Worcester ZWB 7-27 HE 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 7-27 HE combi
GC-Number: 47 311 55
ZB 7-27 HE system
GC-Number: 41 311 49
6 720 610 577 GB (01.07) OSW

2
Contents
6 720 610 577 GB (01.07)
Contents
Excellence comes as standard 3
Safety precautions 4
1 General notes 6
2 Controls 9
3 Operating the Appliance 10
3.1 Preparation 10
3.2 Switching the Appliance On/Off 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 19
6 Maintaining your appliance 19
7 Service centres 20
8 Fault or breakdown 21
9 Your Bosch Greenstar guarantee 22
10 Guarantee registration 23
11 Operating Instructions Quick Reference 24

3
Excellence comes as standard
6 720 610 577 GB (01.07)
Excellence comes as standard
Thank 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 appli-
ance 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 backed up by Worcester Care Call a complete mainte-
nance 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 Condensing appliance.
Benchmark
The “Benchmark” 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-book” 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-book”, manufacturers may
refuse to respond to a call–out from a householder, who will be
advised that he or she must call back 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 (01.07)
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:
y
Turn off gas service cock at the meter.
y
Open all doors and windows.
y
Do not operate any electrical switches.
y
Do not smoke.
y Extinguish any naked flames.
y
Call your gas company.
If you smell fumes from the appliance:
y
Switch off appliance.
y
Open windows and doors.
y
Inform your heating engineer.
Fitting and modifications
y
Fitting of the appliance or any modifications to the appliance
may only be carried out by a competent person.
y
Flue systems must not be modified in any way.
Maintenance
y
We
recommend that you take out a maintenance contract
with a competent installer and have the appliance serviced at
regular intervals.
y
Ensure that your Service Engineer uses only genuine spare
parts!

5
Safety precautions
6 720 610 577 GB (01.07)
Combustible materials
y
Do not store or use any combustible materials (paper, thin-
ners, paints etc.) in the vicinity of the appliance.
Health and safety
y
This appliance contains no asbestos products.
y
There is no potential hazard due to the appliance being electri-
cally unsafe.
y
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
y
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.

6
General notes
6 720 610 577 GB (01.07)
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.
Check 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, check 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. Ask your installer to show you how this is
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 leaks 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.

7
General notes
6 720 610 577 GB (01.07)
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 instructions
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 heating.
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.
Left-hand side 5 mm
Right-hand side 5 mm
In Front 600 mm
Above Casing (Vert. Flue) 75 mm
Above Flue Turret 30 mm
Below 250 mm
Table 1

8
General notes
6 720 610 577 GB (01.07)
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.
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 risk 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 BS6798:87.
Notwithstanding the requirements of BS6798:87, 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 (01.07)
2 Controls
8.1 System Pressure gauge
61 Reset button
135 Master switch
136 Central heating temperature control
170 Service valves in CH flow and return
171 Hot water
172 Gas isolation valve (open)
173 Cold water inlet
295 Identification sticker
310 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

10
Operating the Appliance
6 720 610 577 GB (01.07)
3 Operating the Appliance
3.1 Preparation
Turn on the gas cock (172).
yPress in the handle and turn it anti-clockwise as far as the stop
(when handle is in line with direction of flow, the cock is open).
Central heating system valves (170)
yUsing 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)
yTurn 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

11
Operating the Appliance
6 720 610 577 GB (01.07)
Check the central heating system pressure
yThe pointer on the pressure gauge (8.1) should be about
1 bar.
yIf 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.
yThe 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
123
4

12
Operating the Appliance
6 720 610 577 GB (01.07)
3.2 Switching the Appliance On/Off
Switching on
ySwitch 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
ySwitch off the appliance at the master switch (0).
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

13
Operating the Appliance
6 720 610 577 GB (01.07)
3.3 Switching on the Central Heating
yTurn 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
ySet room thermostat to the desired room temperature.
ySet outside- temperature driven control unit, if fitted. Refer to
the instructions with the control.
ySet the thermostatic radiator valves to the desired settings.
6 720 610 333-05.1O

14
Operating the Appliance
6 720 610 577 GB (01.07)
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-clockwise limit approx. 40 °C
lapprox. 55 °C
Clockwise limit approx. 60 °C
Table 2
6 720 610 333-07.1O

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Operating the Appliance
6 720 610 577 GB (01.07)
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
yTurn temperature control on the appliance anti-clockwise
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)
yLeave master switch switched on.
If the appliance is to be left for long periods switch the central
heating off:
yAdd a suitable anti-freeze fluid to the water in the central heat-
ing system.
Suitable products are available from Betz-Dearborn Tel.: 0151
4209563 and Fernox Tel.: [phone].

16
Operating the Appliance
6 720 610 577 GB (01.07)
3.8 Fault Condition
In the unlikely 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:
yPress 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:
ySwitch 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:
yCall 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 (01.07)
4 Tips on saving energy
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 con-trolled
according to the level of demand for heat. The boiler con-tinues 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 keeps 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 the 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.

18
Tips on saving energy
6 720 610 577 GB (01.07)
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 makes possi-
ble the maximum savings of gas and water.
Now you know 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.

19
General Information
6 720 610 577 GB (01.07)
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/
sticker (see page 9, item 295).
Your installer will have completed the Benchmark “log-book”
giving details of the boiler together with name, address and regis-
tration number. Have the “log-book” to hand when calling a
Service Engineer.
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 working life, and to ensure it con-
tinues to operate at peak efficiency and performance, it is essen-
tial that your boiler receives regular, competent servicing and
maintenance checks beyond the initial 2 year 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 08705 256206 for
help.
If you would like to know more about Worcester’s extended war-
ranty options please tick the appropriate box on your warranty reg-
istration card.

20
Service centres
6 720 610 577 GB (01.07)
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
08705
256206
(01506)
441687
8.00 am
TO
6.00 pm
8.30 am
TO
1.00 pm
NW
North West (01625)
614308
E Eastern
W Western (01905)
757536
SE South
SW South
Table 3