Worcester OIL HEATSLAVE 12/14 User guide

OIL HEATSLAVE
12/14 15/19 20/25 26/32
CONVENTIONAL FLUE AND ROOM SEALED BF FLOOR
STANDING COMBINATION BOILER FOR CENTRAL
HEATING AND MAINS FED DOMESTIC HOT WATER
INSTALLATION AND
SERVICING INSTRUCTIONS
BOILER OUTPUT
Domestic Hot Water and Central Heating
12/14 MINIMUM 12 kW (41,000 Btu/h)
MAXIMUM 14 kW (48,000 Btu/h)
15/19 MINIMUM 15 kW (51,000 Btu/h)
MAXIMUM 19 kW (65,000 Btu/h)
20/25 MINIMUM 20 kW (68,000 Btu/h)
MAXIMUM 25 kW (85,000 Btu/h)
26/ 2 MINIMUM 26 kW (8 ,000 Btu/h)
MAXIMUM 2 kW (10 ,000 Btu/h)
THESE INSTRUCTIONS APPLY TO UK MODELS ONLY
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE APPLIANCE

2
1. Installation Regulations...........................................Page 2
2. General Information .................................................Page 2
. Technical Data...........................................................Page 4
4. Siting the Appliance.................................................Page 6
5. Removal of the Cabinet............................................Page 6
6. Air Supply..................................................................Page 11
7. Flue ............................................................................Page 11
8. Oil Supply..................................................................Page 15
9. System Considerations ............................................Page 17
10. Sealed Primary System............................................Page 18
11. Open Vent Primary System.....................................Page 19
12. Domestic Hot Water .................................................Page 20
1 . Electrical....................................................................Page 21
14. Functional Flow Charts............................................Page 24
15. Installation ................................................................Page 27
16. Commissioning .........................................................Page 28
17. Users Instructions ....................................................Page 0
18. Routine Cleaning and Inspection............................Page 0
19. Replacement of Parts...............................................Page 4
20. Short Parts List..........................................................Page 7
21. Fault Finding.............................................................Page 8
Contents
1.1 General installation information and advice may be
obtained from the Oil Firing Technical Association for the
Petroleum Industry (OFTEC). Training courses are also offered by
OFTEC, leading to inclusion on their list of registered engineers.
1.2 The appliance should be installed by a competent person.
The person installing the appliance should be aware of the
Health and Safety at Work Act and take appropriate action to
ensure that the regulations are adhered to. In order to give
optimum efficiency and trouble free operation the appliance
should be commissioned by a qualified engineer. OFTEC
recommends the use of registered engineers for the
commissioning of oil-fired burners.
1. The manufacturers notes must not be taken, in anyway, as
overriding statutory obligations.
1.4 The compliance with a British Standard does not, of itself,
confer immunity from legal obligations.
In particular the installation of this appliance must be in
accordance with the relevant requirements of the following
British Standards and regulations in respect of the safe
installation of equipment.
BS 5410: part 1: Code of practice for Oil Fired Boilers.
BS 7 : part 5: Specification for Oil Storage Tanks.
BS 75 3: Code of Practice for treatment of water in domestic hot
water central heating systems.
BS 544 : part 1& 2: Code of practice for Forced Circulation Hot
Water and Central Heating for Domestic Premises.
BS 5 55: part 8: Specification for the installation of
thermoplastic pipes and associated fittings for use in domestic
hot and cold water services and heating systems.
BS 72 1: Thermoplastic pipes and associated fittings for hot and
cold water for domestic purposes and heating installations in
buildings.
BS 7074: part 1: Application, selection and installation of
expansion vessels and ancillary equipment for sealed water
systems.
BS 7671: IEE Wiring Regulations, current edition.
The Building Regulations Part J and Part L 1 England and Wales;
Part F Section III and Part J Scotland; Part L and Part F Northern
Ireland.
Local water company bye-laws.
The Control of Pollution (Oil) Regulations.
1.5 To ensure that the installation will perform to the highest
standards, the system and components should conform to
those mentioned in the instructions.
The Benchmark initiative is the new code of practice to
encourage 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 fulfilled his
obligations to record the information required by the initiative.
It is important that:
The services and the system are properly flushed as specified.
The User is clearly instructed on the correct operation of the
appliance.
The benefits of regular servicing are explained - to maintain the
efficiency and extend the life of the appliance.
2.1 These instructions cover both conventional flue (CF)/low
level discharge (LLD) and room sealed balance flue (RS)
appliances.
2.2 The Worcester Oil Heatslave range of appliances covered in
these instructions have been designed to serve domestic central
heating and mains pressure domestic hot water requirements,
ranging from 12 kW to 32 kW.
2. The RS balanced flue appliance forms a fully room sealed
system by surrounding the burner with a unique, fully sealed,
push fit box. This causes the combustion air to be drawn
through a factory sealed air duct formed at the rear and
underside of the boiler. The sealed burner gives excellent
acoustic noise reduction and alleviates the need for an air brick
to be located in the boiler room.
Because the balanced flue system does not rely on the cabinet
panels to form the room seal, combustion readings can be taken
from the flue outlet plate as on a conventional appliance , and
the cabinet panels can be easily removed during installation
thereby preventing any damage.
2.4 The boiler is factory set to the mid range output and can be
altered, if necessary, by adjusting the burner as specified in
tables 2 to 6. The low level discharge and room sealed models
are only suitable for use with 28 second Kerosene heating oil.
NOTE: It is a mandatory requirement of the building
regulations that only 28 second kerosene is used on low
level discharge flues.
2.5 The conventional flue 15/1 , 20/25 and 26/32 models
may be converted to burn 35 second gas oil by changing the
nozzle and burner setting as specified in Tables 3, 4 and 5.
2.6 A colour co-ordinated twin channel programmer can be
fitted to the facia panel. This is available from Worcester Heat
Systems as an optional extra.
2.7 Principle appliance components. See Fig , 4, 5 and 6.
Oil Fired Burner
A fully automatic oil fired pressure jet burner is used to supply
2. General Information1. Installation Regulations

heat to the boiler. The burner can be set to the output
requirements as detailed in Tables 2 to 6.
Heatslave Tank
The Heatslave tank is a heatbank containing 46 litres (10
gallons) of primary hot water. The tank temperature is
controlled by the Domestic Hot water Control Thermostat and is
variable between 55°C and 80°C.
Domestic Hot Water Heat Exchanger
A Water to Water heat exchanger is located on top of the
Heatslave tank. Primary water is pumped from the Heatslave tank
to the heat exchanger whenever there is a flow of domestic water
through a hot water tap. The domestic water thereby extracts the
heat from the heatbank giving mains pressure domestic hot
water. The domestic hot water temperature can be increased by
reducing the water flow rate at the tap and/or adjusting the
Domestic Hot Water Control Thermostat to a higher setting.
Diverter Valve
A motorised diverter valve is located on the pump outlet. The
valve is normally closed to the primary circuit and is powered
open when there is a demand for central heating at a room
thermostat or a demand for heat via the Central Heating Control
Thermostat.
Pump
An integral circulating pump is incorporated within the
appliance casing. This serves the functions of both the central
heating circuit and the Heatslave tank. The pump is factory set
to Setting 3. This should not be adjusted, since this would impair
the domestic hot water performance.
Flow Switch
The domestic mains water inlet is connected to a flow switch
which detects when a domestic hot water tap has been opened.
This activates the burner and pump when the Domestic Hot
Water mode or the Central Heating and Domestic Hot Water
mode is selected. If the Facia mounted operating switch or
programmer (if fitted) is set to OFF or set to Heating On only,
then only the pump will be activated.
Pump Overrun
A pump overrun facility has been incorporated into the control
board which allows excess heat to be dissipated to the hot
water circuit when there is a demand for central heating via the
user operating switch (or programmer where fitted) or to the
Heatslave tank. This prevents the possibility of the boiler
overheating.
Expansion Vessel
A 12 litre expansion vessel is included within the appliance
cabinet.
Manual Reset Overheat Thermostat. See Figs. 3, 4, 5 and 6.
An overheat thermostat is located on the underside of the
electrical panel and is accessible by removing the cabinet front
panel. If a boiler overheat condition arises, the burner will
remain inoperative until the thermostat button is reset.
2.8 OPERATION
The appliance is supplied with a facia mounted operating switch
to allow the selection of hot water in the upper position or
central heating and hot water in the lower position.
Central Heating and Domestic Hot Water Mode
The appliance will supply heat to the central heating system as
required. The water supplied to the central heating circuit can be
set to the desired temperature by adjusting the Central Heating
Control thermostat.
The Heatslave tank will maintain the temperature set on the
Domestic Hot Water Control Thermostat. Demand by the
Domestic Hot Water Control Thermostat or a demand for hot
water at a tap or shower will override the central heating
requirement for the period of the demand. This will generally
have no significant effect on the average room temperature.
When the dwelling and boiler are to be heated from cold,
heating can be achieved more rapidly by turning the Domestic
Hot Water Control Thermostat fully anti-clockwise for the
duration of the warm up period. This will prevent the Heatslave
tank taking priority for the tank warm up period of
approximately 20 minutes.
Domestic Hot Water Mode
The Heatslave tank will maintain the temperature set on the
Domestic Hot Water Control Thermostat.
Central Heating Mode
This mode only applies where a two channel programmer has
been fitted to the system
The appliance will operate as a conventional oil fired boiler. The
water supplied to the central heating circuit can be set to the
desired temperature by adjusting the Central Heating Control
Thermostat.
A demand for domestic hot water at a tap or shower will
override the central heating requirement for the period of
domestic hot water demand. This will allow any residual heat in
the Heatslave tank to be utilised for domestic hot water
purposes.
NOTE: If the Heatslave tank is cold, then no domestic hot water
will be obtained from the system.
Off mode
The central heating system will remain off unless there is a
demand via the frost thermostat (when fitted), whereby the frost
thermostat will activate the pump and burner until the demand
is satisfied.
The burner will remain inoperative in all other circumstances.
If a demand for domestic hot water is made at a tap or shower,
primary water will be pumped from the Heatslave tank through
the domestic hot water heat exchanger. This will provide a
limited output of domestic hot water depending on the amount
of heat stored in the Heatslave tank.
This function will be found useful during periods where it would
be considered undesirable or uneconomical to keep the
Heatslave tank constantly hot, but where there may be a
demand for small quantities of domestic water for hand
washing etc. This would include overnight periods and any
periods of very low domestic hot water demand (eg during the
summer months). In these circumstances the Heatslave tank
can be charged up to maximum temperature once or twice a
day as required using the programmer in the Domestic Hot
Water mode and with the Domestic Hot Water Control
Thermostat set to maximum.

4
3. Technical Data
26/ 2
230V 50 Hz
IP 20
28mm
11
/
4 " BSP
15mm
22mm
11
/
4 " BSP
11
/
4 " BSP
10mm Compression
125mm (5in.)
Balanced Flue Kit (Sec. 7.3)
Below 100°C
76.1 litres (16.7 gal.)
30 m ( 8 ft.)
1 m (3.3 ft.)
1 0Kg (418lbs)
1 7Kg (434lbs)
855mm (33.7in)
670mm (26.4in)
600mm (23.6in)
Electro Oil Sterling 40
120 mbar
40 mbar
57 kg/hr
82.5%
Unrestricted
22 litres/min
(4.8 gallons/min.)
recommended
Not Required
40°C
at 22 litres/min.
1.5 bar
at 22 litres/min.
SPECIFICATIONS
Model 12/14 15/19 20/25
POWER SUPPLY 230V 50 Hz 230V 50 Hz 230V 50 Hz
IP RATING IP 20 IP 20 IP 20
HEATING FLOW 22mm 22mm 22mm
HEATING RETURN 1in. BSP 1in. BSP 1in. BSP
COLD WATER MAINS INLET 15mm 15mm 15mm
DOMESTIC HOT WATER OUTLET 22mm 22mm 22mm
CENTRAL HEATING VENT 1in. BSP 1in. BSP 1in. BSP
CENTRAL HEATING MAKE-UP 1in. BSP 1in. BSP 1in. BSP
FUEL LINE 10mm Compression 10mm Compression 10mm Compression
FLUE REQUIREMENT CF 100mm (4in.) 100mm (4in.) 100mm (4in.)
RS
Balanced Flue Kit (Sec. 7.3) Balanced Flue Kit (Sec. 7.3) Balanced Flue Kit (Sec. 7.3)
HEARTH TEMPERATURE Below 100°C Below 100°C Below 100°C
PRIMARY WATER CAPACITY (TOTAL) 67 litres (14.7 gal.) 67 litres (14.7 gal.) 70.5 litres (15.57 gal.)
MAXIMUM STATIC HEAD 30 m ( 8 ft.) 30 m ( 8 ft.) 30 m ( 8 ft.)
MINIMUM STATIC HEAD 1 m (3.3 ft.) 1 m (3.3 ft.) 1 m (3.3 ft.)
WEIGHT CF 130Kg (286lbs) 133Kg (2 3lbs) 145Kg (31 lbs)
RS 134Kg (2 5lbs)
137 Kg (302lbs) 14 Kg (328lbs)
OVERALL APPLIANCE HEIGHT 855mm (33.7in) 855mm (33.7in) 855mm (33.7in)
OVERALL APPLIANCE WIDTH 520mm (20.5in) 520mm (20.5in) 520mm (20.5in)
OVERALL APPLIANCE DEPTH 600mm (23.6in) 600mm (23.6in) 600mm (23.6in)
BURNER Electro Oil Inter B A Electro Oil Inter B B Electro Oil Inter B11C
WATER SIDE RESISTANCE 10°C Difference 7 mbar 8 mbar 18 mbar
WATER SIDE RESISTANCE 20°C Difference 3 mbar 6 mbar 12 mbar
EXIT FLUE GAS MASS FLOW 24 kg/hr 35 kg/hr 43 kg/hr
SEDBUK RATING* ( SEDBUK BAND C ) 82.5% 82.8% 82.5%
MAXIMUM DOMESTIC HOT WATER FLOW RATE 15 litres/min. 15 litres/min. Unrestricted
(+ or - 15%) (+ or - 15%) 17 litres/min.
(3.3 gallons/min.) (3.3 gallons/min.) (3.7 gallons/min.)
recommended
FLOW RESTRICTOR Lime Green Lime Green Not Required
MAX. DOMESTIC HOT WATER TEMPERATURE RISE 37°C 40°C 40°C
FOR 0 litres (20 gallons) DRAW OFF at 15 litres/min. at 15 litres/min. at 17 litres/min.
MIN. INLET DOMESTIC WATER PRESSURE (DYNAMIC) 1.6 bar 1.6 bar 1.0 bar
FOR MAXIMUM HOT WATER FLOW at 17 litres/min.
CENTRAL HEATING CONTROL THERMOSTAT RANGE 55°C minimum Cut In to 82°C maximum Cut Out
DOMESTIC HOT WATER CONTROL THERMOSTAT RANGE 55°C minimum Cut In to 80°C maximum Cut Out
CENTRAL HEATING AND DOMESTIC HOT WATER
CONTROL THERMOSTAT DIFFERENTIAL 5°C
BOILER HIGH LIMIT THERMOSTAT SET POINT 5 ± 2°C
MANUAL RESET OVERHEAT THERMOSTAT 110 +0–6 °C Cut-out
Table 1
* The value is used in the UK Government Standard Assesment Procedure (SAP) for energy ratings for dwellings.

5
* NOTE: For use on conventional flue only.
** NOTE: The flue gas temperature is measured in the gas sampling hole on the flue outlet plate. The probe should be inserted to a depth of 50mm and angled towards the flue outlet.
The temperature measured is not an absolute flue gas temperature and is for general guidance purposes only!
NOTE: The pump pressure given is for general guidance only as variations in nozzle output can be up to ± 15%. It is, therefore, essential that the air is adjusted to give the correct CO2
value.
NOTE: The nozzle type used on 28 Sec. Kerosene outputs are nozzles calibrated specifically for use with 28 Sec. Kerosene which gives less variation in nozzle output than the standard
35 Sec. Gas Oil nozzles. However, if a 28 Sec. Kerosene nozzle is not available at servicing or commissioning it is appropriate to install a 35 Sec. Gas Oil nozzle providing the output, spray
angle and pattern of the nozzle is the same as the 28 Sec. Kerosene nozzle (e.g. 0.7580°EH may be replaced with a 0.7580°H).
28 Sec. Kerosene 0.40 60°ES 130 1.11 1.41 180 10 6 13.5 46,000 12 41,000
28 Sec. Kerosene 0.50 60°ES 100 1.30 1.64 1 5 11.5 7 15.5 53,000 14 48,000
NOMINAL BOILER RATING AT NORMAL OPERATING TEMPERATURE
12/14 Table 2. Electro Oil Inter B9A Burner (See Fig. 23)
Fuel Nozzle
Pump
Pressure
(p.s.i.)
Fuel Flow
Rate Flue Gas
Temp.
(°C)** %CO2
Approx.
Air
Setting
Appliance
Input
kW Btu/hr kW Btu/hr
Output
Kg/h l/h
28 Sec. Kerosene 0.50 60°ES 110 1.40 1.77 215 10.5 8.5 17 58,000 15 51,000
28 Sec. Kerosene 0.55 80°EH 115 1.5 2.01 225 10.5 8.75 1 65,000 17 58,000
28 Sec. Kerosene 0.60 60°ES 105 1.78 2.25 235 11.5 .0 21.5 73,000 1 65,000
35 Sec. Gas Oil* 0.50 80°S 155 1.80 2.12 235 11.5 .0 21.5 73,000 1 65,000
NOMINAL BOILER RATING AT NORMAL OPERATING TEMPERATURE
15/19 Table . Electro Oil Inter B9B Burner (See Fig. 24)
Fuel Nozzle
Pump
Pressure
(p.s.i.)
Fuel Flow
Rate Flue Gas
Temp.
(°C)** %CO2
Approx.
Air
Setting
Appliance
Input
kW Btu/hr kW Btu/hr
Output
Kg/h l/h
28 Sec. Kerosene 0.60 80°EH 130 1.87 2.37 1 0 11.0-11.5 5.5 22.5 77,000 20 68,000
28 Sec. Kerosene 0.75 80°EH 105 2.10 2.66 205 11.5-12.0 6.0 25 86,000 22.5 77,000
28 Sec. Kerosene 0.75 80°EH 130 2.34 2. 6 220 12.0-12.5 6.5 28 6,000 25 85,000
35 Sec. Gas Oil* 0.60 80°S 120 2.13 2.51 205 11.5-12.0 6.0 25 86,000 22.5 77,000
35 Sec. Gas Oil* 0.60 80°S 150 2.37 2.7 220 12.0-12.5 6.5 28 6,000 25 85,000
NOMINAL BOILER RATING AT NORMAL OPERATING TEMPERATURE
20/25 Table 4. Electro Oil Inter B11C Burner (See Fig. 25)
Fuel Nozzle
Pump
Pressure
(p.s.i.)
Fuel Flow
Rate Flue Gas
Temp.
(°C)** %CO2
Approx.
Air
Setting
Appliance
Input
kW Btu/hr kW Btu/hr
Output
Kg/h l/h
28 Sec. Kerosene 0.85 80°EH 110 2.36 2. 225 11.0-11.5 11 28.5 7,000 26 8 ,000
28 Sec. Kerosene 0.85 80°EH 130 2.66 3.37 240 11.0-11.5 12 32 10 ,000 2 ,000
28 Sec. Kerosene 1.00 80°EH 130 2. 5 3.74 245 11.5-12.0 16 35.5 121,000 32 10 ,000
35 Sec. Gas Oil* 0.50 80°H 260 2.44 2.87 220 11.5-12.0 28.5 7,000 26 8 ,000
35 Sec. Gas Oil* 0.55 80°H 265 2.76 3.25 235 11.5-12.0 14 32 10 ,000 2 ,000
35 Sec. Gas Oil* 0.55 80°H 330 3.06 3.60 240 12.0-12.5 16 35.5 121,000 32 10 ,000
NOMINAL BOILER RATING AT NORMAL OPERATING TEMPERATURE
26/ 2 Table 5. Electro Oil Sterling 40 Burner (See Fig. 26) Convential Flue Appliance (CF/LLD)
Fuel Nozzle
Pump
Pressure
(p.s.i.)
Fuel Flow
Rate Flue Gas
Temp.
(°C)** %CO2
Approx.
Air
Setting
Appliance
Input
kW Btu/hr kW Btu/hr
Output
Kg/h l/h
28 Sec. Kerosene 0.85 80°EH 110 2.36 2.PP 225 11.0-11.5 10 28.5 7,000 26 8 ,000
28 Sec. Kerosene 0.85 80°EH 130 2.66 3.37 240 11.0-11.5 15 32 10 ,000 2 ,000
28 Sec. Kerosene 1.00 80°EH 130 2. 5 3.74 245 11.5-12.0 20 35.5 121,000 32 10 ,000
NOMINAL BOILER RATING AT NORMAL OPERATING TEMPERATURE
26/ 2 Table 6. Electro Oil Sterling 40 Burner (See Fig. 26) RS Balanced Flue Appliance
Fuel Nozzle
Pump
Pressure
(p.s.i.)
Fuel Flow
Rate Flue Gas
Temp.
(°C)** %CO2
Approx.
Air
Setting
Appliance
Input
kW Btu/hr kW Btu/hr
Output
Kg/h l/h

6
4.1 The appliance is not suitable for external installation unless
a suitable enclosure is provided.
4.2. The appliance should be positioned on a non combustible
solid base as near to the flue location point as possible. Care
should be taken to ensure that the appliance is level; use
packing at the corners where necessary.
4. When fitting a LLD or RS model, the rear of the appliance
must be positioned against an external wall such that the flue
terminal can safely discharge the flue gases as described in
Section 7.
4.4. The following clearances must be left to allow access for
installation and servicing:
(a) Above - 300mm
(b) In front - 600mm
(c) Right and left hand side - sufficient for panel removal and
access to pipe connections where required.
See Figs. 3, 4, 5 and 6.
For installation and servicing of the appliance the cabinet panels
should be removed as follows:
5.1. Remove the cabinet top panel by lifting squarely upwards
to release the four ball stud connections.
5.2. Remove the front panel by pulling the bottom of the panel
forwards to release the ball studs and lifting the panel upwards
and forwards to release it from its supporting ledge.
5. . The side panels are removed by firstly following procedures
5.1 to 5.2 as described above, then remove screw (A) from the side
panel base and the three screws located in the upper flange of each
side panel. Ease the panel clear of the electrical control box and
slide forwards to release from the locating lugs on the base plate.
5.4 The control box can be removed by undoing the four screws
in the top access cover and then removing the wing nut on the
underside of the control box. The thermostat phials should be
carefully removed from the phial pocket, and the control box
placed in a safe place taking care not to kink the thermostat
capillary tubes.
5.5 On the RS balanced flue model, remove the burner box
cover by pulling forwards to release the ball studs. This will be
found easier by pulling on one side of the handle first to release
two ball studs and then repeating on the other side. Take care
not to pivot the remaining two ball studs too far around as this
will cause damage to the spring clips.
5. Removal of the Cabinet
4. Siting the ppliance
REAR VIEW
5
13
4
2
1. Alternative central heating return tapping.
2. Central heating flow (22mm compression).
3. Mains cold water in (15mm compression).
4. Pressure relief discharge pipe.
5. Domestic hot water out (22mm copper).
Boiler
152mm
168mm
112mm
Fig. 1. Pipework Dimensions.
795mm
809mm
813 mm
769mm
738mm
37mm
FRONT VIEWSIDE VIEW
CD
E
AB
H
F
G
Fig. 2. Principal Dimensions.
110mm
(12/14,15/19, 20/25 ) 780mm
775mm (26/32)
MODEL A B C D E F G H
12/14 520 600 855 780 110 2 57 184
15/19 520 600 855 780 110 2 57 184
20/25 520 600 855 780 110 2 57 184
26/ 2 670 600 855 775 110 2 52 260

7
Fig.3. 12/14, 15/19 and 20/25 Conventional Flue ppliance (CF/LLD).
Control Box ssembly
Front panel
Burner
Thermostat knob
Electrical control box
Control box top cover
User operating switch
(optional programmer
position)
Burner seal gasket
Isolating valve
Burner locking screw
Side panel
Top panel
Side panel locking
screw (A)
8
1. Hot water check valve. 8. Heatslave tank drain point (Unscrew 3⁄4turn to drain).
2. Automatic air vent. 9. Alternative central heating return tapping.
3. Diverter valve. 10. Flow switch.
4. Pump. 11. Mains cold inlet isolating valve.
5. System pressure gauge. 12. Air vent.
6. Pump manifold drain. 13. Pressure relief valve.
7. Fire valve clip.
6
5
4
12
13
3
12
11
1
712 10
9
2
Split pin
Split pin
Boiler high
limit
thermostat
phial
Central heating
control
thermostat
phial
Domestic hot
water control
thermostat phial
Manual reset high
limit thermostat
phial
Expansion
vessel

8
Fig.4. 12/14, 15/19 and 20/25 Room Sealed Balanced Flue ppliance (RS).
Control Box ssembly
Front panel
Burner
Burner cover
Thermostat knob
Electrical control box
Control box top cover
User operating switch
(optional programmer
position)
Burner seal gasket
Isolating valve
Rear air duct
Rear air duct
access cover
Burner locking screw
Side panel
Expansion
vessel
Top panel
Side panel locking
screw (A)
8
1. Hot water check valve. 8. Heatslave tank drain point (Unscrew 3⁄4turn to drain).
2. Automatic air vent. 9. Alternative central heating return tapping.
3. Diverter valve. 10. Flow switch.
4. Pump. 11. Mains cold inlet isolating valve.
5. System pressure gauge. 12. Air vent.
6. Pump manifold drain. 13. Pressure relief valve.
7. Fire valve clip.
6
5
4
12
13
3
12
11
1
7
12 10
9
2
Split pin
Split pin
Boiler high
limit
thermostat
phial
Central heating
control
thermostat
phial
Domestic hot
water control
thermostat phial
Manual reset high
limit thermostat
phial

9
Fig.5. 26/32 Conventional Flue ppliance (CF/LLD).
Electrical Box ssembly
Front panel
Burner
Thermostat knob
Control board
Electrical box top
cover
User operating switch
(optional programmer
position)
Burner seal gasket
Isolating valve
Burner locking screws
Side panel
Top panel
Side panel locking
screw (A)
1. Hot water check valve. 7. Alternative central heating return tapping.
2. Automatic air vent. 8. Flow switch.
3. Diverter valve. 9. Mains cold inlet isolating valve.
4. Pump. 10. Pressure relief valve.
5. System pressure gauge. 11. Air vent.
6. Pump manifold drain. 12. Fire valve clip.
6
5
4
3
10
9
1
8
7
2
Expansion
vessel
1010
1
11
Base plate locking
screw
12
Access cover locking
screw
Split pin
Split pin
Boiler high
limit
thermostat
phial
Central heating
control
thermostat
phial
Domestic hot
water control
thermostat phial
Manual reset high
limit thermostat
phial

10
Fig.6. 26/32 Room Sealed Balanced Flue ppliance
Electrical Box ssembly
Front panel
Burner
Burner cover
Thermostat
knob
Control board
Electrical box top
cover
User operating switch
(optional programmer
position)
Burner seal gasket
Isolating valve
Rear air duct
Rear air duct
access cover
Burner locking screws
Side panel
Expansion
vessel
Top panel
Side panel locking
screw
1. Hot water check valve. 8. Alternative central heating return tapping.
2. Automatic air vent. 9. Flow switch.
3. Diverter valve. 10. Mains cold inlet isolating valve.
4. Pump. 11. Pressure relief valve.
5. System pressure gauge. 12. Air vent.
6. Pump manifold drain. .
7. Fire valve clip.
7
5
4
12
3
10
1
9
8
2
6
11
Side panel locking
screw (A)
Base plate locking
screw
Electrical box top
cover
Thermostat
knob
Access cover locking
screw
Split pin
Split pin
Boiler high
limit
thermostat
phial
Central heating
control
thermostat
phial
Domestic hot
water control
thermostat phial
Manual reset high
limit thermostat
phial

OPEN FLUE MODEL (CF/LLD)
This includes conventional flue and standard low level and high
level horizontal discharge kits.
6.1 In order to ensure clean and efficient combustion, an
adequate supply of air must be delivered to the combustion
chamber. To provide sufficient air, a suitable inlet should be
provided into the room or space in which the appliance is
situated, the size of which is detailed in Table 7. An air brick or
other form of continuous air supply may have to be built into
the installation in order to ensure an adequate supply of air.
6.2 If the appliance is to be installed in a confined space or
compartment, two air vents are required, one at high level and
one at low level. The minimum free area of each vent is given in
Table 8 and depends whether the air is taken from another room
or from outside the building. Where the air is taken from another
room that room must contain an air inlet as described in 6.1.
6. There must be sufficient clearance around the appliance to
allow proper circulation of ventilation air. The clearances
required for installation and servicing will normally be adequate
for ventilation. See Section 4.4.
ROOM SEALED BALANCED FLUE MODEL (RS)
6.4 The appliance does not require a separate vent for
combustion air.
6.5 Installation in cupboards or compartments require
permanent vents for cooling purposes, one at high level and one
at low level, either direct to outside air or to a room. Both vents
must pass to the same room or be on the same wall to the
outside wall to the outside air. The minimum air vent free area is
given in Table .
6.6 There must be sufficient clearance around the appliance to
allow proper circulation of ventilation air. The clearances
required for installation and servicing will normally be adequate
for ventilation. See Section 4.4.
A flue system must be provided in accordance with BS5410:
Part 1 and with the current Building Regulations.
7.1 Conventional Flue (CF). See Fig 5.
Conventional Flue Diameters: 12/14 – 100mm (4in.)
15/1 – 100mm (4in.)
20/25 – 100mm (4in.)
26/32 – 125mm (5in.)
NOTE: External flues systems must be of the insulated flue type.
The boiler is fitted with a conventional flue locating spigot.
7. Flue System6. ir Supply
11
Fig. 7. Flue Installation.
Where possible take the
flue above the apex –if not
above the apex an anti
down-draught terminal is
advisable.
Brick Chimney.
Use of a flue liner
is recommended.
Use as few bends as
possible.
Use 135°Bends.
Flues must not be reduced from
the boiler take off diameter.
ALWAYS TAKE THE FLUE ABOVE THE EAVES
Fig. 8. Flue Installation (Rear Discharge).
See Fig. 10 for flue
terminating positions.
80
min.
FLUE GUARD
766 mm
140
Table 8. Minimum Air Vent Free Area for Open Flue
appliances installed in a compartment.
Appliance Ventilation to room or Ventilation to outside
model internal space
High Level Low Level High Level Low Level
12/14 154cm2231cm277cm2154cm2
15/1 20 cm2314cm2105cm220 cm2
20/25 275cm2413cm2138cm2275cm2
26/32 352cm2528cm2176cm2352cm2
Table 9. Minimum Air Vent Free Area for Room Sealed
appliances installed in a compartment.
Appliance Ventilation to room or Ventilation to outside
model internal space
High Level Low Level High Level Low Level
12/14 154cm2154cm277cm277cm2
15/1 20 cm220 cm2105cm2105cm2
20/25 275cm2275cm2138cm2138cm2
26/32 352cm2352cm2176cm2176cm2
APPLIANCE AREA OF AIR INLET
cm2in.2
12/14 77 12
15/1 105 16.5
20/25 138 21.5
26/32 176 27.5
Table 7. Minimum Combustion Air Inlet Free Area for
Open Flue appliances

12
FLUE GUARD
X = 180 mm Maximum
X = 327 mm Maximum
One extension kit –X = 638 mm Maximum
Two extension kits –X = 952 mm Maximum
766 mm
X
X
340 mm
270 mm
Fig. 9. Room Sealed Balanced Flue Terminal Installation.
(b) Rear Discharge 7" to 12" Wall.
For use in standard cavity walls and solid walls
up to 327 mm thick. This terminal offers
maximum noise reduction of the flue gases.
This terminal is designed for use with the
extension kit.
(a) Rear Discharge 4" to 7" Single Skin Wall.
For use with non-standard/single skin walls up to
182.mm thick.
Where noise emission from the flue terminal is likely to
be of concern, it is recommended that the standard 12 in.
terminal is used and the appliance stood away from the
wall to take up the extra terminal body length.
(c) Rear Discharge Extension Kit
12" to 36" Wall.
X
For use where the wall thickness exceeds
327.mm or where the appliance is to be stood
away from the wall as shown. The system uses a
standard 12 in. RS Flue Terminal and up to two
extension kits, which simply bolt together.

The flue pipe fits into the spigot and should be correctly sealed
with fire cement.
NOTE: The flue size must never be reduced from the take-off
diameter. An increase in flue size is permissible provided that
the joint is sealed correctly.
The flue should be vertical and contain as few bends as possible.
Where bends are necessary, a maximum of two are permitted
and 135° bends should be used.
All brick and masonry chimneys should be lined with a suitable
non-combustible material. They must be properly jointed and
able to withstand the effects of the working temperature of the
appliance and any condensate which may form.
Down-draught conditions will adversely affect the operation of
the appliance and must be avoided. Where possible, the flue
should be extended beyond the apex of the roof and should
always be taken beyond the eaves of the building. Where down-
draught is experienced a suitable anti-down-draught terminal
should be fitted to the flue termination.
The natural flue draught must be checked. A suitable location for
checking this is located in the flue outlet plate on top of the boiler.
The draught should be no less than 0.75mm w.g and no greater
than 5.1mm w.g. If a flue draught greater than 5.1 mm w.g is
experienced a draught stabiliser should be fitted to the flue and
adjusted to achieve a flue draught within the specified range.
7.2 Low Level Discharge (LLD)
See Fig 8.
The conventional flue appliance may be converted to discharge
the products of combustion at low level. For this purpose a
special flueless kit and associated ducting is available, allowing
the conventional flue to be discarded. Detailed instructions for
converting the appliance to low level discharge are supplied
with the conversion kit. The flue spigot should be removed from
the flue outlet plate by undoing the three retaining screws and
the hole blanked off with the plate provided in the kit.
NOTE: Under no circumstances may 5 Second Gas Oil be
burned with this type of flue terminal arrangement.
7. Room Sealed Balance Flue Model (RS)
The appliance is supplied ready for installation as a low level
discharge balanced flue system by the simple addition of one of
the flue terminal options shown in Fig. .
Details of the installation procedure are included in the Flue
Terminal Installation Instructions supplied with the terminal kit.
Alternatively, a range of room sealed balanced flue kits are
available to convert the appliance to discharge the flue products
to the left, right, at a higher level, or vertically up to a roof height
of 4.5 metres.
1
L
F
F
K
G
A
E
B
C.D.
J
N
O
M
H
F
Boundry
Boundry
P
M
Minimum Distance (mm)
Terminal Position Open Low-Level Vertical
Flue Discharge Balanced Flue
ADirectly below an opening, air brick, window, etc. .......................................... Not allowed 600 Not allowed
B Horizontally to an opening, air brick, window, etc. ........................................ Not allowed 600 ''
C Below a gutter or sanitary pipe if combustible material protected. .............. Not allowed 75 ''
D Below a balcony, eaves, gutter or drainage without protection
to combustible material. ...................................................................................... Not allowed 600 ''
E From vertical sanitary pipework.. ....................................................................... Not allowed 300 ''
F From an internal or external corner or boundry along side terminal. .......... Not allowed 300 ''
G Above ground or balcony level. .......................................................................... Not allowed 300 ''
H From a surface or boundry facing the terminal. .............................................. Not allowed 600 ''
J From a terminal facing the terminal. ................................................................. Not allowed 1200 ''
K Vertically from a terminal on the same wall. ................................................... Not allowed 1500
L Horizontally from a terminal on the same wall. .............................................. Not allowed 750 ''
M Above an intersection with the roof. ................................................................. 600 Not applicable 732
N From a vertical structure on the side of the terminal...................................... 750 Not applicable 750
O Above a vertical structure less than 750mm from the side of the terminal. 600 Not applicable 732
P From a ridge terminal to a vertical structure on the roof................................ 1500 Not applicable Not applicable
NOTE: The dimensions given are for general guidance only. Other surrounding buildings or objects may affect the clearance of
combustion products. An alternative flue terminal position should be sought when there is any possibility of a nuisance being
caused by inadequate dispersal of flue products.
Terminals should be positioned so as to avoid products of combustion entering into buildings.
Fig. 10. Flue terminating positions for oil-fired appliances
Window
Flue
Terminal

14
7.4 Siting the flue terminal
1. The flue terminal must be located in a suitable position, as
shown in Fig 10, such that products of combustion can be freely
dispersed without the possibility of flue gases entering dwelling
or that of a neighbouring dwelling.
2. Discharge of flue gases into carports or narrow passageways
is not recommended.
. The terminal must not cause obstruction nor the discharge
cause a nuisance as a result of either flue gases or terminal
noise.
4. If the terminal is fitted within 1 m of a plastic or painted
gutter or within 500 mm of painted eaves then an aluminium or
stainless steel shield at least 1 m long should be fitted to protect
the surface.
5. If a terminal is fitted less than 2 metres above a surface to
which people have access, fit a terminal guard as shown in Fig 11.
A suitable guard is available from Worcester Heat Systems, Part
number 7 716 1 0 00 , or alternatively a proprietary terminal
guard may be used provided it has the minimum dimensions
shown in Fig 11. The guard should have suitable corrosion
resistance due to the acidic content of the flue gases.
6. The terminal guard must be evenly spaced about the flue
terminal and secured using screws, to allow access to the flue
terminal.
7. In certain weather conditions a terminal may steam and
siting where this could cause a nuisance should be avoided .
8. Take care to ensure that combustion products do not enter
ventilated roof voids.
Fig. 11. Terminal guard Minimum dimen-
265
280
280
Terminal guard.
See 7.4.5.

(See Figs. 12, 13 and 14).
8.1 Plastic or steel tanks should be installed to BS5410.
A steel tank should also conform to BS7 : part 5 and be arranged
with a slope of 1 in 24 away from the outlet valve with a sludge
cock at its lower end.
8.2 Do not use galvanised steel tanks or pipework for the oil
supply system.
8. Do not use soldered joints in the oil supply pipework as this
could cause a hazard in the case of a fire.
8.4 The burners on all appliances are supplied so as to be
connected to a single pipe gravity feed system. Details of how to
convert the burners to a double pipe sub-gravity feed system
are shown in Fig. 12
8.5 Oil Supply System
(a) Single Pipe System
If a single pipe system is employed, then the tank must be
positioned such that the oil level does not exceed 4 metres
above the level of the burner oil pump and in addition the oil
level must be at least 0.3 metres above the level of the oil pump.
Should it prove impossible to site the tank below the 4 metres
maximum oil level head breaking device must be installed
between the tank and the burner.
(b) Double Pipe System
If a double pipe system is used then the maximum suction
height allowable is 3.5 metres.
(c) Single Pipe Suction Lift with De-aerator
If a single pipe suction lift with a de-aerator is used, the oil tank must
be positioned below the burner. An inlet and return loop should be
created between the de-aerator and oil pump. The oil pump should be
connected as for a double pipe system. Details of how to convert to a
double pipe system are shown in Fig. .
Oil inlet and return flexible hoses should be connected to the oil
pump inlet and return ports.
Table 12 is a general guide to determine the maximum allow-
able pipe run when using a de-aerator.
Table 12 does not override the de-aerators manufacturers
instructions and should only be used in conjunction with the
manufacturers instructions.
If a non-return valve is not incorporated within the de-aerator
unit, a non-return valve should be fitted in the oil line between
the oil tank and the de-aerator.
NOTE: If a de-aerator is used it should be fitted externally to the building.
8.6 Oil Supply Pipework
a) The oil supply pipe diameter can be determined using Tables 10,
11 and 12 depending on whether a single or double pipe system or
single pipe suction lift system is being installed. Selection of the
correct pipe diameter will depend on the position of the oil storage
tank relative to the burner and the length of pipe run.
b) The oil supply pipe should be laid as level as possible to avoid
air pockets and unnecessary friction losses.
c) The following components should be fitted in the fuel line
between the storage tank and burner:
1. A Manual isolating valve installed as close to the tank as possible.
2. A fire valve in accordance with BS5410, Part 1 as shown in Fig
11. The fire valve should be fitted externally with a fire detection
element located within the appliance case. Use of a capillary type
valve will allow a neat and simple installation. A suitable valve is the
KBB manufactured by Teddington Controls Limited. A spring clip
has been provided behind the electrical panel on CF/LLD models,
shown in Fig 3 and 5, and on the burner box on RS models, shown
in Fig 4 and 6, to allow a fire valve element to be mounted.
Alternatively a fusible link or electrical system may be used. Under
no circumstances should a combination isolating/fire valve be used
as the sole fire protection device.
. An oil filter should be fitted close to the oil storage tank. If
there is doubt about the internal oil line condition, a further filter
should be fitted near the boiler.
8. Oil Supply
15
Fig. 12. Oil Pump.
B. Danfoss BFP 11 Oil Pump.
. Danfoss BFP 41.
C. Suntec S47C Oil Pump.
Cartridge filter
12
3
4
4a
5
6
1
2
3
4
5
6A
1 INLET
2 RETURN
3 BLEED AND PRESSURE
GAUGE PORT
4 VACUUM GAUGE PORT
5 PRESSURE ADJUSTMENT
6 NOZZLE OUTLET
To convert to a double pipe sys-
tem, remove plug 4a and insert
the grub screw provided into the
threaded hole. Connect flow and
return pipes to (1) and (2).
To convert to a double pipe sys-
tem: Remove the pump front
cover, remove the changeover
screw (A) nearest to ports 1 and
2, and the horseshoe washer
underneath. Replace the
changeover screw back into the
threaded hole. Connect the flow
and return pipes to 1 and 2.
Note: When removing the pump
front cover ensure that a suitable
receptacle is placed below the
pump to catch the oil residue.
To convert to a double pipe sys-
tem, remove the return port plug
(2) and insert the grub screw (A)
provided into the threaded hole
(B). Connect flow and return pipes
to (1) and (2).
1
2
3
3
4
5
B
A
TABLE 10 Single Pipe Gravity Feed System
MAXIMUM ALLOWABLE PIPE RUN
HEAD (metres) (metres)
8 mm inside dia. pipe 10 mm inside dia. pipe
(10 mm O.D. copper) (12 mm O.D. copper)
0.5 12 30
1.0 25 6
1.5 37 1
2.0 4 100
2.5 62 100
3.0 74 100
3.4 87 100
4.0 100
TABLE 11 Double Pipe Sub-Gravity Feed System
MAXIMUM ALLOWABLE PIPE RUN
HEAD (metres) (metres)
8 mm inside dia. pipe 10 mm inside dia. pipe
(10 mm O.D. copper) (12 mm O.D. copper)
0 50 100
0.5 44 100
1.0 38 5
1.5 32 80
2.0 26 66
2.5 20 51
3.0 14 37
3.5 8 22

16
MAXIMUM ALLOWABLE PIPE RUN FROM TANK TO DE-AERATOR (metres)
Fuel
Flowrate 2.5 (kg/h) 5.0 (kg/h) 10.0 (kg/h) 10.0 (kg/h)
HEAD
(metres) 6 mm inside dia. pipe 8 mm inside dia. pipe
(8 mm O.D. copper) (10 mm O.D. copper)
0 100 55 26 100
0.5 5 45 23 100
1.0 80 40 20 0
1.5 70 35 17 75
2.0 60 30 14 65
2.5 45 25 11 50
3.0 35 15 8 35
3.5 25 10 5 20
Fig. 13. Oil Supply.
(a) Single pipe system
Oil tank
Oil tank
Maximum oil level
H = 4 m (13 ft) maximum
Fire valve to
BS 5410 Part 1
Fire valve to
BS 5410 Part 1
Isolating
valve Isolating
valve
Fire detection
element
Filter
Burner
Burner
Wall
Wall
(b) Double pipe system.
Isolating
valve
Non return
valve
Non return
valve Fire detection
element
Isolating
valve
Oil tank
(c) Single pipe lift system with de-aerator.
Fire valve to
BS 5410 Part 1
H = 3.5 m (11.5 ft) maximum
Burner
Wall Fire detection
element
De-aerator
H = 3.5 m (11.5 ft) maximum
TABLE 12 Single Pipe Suction Lift with De-aerator
Isolating
valve
H = 0.3 m (1 ft) minimum
Paper element
oil filter
Isolating
valve
Filter
Filter
Isolating
valve Isolating
valve
Full base
(for plastic tanks)
Full base
(for plastic tanks)
Full base
(for plastic tanks)
150 mm

17
Fig. 14. Oil Pipe Installation.
(b) Single Pipe System.
RS ppliance
(a) CF Bracket.
CF ppliance
(c) Double Pipe System or
Single Pipe Suction Lift with De-aerator.
Burner
oil pump
Open
grommet
Turn fully
clockwise
to isolate
Blind
grommet
Air
bleed
Burner
oil pump Burner
oil pump
10mm or 12mm
copper pipe
1⁄4" BSP female x
10/12mm
compression coupling
(not supplied)
10mm
copper pipe
10mm
copper pipe Retaining
clip
Isolating
valve
Isolating
valve Pipe support
bracket
Turn fully
clockwise
to isolate
Flexible
oil hose
The heating and hot water system must be provided in accor-
dance with the current Building Regulations.
9.1 The appliance incorporates a circulating pump. No other
pump is required. The appliance will operate satisfactorily on a
two-pipe small bore or micro bore system using
thermostatically controlled radiator valves.
9.2 The appliance incorporates a three-port, two-way diverter
valve which diverts the boiler output to the Heatslave tank in
response to a demand from the Domestic Hot Water Control
Thermostat or the flow switch. The valve is powered open in
response to a demand from the Central Heating Control
Thermostat or a room thermostat, and the boiler output is
diverted to the heating circuit.
If there is a demand from both the Heatslave tank and the
central heating, the valve will give priority to the Heatslave tank.
The central heating will therefore remain switched off for a short
period of time. This delay will vary depending on the appliance
output and the quantity of energy required to satisfy the
domestic hot water demand.
The Heatslave tank priority can be temporarily overridden to
regain the central heating output by turning the Domestic Hot
Water Thermostat fully anti-clockwise for the duration of the
warm up period. This will prevent the Heatslave tank taking
priority for the tank warm up period of approximately 20
minutes and may be found advantageous to give quicker
heating to the dwelling when starting from cold.
9. On new installations it is recommended a room thermostat
or programmable room thermostat is used in the main zone and
thermostatic radiator valves are used in further heating zones.
On existing systems where a room thermostat is already fitted it
is recommended to fit thermostatic radiator valves at least in
the sleeping areas.
9.4 A check valve is incorporated in the hot water primary
circuit to prevent gravity circulation from the tank to the boiler.
9.5 When employing a central heating system where primary
water flow may be prevented during a pump overrun situation
(e.g. by using thermostatic radiator valves on all radiators), a
bypass valve should be fitted between the flow and return pipes.
9.6 The pressure jet burner fitted to the appliance has full automatic
control and there is no requirement for heat leak radiators.
9.7 It is strongly recommended that isolating valves are fitted to
the central heating flow and return pipes. This will allow the
boiler and Heatslave tank to be drained for service work without
having to drain down the whole central heating circuit.
9.8 A drain point should be provided in the domestic hot water
pipework at any point below the height of the domestic hot
water heat exchanger.
9.9 Provision should be made to allow air to be vented from the
domestic hot water pipework at any high points. Failure to vent
the air will cause the flow switch to operate momentarily if a
cold water tap is turned off rapidly.
9.10 Any unused boiler tappings should be plugged prior to
filling.
9.11 The primary central heating system should be flushed and
treated in accordance with recommendations of BS 75 3: 1 2
before the system is handed over to the user.
9.12 System Pipework
Sealed System Pipework (See Figs. 15 and 16).
Copper pipework must be used when installing the appliance on
a sealed system.
Open Vent Primary System Pipework (See Figs. 17.)
The first meter of pipework from all appliance connections must
be in copper; afterwards copper or plastic pipe can be used. The
plastic pipe must be manufactued to BS 72 1 and installed to BS
5 55 part 8. It is recommended to protect the system
components the plastic pipe specified is resistant to the ingress of
oxygen.
9. System Considerations

18
Fig. 15. Sealed Primary System.
Domestic hot
water outlet
Mains cold isolating valve
Heating flow (22 mm)
Water main
Heating return (22 mm)
Domestic cold water
Note: The appliance mains
cold water supply should be
the first connection off the
water main
British Standard stop valve
(Fixed spindle type)
Static head of system
Expansion vessel
Pressure gauge
Pump
Heatslave
tank To system filling device
See Fig. 16
Flow switch
Pressure relief valve
Diverter valve
See Figs. 15 and 16.
10.1 The system must comply with the requirements of BS
7074:1 and BS 544 :1.
10.2 A manual reset overheat thermostat is located on the
underside of the electrical panel and is accessible by removing
the cabinet front panel. If a boiler overheat condition arises the
burner will remain inoperative until the thermostat button is
reset. See Fig. 3, 4, 5 and 6.
10. The pressure relief valve operates at 3 bar (45 lb/in2). The
discharge must be directed away from the electrical
components or where it might be a hazard to the user.
10.4 The pressure gauge, located in the pipe below the pump,
indicates the system pressure which must be maintained.
10.5 The 12 litre expansion vessel is charged to 0.5 bar and is
suitable for a static head of 5 metres (17.5 ft). The pressure can
be increased for a static head greater than 5 metres (17.5 ft).
10.6 With an initial system pressure of 0.5 bar, a system
capacity of about 180 litres can be accommodated. Refer to BS
7074 Pt 1 for more information.
Where the system volume exceeds the value given in Table 13 an
additional expansion vessel, of suitable volume, should be fitted
to the heating return pipework as close to the boiler as possible.
NOTE: The values given in Table 13 are the total system volumes.
The primary water capacity given in Table 1 should be deducted
from the total system volume when calculating the volume for
radiators, pipework etc.
10.7 The method of filling the appliance can be either method 1
or 2 shown in Fig 16. The filling point must be at low level and
must never be a permanent direct fixing to the mains water
supply.
10.8 Water loss must be replaced, see Fig 14. The connection
should be made to the central heating return pipe as close to the
appliance as possible.
10.9 The make-up vessel, where used, must be fitted with a non-
return valve.
10.10 Repeated venting loses water from the system. It is
essential that this water is replaced and the system pressure
maintained.
10.11 Connections to the mains water supply must not be
made without the authority of the local Water Company.
10.12 The appliance incorporates a circulating pump. No other
circulating pump is required. The pump is factory set to the
maximum setting (No: 3) and should not be altered as this
would affect the domestic hot water performance.
10.1 Connections in the system must resist a pressure of up to
3 bar.
10.14 Radiator valves must conform to BS 2767 (10).
10.15 Other valves used should conform to the requirements of
BS 1010.
10. Sealed Primary System
Automatic bypass valve to be fitted
where thermostatic radiator valves are
fitted on all radiators

19
See Fig 17.
The appliance is supplied ready for connection to a Sealed Water
system. Where the appliance is to be used with an Open Vent
System, the pressure relief valve may be removed and the
tapping blanked off. If the relief valve is left in position, a
discharge pipe should be fitted. The pipe must be directed away
from the electrical components or where it might be a hazard to
the user.
The following points are for guidance only. The system
installation should be carried out in accordance with BS 544 .
Part 1.
11.1 The feed and expansion pipes must rise continuously from
the appliance. The feed pipe must be at least 15mm diameter
and the expansion pipe must be at least 22mm diameter. If
access to the 1" BSP sockets on the right hand side of the boiler
is difficult, use the alternative return connection on the boiler
pipework. See Figs. 3, 4, 5 and 6.
The cistern must be arranged to provide a minimum static head
of 1 metre (3 ft) above the top of the appliance casing or the
highest point in the heating circuit. See Fig 17.
11.2 Air in the appliance is expelled through the vent pipe or
dissipated into the system, but manual air vents should be fitted
at high points in the system. An automatic air vent is fitted to
the Heatslave tank and manual air vents are included on high
points in the appliance pipework.
11. The appliance incorporates a circulating pump. No other
circulating pump is required. The pump is factory set to the
maximum setting (No: 3) and should not be altered as this
would affect the domestic hot water performance.
11. Open Vent Primary System
Fig. 17. Open Vent Primary System.
Domestic hot
water outlet
350 mm (14.0 in.)
minimum
Minimum static head to be 1m
(3ft) measured from the top
surface of the appliance or the
highest point in the heating
system to the top of the water
level in the expansion tank.
Expansion cistern
Static head
Static head
Mains cold isolating
valve
Heating flow (22 mm)
Water main
Heating return (22 mm)
Domestic cold water
Note: The appliance mains
cold water supply should be
the first connection off the
water main
British Standard stop valve
(Fixed spindle type)
Primary cold feed (15 mm)
Heating vent (22 mm)
Diverter
valve
Boiler
Pump
Heatslave
tank
Flow switch
TABLE 1
TOTAL SYSTEM VOLUME (Litres)
Initial System Initial Charge Pressure (bar)
Pressure (bar) 0.5 1.0 1.5
0.5 180 – –
1.0 107 138
Heating return
Non return
valve Non return valve Hose union
Test cock Temporary hose
Stop cock
Auto
air vent
Heating return
Stop
cock
Fill point
Non return
valve
Make up
vessel
300 mm (12 in) min.
above the highest
point of the system.
Fig. 16. System filling and make-up.
Method 1 Method 2
Automatic bypass valve to be fitted
where thermostatic radiator valves are
fitted on all radiators

20
The following are general requirements and, if necessary,
reference should be made to the local Water Company before
fitting the appliance.
12.1 Mains Cold Water Inlet
Devices capable of preventing the flow of expansion water must
not be fitted unless separate arrangements have been made. An
expansion vessel can be fitted within the casing of the appliance
if necessary.
The final 600mm of the mains cold water connection to the
appliance should be made in copper tube only.
The appliance is suitable for a mains cold water supply having a
maximum pressure of up to 10 bar (145 lb/in2). A pressure
reducing valve must be fitted if the mains pressure exceeds 10
bar.
12.2 Domestic Hot Water Supply and Flow Regulation
As with all mains fed systems, the flow rate of water obtainable
from individual taps will vary in relation to the number of
outlets operated simultaneously.
The flow rate will depend on the cold mains supply pressure
available to the property and the diameter and length of
pipework making up the domestic water distribution system.
When more than one outlet is used at once, starvation of water
flow may occur at one or more outlets. Where this is a problem
flow balancing valves or Ball-O-Fix valves should be installed at
the appropriate outlets.
The 12/14 and 15/1 appliances are fitted with a water flow
restrictor. The maximum flow of domestic hot water available
from the appliances is 15 litres/min (+ or - 15%) (3.3
gallons/min) and requires a minimum mains cold supply
pressure of 1.6 bar (22 lb/in2) to attain this level.
The 20/25 and 26/32 appliances are not fitted with a flow
restrictor and therefore the flow rate is only limited by the water
supply pressure. This can be manually adjusted at the mains
cold water inlet isolating valve. The maximum recommended
domestic hot water flow rate from the 20/25 appliance is 17
litres/min (3.7 gallons/min). The maximum recommended
domestic hot water flow rate from the 26/32 appliance is 22
litres/min (4.8 gallons/min).
The temperature of hot water drawn will vary with the flow rate
at the taps and the appliance operating temperatures. It is usual
that flow rates (and thus temperatures) are controlled at the tap,
but if a more permanent setting is required, a mixing valve can
be fitted.
If there are long pipe runs to the taps or shower, it is
suggested that they be insulated to prevent the rapid cooling
of residual hot water in the pipes after the tap has been
turned off.
NOTE: The flow restrictor contained within the flow switch
housing is plastic. Do not allow the housing to become hot
during soldering operations.
12. Taps and Valves
Hot and cold taps and mixing valves used with this appliance
must be suitable for operating at a mains pressure of up to 10
bar (145 lb/in2).
12.4 Showers (Fixed Head Type)
No anti-syphonage arrangements are necessary.
Thermostatically controlled shower valves will give extra
comfort and guard against the flow of water at too high a
temperature.
12.5 Showers (Loose or Flexible Head Type)
A loose head shower hose must be fixed so that the head cannot
fall closer than 25mm (1 in) above the top edge of the bath to
prevent its immersion in bath water. Alternatively the shower
must incorporate or be fitted with an anti-syphonage device at
the point of the flexible hose connections.
Thermostatically controlled shower valves will give extra
comfort and guard against the flow of water at too high a
temperature.
12.6 Bidets
The supply of hot and cold mains water direct to a bidet is
permitted (subject to local Water Company requirements)
provided that the bidet is of the over-rim flushing type. The
outlet(s) should be shrouded and unable to have any temporary
hand held spray attached. No anti-syphonage arrangements are
necessary.
12.7 Use in Hard Water Areas
In areas of exceptionally hard water supply, it is recommended
that an In-line scale inhibitor be fitted.
Installation should be strictly in accordance with the
requirements of the local Water Company. An isolating valve to
facilitate servicing should be incorporated.
The water hardness may be determined using the standard test
paper or by reference to the local Water Company.
Further information may be obtained from Worcester Heat
Systems Ltd.
IMPORTANT: Where back-flow prevention devices, including
water meters, are fitted the expansion of hot water into cold
water main can be prevented. This can result in a pressure
build-up that may cause damage to the boiler and household
devices such as showers, washing machines etc.
In these cases we recommend that a mini-expansion vessel
be fitted adjacent to the boiler in the cold water pipe.
12. Domestic Hot Water