operate to dissipate the excess heat within the
boiler.
3

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4
A flow restrictor is fitted within the appliance which limits the
hot water delivery rate to a maximum of 8.0 (±15%) litres/minute
(1.8 gallons/minute) 24i or 10 (±15%) litres/minute (2.2 gallons/minute)
28i.
Hot Water and Central Heating mode:
When a demand is made for heating by the system controls (i.e. a
programmer or room thermostat).
The pump will energise circulating primary water around the
heating system and the burner will light. The heat output from the
appliance in this mode has been factory set to maximum. The
appliance will operate as necessary to maintain the temperature of the
radiators at the level set by the adjustment of the Heating
Temperature Control Knob.
(See Fig. 2.)
If the system no longer
requires output to maintain
the desired room temperature,
the burner will extinguish.
The pump and fan will
continue to run for a short
period to dissipate the
residual heat from the
appliance and then switch off.
The appliance will supply
heat to the central heating
system as required. A demand
for hot water at a tap or
shower will override the
central heating function for
the period of the domestic hot
water demand.
Fig. 1. System Diagram.
Automatic
air vent
Gas to water
heat
exchanger
Circulating
pump
Fixed
by-pass
Flow
switch
CH
return
Domestic
hot water
out Domestic
cold
supply
Safety
discharge
Pressure
relief valve
Boiler
Expansion
vessel
CH
flow

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5
CENTRAL HEATING SYSTEM
During the first few hours of operation of the central heating
system, check that all radiators are being heated at an even rate.
Should the upper area of a radiator be at a lower temperature than the
base of the radiator, it should be vented by releasing air through the
venting screw at the top of each radiator. Make sure your installer
shows you how to carry out the operation. Repeated venting will
reduce the quantity of water in the system and this must be
replenished for safe and satisfactory operation of the appliance.
Should water leaks be found in the system or excessive venting be
required from any radiator, a service engineer should be contacted and
the system corrected.
SEALED HEATING SYSTEM
The appliance will be fitted to a sealed heating system which is
pre-pressurised. Your installer will advise you on the minimum and
maximum pressure that should be indicated on the pressure gauge.
See Fig. 2. Check regularly that this pressure is maintained and
contact your installer or maintenance engineer if there is a permanent
significant drop in pressure indicated on the gauge. If the system loses
pressure it should be re-pressurised as instructed by the installer
(N.B. Maximum pressure 2.5 bar).
CLEARANCES
Your installer will have provided adequate space around the
appliance for safety and servicing. Do not restrict this space by the
addition of cupboards, shelves etc. close to the appliance.
Minimum clearances in millimetres.
ROOM THERMOSTAT
A room thermostat may be fitted for control of the central heating
temperature. It will be located in one room of the home. The method
of setting a room thermostat varies with the type and manufacture.
Refer to the instructions supplied with the room thermostat.
THERMOSTATIC RADIATOR VALVES
If thermostatic radiator valves are to be fitted to the system then
they must conform to the requirements of BS2767:1972. It is advisable
to leave one valve permanently set at maximum to prevent the boiler
short cycling.
GENERAL NOTES
RSF
Left-hand side 10
Right-hand side 10
In Front 600
Above 180
Below 200

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6
SHOWERS, BIDETS, TAPS AND MIXING
VALVES
Standard hot and cold taps and mixing valves used with the
appliance must be suitable for operating at the available mains
pressure. Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a temperature.
Hot and cold mains fed water can be supplied direct to an
overrim flushing bidet subject to local water company requirements.
With all mains fed systems the flow of water from the individual
taps will vary with the number of outlets operated simultaneously
and the cold water mains supply pressure to the property. Flow
balancing using ‘Ball-o-Fix’ type valves is recommended to avoid an
excessive reduction in flow to individual outlets.
For further information contact Worcester Heat Systems Ltd.
HOT AND COLD FLOW
If the flow of water demanded from both hot and cold service
outlets is dependent upon mains supply, it may not be possible in
some installations to operate all outlets simultaneously.
WATER MAINS FAILURE
It is important to note that in the event of a mains water supply
failure, no tap water will be available until the mains supply is
restored.
USE IN HARD WATER AREAS
In temporary hard water areas (more than 350mg/litre or 200ppm
calcium bicarbonate) it is recommended that a proprietary scale
reducer is fitted in the mains cold water connection to the appliance.
Consult the local water company for additional advice.
Installation of a scale inhibitor assembly should be in accordance
with the requirements of the local water company. An isolating valve
should be fitted to allow servicing.
The water hardness can be determined by reference to the local
water company.
DOMESTIC HOT WATER TEMPERATURE
CONTROL
By slightly reducing the flow of domestic water from the tap, the
delivery temperature will be increased. This is of particular advantage
in the winter, for example to increase bath water temperature and to
remove heavy grease deposits on plates, etc. Also this will provide an
added advantage of reducing the delay before hot water is obtained.

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VENTILATION OF THE APPLIANCE
This is a room sealed appliancem, any ventilation openings in a
wall or door must not be obstructed. Do not allow the flue terminal
fitted on the outside wall to become obstructed or damaged.
If the appliance is fitted in a compartment do not use the
compartment for storage purposes unless it conforms to the
requirements of BS 6798:1987: Section 6 and the requirements of
Section 6. Air Supply in the Installation Instructions. It is essential
that the airing space is separated from the boiler space by a perforated
non-combustible partition as described in BS 6798:1987.
NOTE: Do not place anything on top of the appliance.
CIRCULATING PUMP
This may be fitted with a speed adjuster. If so it will be factory
set at maximum and should not be changed.
FROST PRECAUTIONS
Your British Gas Engineer, or any service engineer will advise
you on suitable frost precautions.
For short periods the built-in frost protection of the appliance
will be adequate.
If the appliance is not to be used for a long period of time and
there is a likelihood of freezing, then the appliance should be drained.
SERVICE
Annual servicing is important in order to ensure continuing high
efficiency and long life for your appliance. In the event of any
difficulty in making suitable servicing arrangements, Worcester Heat
Systems Limited, your British Gas Engineer or other competent
persons will discuss regular servicing arrangements and offer a
comprehensive maintenance contract.
IMPORTANT: Do not touch or adjust any sealed component.
WARNING
If a gas leak exists, or is suspected, turn off the gas supply to the
appliance at the service cock and consult your local British Gas
Engineer or service engineer.
Do not touch any electrical switches to turn them either on or off.
Open all windows and doors. Do not smoke. Extinguish all naked lights.
CLEANING
Do not use abrasive cleaners on the outer casing. Use a damp
cloth and a little detergent.

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OPERATION OF
CONTROLS
(See also label on inside of appliance front panel).
The appliance is fitted with the following controls:
CENTRAL HEATING TEMPERATURE
The position of this knob will determine the temperature of the
water delivered to the radiators between the ‘I’ and ‘MAX’ position.
When the knob is turned anti-clockwise past the ‘I’ position towards
the ‘’(Summer Position), then the appliance will operate in the
HOT WATER mode only and no heat will be delivered to the radiators.
FACIA MOUNTED PROGRAMMER (if fitted)
Your installer may have fitted a mechanical programmer into the
facia of your appliance. Operating instructions are supplied with the
programmer.
SYSTEM PRESSURE GAUGE
The red needle has been set to show the sealed system pressure
which is required for the appliance to operate effectively. The grey
needle will show the actual pressure in the system.
INDICATOR LIGHT
Mains electricity indicator:
OFF : No mains electricity to the appliance
ON : Mains electricity is connected to the
appliance
FLASHING : Sensor fault.
OVERHEAT CUT-OFF
THERMOSTAT
The appliance will enter a lockout condition in the event of
overheating.
An overheat cut-off thermostat is fitted to the appliance which
will interrupt the electricity supply to the ignition circuit.
If the overheat cut-off has operated the fan and/or pump will run
but the burner will not light. (No spark generation).
The appliance can be reset by pressing the overheat cut-off
button.

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9
Fig. 2. 24i/28i Controls.
Mains indicator
Central heating temperature
control and on/off knob
System pressure
gauge
Overheat cut-off
button

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10
TO LIGHT THE APPLIANCE
Check that the water valves to the central heating circuit are open.
Check that the grey needle on the pressure gauge is not below
the required pressure.
Switch on the mains electricity. The power on indicator will
light. Set the room thermostat, if fitted, to maximum. Turn the central
heating temperature control knob to ‘MAX’.
The burner will light.
Set the central heating control knob and the room thermostat, if
fitted, to the desired temperature.
Fig. 3. 28i with front panel removed.
Circulating
pump
Front panel
hook
DA A
PLA E
Locating peg
Burner
viewing
window
Gas valve
TO LIGHT AND STOP THE
APPLIANCE

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TO STOP THE APPLIANCE
For Short Periods
Turn the central heating temperature control knob fully anti-
clockwise to the ‘’position. Domestic Hot Water will still be
available as required.
For Long Periods
Switch off the mains electricity.
A facia mounted mechanical programmer will require resetting
once the mains supply has been disconnected.
ELECTRICITY SUPPLY FAILURE
If the electricity supply fails the appliance will not operate. Once
the supply is restored the appliance will return to normal operation. If
a programmer is fitted, check that the settings have been maintained.
IGNITION LOCKOUT
The appliance will enter a lockout condition in the event of the
burner failing to ignite.
If the burner fails to light within a preset time of 10 seconds the
electricity supply to the gas valve will be interrupted.
The appliance can be reset by ending the present demand which
in a central heating demand means turning the central heating
temperature control to ‘’and back to the required setting or ending
the room thermostat/programmer demand.
Re-ignition will be attempted after a delay of four minutes.
Domestic hot water demands do not have this delay.
Check that the gas supply has not been interrupted.
If this condition continues to occur, then call a service engineer.
AIR FLOW DEVICE
The appliance will enter a lockout condition in the event of an
air flow fault.
If the controls fail to detect the correct air flow through the
appliance the electricity supply to the gas valve will be interrupted.
The appliance will try to re-light once the air-flow signal is re-
established. Check that the flue terminal has not been obstructed or
damaged, and that the fan and air pressure switch are in good order.
If this condition continues to occur, then call a service engineer.
REMOVAL AND REPLACEMENT
OF THE FRONT PANEL (See Fig. 3)
Necessary to check if burner is lit.
Removal:
Holding the panel at the edges, slide it upwards to disengage the
clips and ease the top edge forwards and upwards to raise it clear of
the two pegs on the top edge of the facia.
Replacement:
Locate the two holes in the bottom edge of the front panel over
the two pegs on the top edge of the facia and reverse the removal
procedure.
WARNING: Do not touch any component within the appliance
when it is running as some may be very hot.

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12
More than 30% of all calls made to Worcester Heat Systems to
report appliance faults or breakdowns prove to be false alarms, as there
is often a simple explanation for the apparent malfunction.
So, to help you save time and money – not to mention frustration
and inconvenience – please refer to the General Information, Notes and
Lighting Instructions ensuring all controls are set correctly.
If, after following the instructions the appliance still fails to operate
correctly call the Worcester Heat Systems Service Centre. Arrangements
will be made for an engineer to call as soon as possible.
CALL-OUT CHARGES
All of our field service engineers are factory trained.
If you request a visit from an engineer and your appliance has been
installed within the last 12 months, no charge will be made for parts
and/or labour, providing:
•The appliance was commissioned correctly on installation.
•An appliance fault is found and the appliance has been installed
within the past 12 months.
A call-out charge will be made where:
•The appliance has been installed for over 12 months, or
•Our Field Service Engineer finds no fault with the appliance (see
note), or
•The cause of breakdown is with other parts of your
plumbing/heating system, or with equipment not supplied by Worcester.
NOTE: Invoices for attendance and/or repair work carried out on
your appliance by any third party will not be accepted.
APPLIANCE FAILS TO
OPERATE

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13
MAINTAINING YOUR
APPLIANCE
Your new Worcester gas-fired appliance 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, competent servicing
and annual maintenance checks beyond the initial 12 month
guarantee period.
Regular service contracts can be arranged with your installer
– however if you have difficulty making a satisfactory
arrangement simply contact Worcester Heat Systems on
0345 256206 for help.

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14
SERVICE CENTRES
CONTACT NUMBERS:
UK Call Centre Tel. [phone]
UK Call Centre Fax. [phone]
Scotland only Fax. [phone]
OPERATING HOURS:
Mon - Fri 8.00am to 6.00pm
Sat 8.30am to 1.00pm
Please contact our UK Call Centre number where our friendly operators
will book your call with one of our team of nationwide engineers.
NOTE:
Sunday and Bank Holiday cover is not available
IMPORTANT
Do not touch or adjust any sealed component

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15
YOUR WORCESTER
GUARANTEE
This appliance is guaranteed against faulty materials or
workmanship for a period of twelve calendar months from the
date of installation subject to the following conditions and
exceptions.
1. That during the currency of this
guarantee any components of the
unit which are proved to be faulty
or defective in manufacture will be
exchanged or repaired free of
material charges and free of labour
charges by Worcester Heat Systems
Limited.
2. That the householder may be asked
to prove the date of installation,
that the appliance was correctly
commissioned and, where
appropriate, the first 12 month
service has been carried out to the
satisfaction of Worcester Heat
Systems Limited when requested.
3. That any product or part thereof
returned for servicing under the
guarantee must be accompanied by
a claim stating the Model, Serial
Number, Date of Installation.
4. That Worcester Heat Systems
Limited will not accept
responsibility for damage caused by
faulty installation, neglect, misuse
or accidental damage, the non-
observance of the instructions
contained in the installation and
Operating Instructions Leaflets.
5. That the appliance has been used
only for normal domestic purposes
for which it was designed.
6. That this guarantee applies only to
equipment purchased and used in
mainland Great Britain.
This guarantee is given in addition to all your normal statutory rights.

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EXCELLENCE COMES AS STANDARD
Worcester Heat Systems Limited. Cotswold Way, Warndon, Worcester WR4 9SW.
Telephone: [phone]. Fax: [phone].
Technical Service Helpline 08705 266241.
www.worcester-bosch.co.uk 8 716 145 027e 11/00
GUARANTEE
REGISTRATION
You should complete and return the postpaid Guarantee
Registration Card within 14 days of purchase.
The card will register you as the owner of your new
Worcester appliance and, while this will not affect your statutory
rights in any way, it will assist us to maintain an effective and
efficient customer service by establishing a reference and
permanent record for your boiler.
IMPORTANT: SERIAL NUMBER. Copy the number off the
Guarantee Card.
FOR YOUR OWN RECORD
MODEL SERIAL NUMBER
(See identity label inside appliance casing)
TYPE/SIZE DATE OF INSTALLATION