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