Worcester ZWB 7-25 HE combi User manual

Users Instructions and
Customer Care Guide
Greenstar HE combi Condensing boiler
Greenstar HE system Condensing boiler
6 720 610 577-00.10
ZWB 7-25 HE combi
GC-Number: 47 311 73
ZWB 7-3 HE combi
GC-Number: 47 311 74
ZB 7-28 HE system
GC-Number: 41 311 58
6 720 610 577 GB (03.02) OSW

2
Contents
6 720 610 577 GB (03.02)
Contents
Excellence comes as standard 3
Safety precautions 4
1 General notes 5
2 Controls 9
3 Operating the ppliance 10
3.1 Preparation 10
3.2 Switching the Appliance On/O 12
3.3 Switching on the Central Heating 13
3.4 Controlling Central Heating 13
3.5 Combination Boilers:
Setting the Hot Water Temperature 14
3.6 Summer Mode, Hot Water Only
(Combi Appliances) 15
3.7 Frost protection (Combi Appliances) 15
3.8 Fault Condition 16
4 Tips on saving energy 17
5 General Information 18
6 Maintaining your appliance 19
7 Service centres 19
8 Fault or breakdown 20
9 Your Bosch guarantee 21
10 Guarantee registration 22
11 Operating Instructions Quick Reference 23

3
Excellence comes as standard
6 720 610 577 GB (03.02)
Excellence comes as standard
Than you for purchasing a Worcester Greenstar condensing
appliance.
The Worcester Greenstar Series has been developed by the
Bosch Group and the strictest quality control standards are
demanded throughout every stage of production.
Indeed, the Bosch Group have led the field in innovative appliance
design and performance for many years.
The result is that your new Greenstar 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
2 year parts and labour guarantee.
And it’s bac ed up by Worcester Care Call a complete mainte-
nance scheme to eep your boiler operating at pea condition and
efficiency.
No wonder that more and more people are agreeing that when it
is gas, it has to be a Worcester Condensing appliance.
Benchmark
The “Benchmar ” initiative is the new code of practice to encour-
age the correct installation, commissioning and servicing of
domestic central heating boilers and system equipment.
The “log-boo ” is a vital document that must be completed by the
installer at the time of installation. It confirms that the boiler has
been installed and commissioned according to the manufacturers
instructions.
Without the completion of the “log-boo ”, manufacturers may
refuse to respond to a call–out from a householder, who will be
advised that he or she must call bac the installer, who has not ful-
filled his obligations to record the information required by the ini-
tiative.

4
Safety precautions
6 720 610 577 GB (03.02)
Safety precautions
Gas Safety (Installation and Use) Regulations 1998
It is the law that all gas appliances are installed by a competent
person in accordance with the above regulations. Failure to install
appliances correctly could lead to prosecution. It is in your inter-
est, and that of safety, to ensure compliance with the law.
If you smell gas:
B Turn off gas service coc at the meter.
B Open all doors and windows.
B Do not operate any electrical switches.
B Do not smo e.
B Extinguish any na ed flames.
B Call your gas company.
If you smell fumes from the appliance:
B Switch off appliance.
B Open windows and doors.
B Inform your heating engineer.
Fitting and modifications
B Fitting of the appliance or any modifications to the appliance
may only be carried out by a competent person.
B Flue systems must not be modified in any way.
Maintenance
B We recommend that you ta e out a maintenance contract
with a competent installer and have the appliance serviced at
regular intervals.
B Ensure that your Service Engineer uses only genuine spare
parts!

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General notes
6 720 610 577 GB (03.02)
Combustible materials
B Do not store or use any combustible materials (paper, thin-
ners, paints etc.) in the vicinity of the appliance.
Health and safety
B This appliance contains no asbestos products.
B There is no potential hazard due to the appliance being electri-
cally unsafe.
B There are no substances used in the construction that are a
potential hazard in relation to the COSHH Regulations (Con-
trol of Substances Hazardous to Health Regulations 1988).
Combustion Air/Ambient Air
B Keep combustion air/ambient air free of corrosive substances
(e.g. halogenated hydrocarbons which contain chlorine or flu-
orine compounds). In this way corrosion can be prevented.
1 General notes
To get the best from your appliance please read these instruc-
tions carefully.
Sealed heating systems
The appliance is fitted to a sealed heating system which is pre-
pressurised. Your installer will tell you of the minimum and maxi-
mum pressure which must be indicated on the pressure gauge.
Chec regularly that the pressure is maintained and contact your
installer or maintenance engineer if there is a permanent signifi-
cant drop in the pressure. If the system loses pressure it should
be repressurised and the cause of the fall investigated.
Central heating systems
During the first few hours of operation of the central heating sys-
tem, chec that all radiators are being heated at an even rate. 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. As your installer to show you how this is

6
General notes
6 720 610 577 GB (03.02)
done. 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 lea s be found in the system or excessive venting is
required then a service engineer must be contacted to inspect the
installation and rectify any fault.
Only additives that are compatible with aluminium may be used in
the system. Any incompatible additive used will invalidate the
guarantee.
Condensate drain
This is a condensing appliance and the terminal will, at times, give
out a plume of water vapour. This is quite normal.
The appliance produces quantities of condense which is dis-
charged regularly through the siphon.
Clearances
Your installer will have provided adequate space around the appli-
ance for safety and servicing access. Do not restrict this space
with the addition of cupboards, shelves etc. next to the appliance.
Room thermostat
A room thermostat with volt free contacts (i.e. battery operated)
may be fitted to control the central heating. Refer to the instruc-
tions supplied with the thermostat for information on siting and
setting. A programmable thermostat may also be used with this
appliance to provide additional timed control of the central heat-
ing.
Left-hand side 5 mm
Right-hand side 5 mm
In Front 600 mm
Above Casing (Vertical Flue) 75 mm
Above Flue Turret 30 mm
Below 200 mm
Table 1

7
General notes
6 720 610 577 GB (03.02)
Cylinder thermostat - system boilers
The cylinder thermostat should be set to 60°C which will be sat-
isfactory for bathing/washing in normal circumstances.
Thermostatic radiator valves
It is recommended that this type of valve is fitted to all the radia-
tors except one, usually the bathroom radiator. They should con-
form to the requirements of BS2767:10.
Showers, bidets, taps and mixing valves – Combination
Boilers
Standard hot and cold taps and mixing valves must be suitable for
operating at mains pressure. Thermostatically controlled or pres-
sure equalising shower valves will guard against the flow of water
at too high a temperature.
Hot and cold mains fed water can be supplied directly to an over-
rim flushing bidet subject to local water company requirements.
With all mains fed systems the flow of water from 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 Techni-
cal Services Department.
Hot and cold flow – Combination Boilers
The flow of water demanded from both hot and cold service out-
lets is dependent upon the mains supply, it may not be possible
in some installations to operate all outlets simultaneously.
Water mains failure – Combination Boilers
If there is a failure of the mains water supply then no water will be
available at a tap or shower until the mains supply is restored. The
appliance will still operate in the central heating mode.

8
General notes
6 720 610 577 GB (03.02)
Use in hard water areas – Combination Boilers
In exceptionally hard water areas a device to prevent scale forma-
tion may be fitted. Installation of a scale inhibitor assembly should
be in accordance with the requirements of the local water com-
pany. An isolating valve should be fitted to allow for servicing.
Alternatively the maximum temperature of the domestic hot water
may be reset to about 45 °C which will reduce the ris of scale
formation in these hard water areas.
Ventilation
This is a room sealed appliance and does not require any air for
combustion from inside the house. If the appliance is fitted into a
cupboard or a compartment is built around the appliance after
installation then the compartment must be separated from the
boiler space by a perforated non-combustible partition as
described in BS6798.
Notwithstanding the requirements of BS6798, there is no need
for ventilation openings to be provided in the compartment
because of the low heat loss from the casing.
Do not allow the flue terminal fitted on the outside wall to become
obstructed or damaged.
Pump
The pump will have been set by the manufacturer and must not be
manually re-adjusted.

9
Controls
6 720 610 577 GB (03.02)
2 Controls
8.1 System Pressure gauge
61 Reset button
135 Master switch
136 Central heating temperature control
17 Service valves in CH flow and return
171 Hot water
172 Gas isolation valve (open)
173 Cold water inlet
295 Identification stic er
31 Hot water temperature control (combi)
317 Display
363 Indicator lamp for “burner on”
364 Indicator lamp for “off/on”
365 “Chimney sweep” button
366 Service button
367 “ECO” button
365 61 317 366 367
ECO
310
364
135
295
136
170
363
172 170
173
6 720 610 577-01.1O
8.1
E
171

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Operating the ppliance
6 720 610 577 GB (03.02)
3 Operating the Appliance
3.1 Preparation
Turn on the gas cock (172).
BPress in the handle and turn it anti-cloc wise as far as the stop
(when handle is in line with direction of flow, the coc is open).
Central heating system valves (17 )
BUsing a spanner, turn square nut until groove is in line with
direction of flow (see detail).
Groove at right angles to direction of flow = off.
Cold water inlet valve (173)
BTurn handle so that it is in line with direction of flow.
When handle is at right angles to direction of flow, the valve is
closed.
170
172 173
6 720 610 577-02.1O

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Operating the ppliance
6 720 610 577 GB (03.02)
Check the central heating system pressure
BThe pointer on the pressure gauge (8.1) should be about
1 bar.
BIf the pointer is below 1 bar (when the system is cold), top up
the system with water until the pointer is 1 bar. Your installer
will have shown you how to do this.
BThe maximum operating pressure of 2.5 bar at maximum
central heating flow temperature must not be exceeded. If the
pressure increases to 3 bar then the relief valve (15) opens.
8.1
15
6 720 610 577-03.1O
bar
0
1
23
4

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Operating the ppliance
6 720 610 577 GB (03.02)
3.2 Switching the Appliance On/Off
Switching on
BSwitch on the appliance at the master switch (I).
The indicator lamp shows green and the display will show the
central heating flow temperature, when the appliance is oper-
ating in the central heating mode.
The trap filling programme ensures that the condensation trap is
filled after the appliance has been installed or after the appliance
has been out of use for a long period. For that reason, the appli-
ance remains at minimum heating output for 15 minutes.
Switching off
BSwitch off the appliance at the master switch ( ).
The green indicator lamp goes out. The optional timer will con-
tinue running until the emergency supply is exhausted.
iIf the display alternates between -II- and the cen-
tral heating flow temperature, the trap filling pro-
gramme is active.
6 720 610 333-04.1O

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Operating the ppliance
6 720 610 577 GB (03.02)
3.3 Switching on the Central Heating
BTurn the central heating temperature control to the desired
level:
–“Min” setting: 35˚C
–Low-temperature heating: setting “E” (approx. 75˚C)
–“Max” setting: 88˚C
When the burner is lit, the red indicator lamp is illuminated.
3.4 Controlling Central Heating
BSet the timer to the correct time.
BSet room thermostat to the desired room temperature.
BSet temperature driven control unit, if fitted. Refer to the
instructions with the control.
BSet the thermostatic radiator valves to the desired settings.
6 720 610 333-05.1O

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Operating the ppliance
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3.5 Combination Boilers: Setting the Hot
Water Temperature
Hot water temperature
On combi models, the hot water temperature can be set to
between approx. 40˚C and 60˚C using the temperature
control .
The domestic hot water temperature is not shown on the display.
“ECO” button
By pressing and holding the “ECO” button , until the display
lights, you can switch between Comfort mode and Economy
mode.
Comfort mode: button is not lit (factory setting)
The appliance is held constantly at the set temperature. This
means that hot water is available almost instantaneously at the
tap. Consequently the appliance will switch on at intervals, even if
no hot water is being drawn.
Control Setting Water Temperature
Anti-cloc wise limit approx. 40˚C
approx. 55˚C
Cloc wise limit approx. 60˚C
Table 2
6 720 610 333-07.1O

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Operating the ppliance
6 720 610 577 GB (03.02)
ECO mode with demand detection, button is lit
The demand detection function enables maximum gas and water
economy.
Briefly turning a hot water tap on and then off again signals
demand to the appliance which then heats up the water to the set
temperature.
Hot water is thus available in about 1 minute.
ECO mode, button is lit
Water is not heated up until hot water is drawn. This means that
there is a longer waiting period before hot water is available.
3.6 Summer Mode, Hot Water Only
(Combi Appliances)
With room thermostat
BTurn temperature control on the appliance anti-cloc wise
as far as the stop.
The central heating is now turned off. The hot water function
and the mains power supply for the heating programmer and
timer remain switched on.
3.7 Frost protection (Combi Appliances)
BLeave master switch switched on.
If the appliance is to be left for long periods switch the central
heating off:
BAdd an anti-freeze liquid that is compatible with aluminium to
the water in the central heating system.
Suitable products are available from Betz-Dearborn Tel.: 0151
4209563 and Fernox Tel.: [phone].

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Operating the ppliance
6 720 610 577 GB (03.02)
3.8 Fault Condition
In the unli ely event of a fault occuring while the appliance is in
operation:
The display then shows a fault code and the button may also
flash.
If the button flashes:
BPress and hold the button until the display shows “– –”.
The appliance will then start up again and the display will show
the central heating flow temperature.
If the button does not flash:
BSwitch the appliance off and then on again at the master
switch.
The appliance will start up again and the central heating flow
temperature will be displayed.
If the fault remains and can not be cleared:
BCall your approved installer or Greenstar Customer Service for
assistance, giving a description of the fault and, if possible, the
fault code from the facia display.

17
Tips on saving energy
6 720 610 577 GB (03.02)
4 Tips on saving energy
Heating economically
The boiler is designed to provide a high level of comfort while
eeping 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 tech-
nical term for this process is modulating control. Modulating con-
trol eeps temperature fluctuations small 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 an appliance that continually switches on and off.
Central heating systems with room thermostats/thermo-
static radiator valves
The central heating control on the boiler should be set to the max-
imum rated temperature of the central heating system or to posi-
tion “E”, when the maximum central heating water temperature
obtained is 75˚C.
The temperature can be set individually in each room (except pri-
mary room with the room thermostat) using the thermostatic radi-
ator valves. If you wish to have a lower temperature in the primary
room than in the other rooms, leave the room thermostat at the set
temperature and turn down the radiator using the radiator valve.
Reduced-output operation
Considerable fuel savings can be made by slightly reducing the
room temperature. Lowering the temperature by 1°C can bring
about energy savings of up to 5 %. However, it is not advisable to
allow any room temperature to fall below +15°C. The room tem-
perature for reduced-output mode can be set separately on the
room thermostat. Instructions are given in the control unit operat-
ing instructions.

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General Information
6 720 610 577 GB (03.02)
Hot water
A lower setting on the hot water temperature control can result in
considerable energy savings.
For combi appliances:
The on-demand activation using the ECO-button ma es possi-
ble the maximum savings of gas and water.
Now you now how to heat your home economically with the
Greenstar gas condensing boiler. If you have any other questions,
please contact your installer – or write to us.
5 General Information
Cleaning the Outer Case
Wipe down the outer case with a damp cloth. Do not use abrasive
or caustic cleaning agents.
Appliance details
If you ever need to call Greenstar Customer Service it helps us a
great deal if you can provide precise details of your appliance.
The information is printed on the appliance identification plate/
stic er (see page 9, item 295).
Your installer will have completed the Benchmar “log-boo ”
giving details of the boiler together with name, address and regis-
tration number. Have the “log-boo ” to hand when calling a
Service Engineer.

19
Maintaining your appliance
6 720 610 577 GB (03.02)
6 Maintaining your appliance
Your new Worcester Greenstar gas-fired appliance represents a
long-term investment in a reliable, high quality product.
In order to realise its maximum wor ing life, and to ensure it con-
tinues to operate at pea efficiency and performance, it is essen-
tial that your boiler receives regular, competent servicing and
maintenance chec s beyond the initial 2 year guarantee period.
Regular service contracts can be arranged with your installer –
however if you have difficulty ma ing a satisfactory arrangement
simply contact Worcester Heat Systems on 08705 256206 for
help.
If you would li e to now more about Worcester’s extended war-
ranty options please tic the appropriate box on your warranty reg-
istration card.
7 Service centres
We have Service Centres situated throughout the country.
If you have a service request simply call our local rate
number above and your request will be routed to your
Regional Service Centre.
Region Telephone Fax
Operating
Hours
(Mon-Fr)
Operating
Hours
(Sat)
Sc
Scotland
87 5
2562 6
(01506)
441687
8.00 am
TO
6.00 pm
8.30 am
TO
1.00 pm
NW
North West [phone]
E Eastern
W Western (01905)
757536
SE South
SW South
Table 3

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Fault or breakdown
6 720 610 577 GB (03.02)
8 Fault or breakdown
This product is supported in the UK by Worcester Heat Systems
Ltd. – part of the Bosch Group.
A specialist factory trained field SERVICE ENGINEER is available
to attend a brea down or manufacturing fault occuring on this
appliance.
No charge will be made for parts and/or labour providing:
•An appliance fault is found and the appliance has been
installed within the past 24 months. Reasonable evidence of
this must be supplied on request.
•2nd year warranty is dependent on annual servicing.
A call-out charge will be made where:
•The appliance has been installed for over 24 months.
OR
•Our Field Service Engineer finds no fault with the appliance
(see NOTE).
OR
•The cause of brea down is misuse or with other parts of your
plumbing/heating system, or with equipment not supplied by
Worcester.
NOTE: No appliance fault is found on over 30 % of all service call
outs.
If in doubt contact our Technical Helpline on 08705 266241.
IN THE EVENT OF AN APPLIANCE FAULT OR BREAK-
DOWN please contact your Service Centre (see over). Your serv-
ice administrator will arrange for an engineer to call with the
minimum of delay; under normal circumstances this will be within
the period 1-3 wor ing days (excluding wee ends) for priority
brea down situations (no hot water and/or heating service).
INVOICES FOR ATTENDANCE AND REPAIR WORK CAR-
RIED OUT ON THIS APPLIANCE BY ANY THIRD PARTY
WILL NOT BE ACCEPTED.