Worcester Highflow 400 BF User guide

Highflow 400
BF
FLOOR STANDING COMBINATION APPLIANCE FOR CENTRAL
HEATING AND MAINS FED DOMESTIC HOT WATER
INSTALLATION AND
SERVICING INSTRUCTIONS
BOILER OUTPUT
To Hot Water On/Off Control
Maximum 24.0 kW (82,000 Btu/h)
To Central Heating On/Off Control. Range Rated
Minimum 8.8 kW (30,000 Btu/h)
Maximum 24.0 kW (82,000 Btu/h)
IMPORTANT: THIS APPLIANCE IS FOR USE WITH NATURAL GAS ONLY
THESE INSTRUCTIONS APPLY IN THE UK ONLY
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE GAS METER
This appliance must be installed by a competent person in accordance
with the Gas Safety (Installation and Use) Regulations 1998
Bosch Group
GC NUMBER 47 311 19

1.1 Gas Safety (Installation and Use) Regulations 1994 as
Amended in 1996: All gas appliances must be installed by a
competent person in accordance with the above regulations.
Failure to install appliances correctly could lead to prosecution.
1.2 The manufacturers notes must not be taken, in any way, as
overriding statutory obligations.
1.3 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: Gas Safety (Installation
and Use) Regulations 1994 (as Amended in 1996), current IEE
Wiring Regulations, local Building Regulations, Building
Standards (Scotland) (Consolidation), byelaws of the local Water
Company and Health and Safety Document No. 635 (Electricity
at Work Regulations 1989). The British Gas Material and
Installation Specification for central heating and hot water. It
should be in accordance with the relevant recommendations of
the following British Standards:
BS 6798:1987 Specification for Installation of gas fired hot water
boilers of rated input not exceeding 60 kW
BS 5449:1990 Central Heating for Domestic Premises
BS 5546:1990 Installation of gas hot water supplies for domestic
purposes.
BS 5440:1:1990 Flues and Ventilation for gas appliances of rated
input not exceeding 60kW: Flues.
BS 5440:2:1989 Flues and ventilation for gas appliances of rated
input not exceeding 60kW: Air Supply.
BS 6891:1988 Installation of low pressure gas pipework
installations up to 28mm (R1)
1.4 To ensure that the installation will perform to the highest
standards, the system and components should conform to any
other relevant British Standards in addition to those mentioned
in the instructions.
1.5 The appliance complies with the Essential Requirements of
the Gas Appliance Directive and other Directives currently
applicable.
1.6 This appliance contains no asbestos products. There is no
potential hazard due to the appliance being electrically unsafe.
There are no substances used that are a potential hazard in
relation to the COSHH Regulations 1988.
2.1 This appliance is not suitable for external installation.
2.2 The appliance controls are set to provide a maximum
output of 24 kW for the hot water and a central heating load of
up to 24 kW.
2.3 A permanent pilot is used to provide ignition.
2.4 PRINCIPLE APPLIANCE COMPONENTS
A low thermal capacity Gas to Water heat exchanger
A water to water heat exchanger to provide hot water.
A heatbank having a nominal capacity of 60 litres of circulating
primary hot water positioned in the lower half of the appliance.
A water diverter valve to direct the boiler output either to hot
water or central heating as required.
Multifunctional gas valve and electrical control system to
individually control the hot water and central heating.
An integral circulating pump.
Boiler and hot water temperature control thermostats providing
control for central heating and hot water.
A User’s Operating Switch for selection of water only or heating
and water.
A by-pass for central heating system.
An electronic control board which enables the pump to run on
for a period of a about five minutes to allow the boiler section to
cool after each operating cycle.
An expansion vessel, pressure gauge and pressure relief valve.
Temperature safety cut-out controls.
A water flow regulator and flow switch in the domestic supply.
A standard horizontal rear flue kit to accommodate a flue length
of 229mm to 407mm.
An optional flue kit to provide for flue lengths up to a maximum
of 610mm.
2.5 ELECTRICAL SUPPLY
Mains supply: 230V ~ 50Hz, 150 watts. External fuse 3A.
Internal fuse 3.15A (20mm) fast blow.
2.6 GAS SUPPLY
The boiler requires 2.84 m3/h (100.3 ft3/hr ) of gas with a
calorific value of 37.78 MJ/m3. (1014 Btu/ft3.) The gas meter and
supply pipes must be capable of supplying this quantity of gas
in addition to the demand from any other appliances being
served. The following table gives an indication of limiting gas
pipe lengths and the allowance to be made for fittings. Refer to
BS 6891 for further information.
The meter governor should deliver a dynamic pressure of 20
mbar (8in wg.) at the appliance.
The complete installation including the gas meter must be tested
for soundness and purged. See BS 6891.
2. General Information
1. Installation Requirements
2
10. Electrical ...................................................................... Page 11
11. Installing the Appliance ............................................ Page 13
12. Commissioning the Appliance ................................ Page 18
13. Instructions to the User ............................................ Page 20
14. Inspection and Service .............................................. Page 20
15. Replacement of Parts ................................................ Page 21
16. Operational Flow Diagrams ...................................... Page 36
17. Fault Finding .............................................................. Page 38
18. Component Parts List ................................................ Page 44
1. Installation Requirements ........................................ Page 2
2. General Information .................................................. Page 2
3. Technical Data ............................................................ Page 5
4. Siting the Appliance .................................................. Page 6
5. Flue Terminal Position ................................................ Page 8
6. Air Supply .................................................................... Page 8
7. Sealed System ............................................................ Page 9
8. Open Vent System ...................................................... Page 10
9. Hot Water Supply ........................................................ Page 10
Contents
Total Length of Gas Supply Pipe (metres)
369
8.7 5.8 4.6 22
18.0 12.0 9.4 28
Gas
Discharge
Rate (m3
/hr)
Pipe
Diameter
(mm)

2.7 PACKING
The appliance and flue components are packed in separate
cartons.
2.8 GENERAL INSTALLATION
The appliance is supplied for connection to a sealed system but
is suitable for use with an open system.
The specified ventilation openings made into a wall or
compartment door must not be obstructed.
If the appliance is to be fitted into a compartment then the
compartment must conform to the requirements of BS 6798:
1987:Section 6.
The clearances specified for installation and servicing must be
maintained.
2.9 FLUE
The appliance has a balanced flue system.
A terminal guard, Type E, GC No 393 547, is available from Tower
Flue Components, Vale Rise, Tonbridge, TN9 1TB.
The standard horizontal flue assembly length is from 229mm to
407mm.
Extended flue lengths up to 610mm are available using the
optional extended flue kit.
Do not allow the flue terminal fitted to the outside wall to
become obstructed or damaged.
2.10 CONTROLS
The electronic control system via the gas valve operates the heat
input in response to the central heating and hot water
temperature settings.
The Operating switch provides for the selection of hot water
(WATER) only or central heating and hot water (HEATING and
WATER) or OFF.
A facia mounted programmer is available as an optional extra. A
remote mounted programmer may be connected to the
appliance.
The control thermostats for central heating and hot water are
mounted on the integral facia.
There is provision for the connection of a mains voltage room
thermostat. Refer to Section 10.
Frost Protection. When the appliance and heating system are
exposed to low temperatures it is advised to fit a frost
thermostat Refer to Section 10.
Thermostatic radiator valves can be used in the system. The
appliance incorporates an adjustable by-pass between the
central heating flow and return.
3
Return Valve
Flow Valve
Water Manifold
(Top Section)
Manual Air Vent
Pressure Relief
Valve
By-Pass
Adjuster
Water to Water
Heat Exchanger
Water Manifold
(Bottom Section)
Water Diverter
Valve
Open Vent
Position
Drain
(Secondary Water)
Circulating
Pump
Drain
(Primary Water)
Heat-Bank
Capacity 60 Litres
Sealed System
Expansion
Vessel
Boiler
2
Gas to Water
Heat Exchanger
Appliance
Cabinet
Central
Heating
Flow
Central
Heating
Return
Domestic
Hot Water
Out
Mains Cold
Water In
Water Filter Flow Switch
Automatic Air
Vent Water Flow
Regulator
3
4
5
1
Fig. 1. Appliance water flow diagram.
C.H. Thermostat ZAGAS041 Heatbank Overheat Thermostat ZAGAS044
Safety Temperature Limiter SSAHAR013 H.W. High Limit Thermostat SSAHAR253
H.W. Thermostat ZAGAS042
1
2
3
4
5

2.11 SYSTEM NOTES
WARNING
CHECK THAT NO DIRT IS LEFT IN EITHER THE GAS OR WATER
PIPEWORK AS THIS COULD CAUSE DAMAGE TO THE APPLIANCE.
THE BOILER AND SYSTEM SHOULD BE FLUSHED OUT AND
CLEANSED AS PER BS 7593. THE DOMESTIC WATER SUPPLY
SHOULD BE THOROUGHLY FLUSHED AND THE GAS SUPPLY
PURGED BEFORE FINALLY CONNECTING THE APPLIANCE.
The water pipe connections throughout a sealed system must be
capable of sustaining a pressure of up to 3 bar.
Radiator valves must conform to the requirements of
BS.2767(10):1972.
The relief valve drain outlet must be directed away from any
electrical components or where it would cause a hazard to the
user.
A drain cock to BS 2879 must be fitted to the lowest point of the
system.
For circuit design purposes it is important that due note is taken
of the information given in Table 3 relating to the available pump
head.
2.12 SHOWERS, BIDETS, TAPS AND MIXING VALVES
Hot and cold taps and mixing valves used in the system must be
suitable for operating at mains pressure.
Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a
temperature.
Hot and cold mains fed water can be supplied direct to an over-
rim flushing bidet subject to local water company
requirements.
With all mains fed systems the flow of water from the individual
taps will vary with the number of outlets operated
simultaneously and the cold water mains supply pressure to the
property. Flow balancing using ‘Ball-o-Fix’ type valves is
recommended to avoid an excessive reduction in flow to
individual outlets. For further information contact Worcester
Heat Systems Ltd.
2.13 SAFETY CONSIDERATIONS
The appliance must not be operated in a waterless condition.
The appliance must not be operated with the boiler inner casing
cover removed.
Work must not be carried out on the appliance without the gas
and electricity supplies being turned off.
Checks must be made to ensure that the ventilation openings
made into walls and partitions are of the correct size and are not
obstructed.
2.14 OPERATION
See Fig. 1.
Hot Water Mode:
With the appliance in a stand-by condition, i.e. heatbank at the
temperature set by the hot water control thermostat, burner off,
pump off and a demand is made for hot water;
The flow switch will energise the pump and circulate primary hot
water around the boiler and water to water heat exchanger. The
burner will light at its maximum setting to maintain the
temperature of the heatbank.
When hot water is no longer required the appliance will continue
to operate, the burner will cycle a number of times, until the
heatbank has returned to temperature. The pump will continue
to run for about five minutes to disipate the residual heat from
the appliance.
Note: The appliance may be used for Hot Water only before the
Central Heating circuit is connected.
Central Heating Mode:
With the appliance in a stand-by condition and a demand is
made for heating:
The water diverter valve will open, the pump will energise
circulating primary water around the heating system and the
burner will light to the nominal setting pressure.
With the system at the temperature set by the Temperature
Control Knob, on the facia, the burner will cycle to maintain
output to the system.
If the system no longer requires output to maintain the desired
room temperature, the burner will extinguish. The pump will
continue to run for about five minutes to dissipate the residual
heat from the appliance and then switch off.
When the primary water has cooled sufficiently below the
temperature set by the Temperature Control Knob, the burner
will light, pump will energise and the process will be repeated.
Hot Water and Central Heating mode:
The appliance will supply heat to the central heating system as
required. A demand for hot water at a tap or shower will override
the central heating function for the period of the hot water
demand.
When hot water is no longer required the burner and pump will
continue to operate until the heatbank is back to the required
temperature.
The appliance will return to the central heating state and its
normal mode of operation.
4

5
AVAILABLE PUMP HEAD
BOILER OUTPUT HEAD MIN. FLOW RATE TEMPERATURE RISE
ACROSS HEATING
kW Btu/h Metres Feet L/min. Gal/Min. FLOW AND RETURN
8.8 (30,000) 6.1 20.0 11.5 2.5
11.0 (37,000) 5.4 17.5 14.0 3.1
13.0 (44,350) 4.9 16.0 17.0 3.7 11°C (20°F)
HEATING 15.0 (51,200) 4.2 13.5 19.5 4.3
RANGE 17.0 (58,000) 5.3 17.0 15.0 3.3
19.0 (64,800) 4.85 16.0 17.0 3.7 16°C (24°F)
21.0 (71,500) 4.4 14.5 19.0 4.2
23.0 (78,500) 5.2 17.0 16.0 3.5 21°C (38°F)
24.0 (82,000) 5.0 16.5 16.5 3.6
Table 3
DRY WEIGHT OF APPLIANCE 96kg (212lb)
PACKAGED WEIGHT OF APPLIANCE 98kg (216lb)
MAXIMUM INSTALLATION WEIGHT 156kg (344lb)
Table 4: Nominal Weight of Appliance
NOMINAL BOILER RATINGS (10 minutes after lighting the appliance)
MODE OUTPUT INPUT BURNER SETTING GAS RATE
PRESSURE
kW Btu/h kW Btu/h m bar. in. wg. m3/h ft3/h
8.8 (30,000) 11.6 (39,500) 2.2 0.9 1.11 39.2
11.0 (37,000) 14.3 (48,600) 3.2 1.3 1.36 48.0
13.0 (44,350) 16.6 (56,700) 4.4 1.8 1.58 55.5
HEATING 15.0 (51,200) 19.0 (64,850) 5.7 2.3 1.81 63.9
RANGE 17.0 (58,000) 21.4 (72,950) 7.2 2.9 2.04 72.0
19.0 (64,800) 23.8 (81,150) 8.9 3.6 2.27 80.2
21.0 (71,500) 26.2 (89,350) 10.7 4.3 2.50 88.3
23.0 (78,500) 28.6 (97,600) 12.8 5.1 2.73 96.4
24.0 (82,000) 29.8 (101,700) 14.1 5.6 2.84 100.3
HOT WATER 24.0 (82,000) 29.8 (101,700) 14.1 5.6 2.84 100.3
Table 1
FLUE DETAILS
mm inches
WALL HOLE WIDTH 380 15.0
WALL HOLE DEPTH 280 11.0
STANDARD FLUE MINIMUM LENGTH 229 9.0
STANDARD FLUE MAXIMUM LENGTH 407 16.0
EXTENDED FLUE MAXIMUM LENGTH 610 24.0
Table 2: Flue System.
Note: The appliance is factory pre-set to satisfy a central heating requirement of 15 kW (51,200 Btu/h). The output must be adjusted to
suit the heating system when commissioning the appliance.
See Fig. 2 and 3.
The Data Plate is fixed to the top of the control box casing.
3. Technical Data

4.1 THE APPLIANCE MAY BE INSTALLED IN ANY ROOM
ALTHOUGH PARTICULAR ATTENTION IS DRAWN TO THE
REQUIREMENTS OF THE CURRENT I.E.E. WIRING
REGULATIONS AND, IN SCOTLAND, THE ELECTRICAL
PROVISIONS OF THE BUILDING REGULATIONS APPLICABLE IN
SCOTLAND, WITH RESPECT TO THE INSTALLATION OF
APPLIANCES IN ROOMS CONTAINING BATHS OR SHOWERS.
WHERE A ROOM SEALED APPLIANCE IS INSTALLED IN A
ROOM CONTAINING A BATH OR SHOWER, ANY ELECTRICAL
SWITCH OR APPLIANCE CONTROL USING MAINS ELECTRICITY
MUST NOT BE ABLE TO BE TOUCHED BY A PERSON USING THE
BATH OR SHOWER.
4.2 The appliance is not suitable for external installation.
4.3 The appliance is floor standing, the floor must be firm and
level. Special floor protection is not required.
4.4 The floor must be capable of supporting the weight of the
appliance. Refer to Section 3 Table 4.
4.5 If the appliance is to be fitted in a timber framed building
refer to the British Gas publication “Guide for Gas Installations in
Timber Framed Housing”.
4.6 The following clearances must be available for installation
and for servicing. See Fig. 2.
4.7 The appliance can be installed in a cupboard to be used for
airing clothes provided that the requirements of BS 6798 and
BS 5440:2 are strictly followed.
4.8 The airing space must be separated from the boiler space by
a perforated non-combustible partition. Expanded metal or rigid
wire mesh are acceptable provided that the major dimension is
less than 13mm. See BS 6798:1987.
4.9 No combustible surface must be within 75mm of the casing.
See BS476:4.
4.10 The distance between the inner face of a cupboard door
and the cabinet front should not be less than 75mm.
4.11 Always consider the possible need to disconnect the pipes
from the appliance after installation.
4.12 L.P.G. INSTALLATION
The appliance shall not be installed in a room or internal space
below ground level when it is intended for use with L.P.G. This
does not preclude the installation into rooms which are
basements with respect to one side of the building but open to
ground level on the opposite side.
4. Siting The Appliance
6
Installation Service
Above the appliance 450mm 10mm
In front 600mm 600mm
Right side 5mm 5mm
Left side 300mm 5mm
SPECIFICATIONS
CENTRAL HEATING FLOW 22mm Copper Tube
CENTRAL HEATING RETURN 22mm Copper Tube
COLD WATER MAINS INLET 15mm Copper Tube
DOMESTIC HOT WATER OUTLET 22mm Copper Tube
GAS INLET 22mm Copper Tube
PRESSURE RELIEF VALVE DRAIN CONNECTION 22mm Copper Tube
OVERALL CASING HEIGHT 860mm (33.8 in.)
OVERALL CASING WIDTH 600mm (23.6 in.)
OVERALL CASING DEPTH 600mm (23.6 in.)
Table 5:
SPECIFICATIONS
PRIMARY CAPACITY INCLUDING HEATBANK 60 Litres (13.2 galls.)
MAXIMUM INLET DOMESTIC WATER PRESSURE 10 Bar (150 psi)
MINIMUM INLET DOMESTIC WATER PRESSURE (WORKING) 1.0 Bar (15.0 psi)
FOR MAXIMUM HOT WATER FLOW
MINIMUM INLET DOMESTIC WATER PRESSURE (WORKING) 0.1 Bar (1.5 psi)
TO OPERATE THE APPLIANCE
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE Nominally 82°C (180°F)
MAXIMUM STATIC HEAD – PRIMARY 30m (97ft.)
MINIMUM STATIC HEAD – PRIMARY 1.0m (3.3ft.)
OUTPUT TO DOMESTIC HOT WATER 24.0kW (82,000 Btu/h)
OUTPUT TO CENTRAL HEATING 8.8 to 24.0kW (Adjustable)
(30,000 to 82,000 Btu/h)
MAXIMUM DOMESTIC HOT WATER FLOW RATE FROM THE APPLIANCE Nominally 18.0 l/min. ± 15% (3.96 gall/m)
EQUIVALENT HOT WATER FLOW RATE FROM THIS APPLIANCE TO GIVE 20 l/min. (4 gall/m)
30°C RISE (SPECIFIC RATE)
Table 6:

7
600
Duct Width
Flue Position
Rear View Side View
Flue position on
rear of inner
casing
All pipes set in
25mm from rear
of appliance
Appliance
Front
Duct Height
247
572
275
335
550
785
830
120
95
75
25
25
30 ➄
➂
➃
➁
➀
➅
➆
50
115
347
64
Fig. 3. Appliance pipework connections and flue position.
Pipe Connections
1 Central Heating Flow 22mm
2 Central Heating Return 22mm
3 Mains Cold Water In 15mm
4 Hot Water Out 22mm
5 Gas Inlet 22mm
6 Pressure Relief Drain 22mm
7 Open Vent (optional extra) 22mm
1200
Side View Front View
600
910
610
600
Cabinet Depth
600
Cabinet Width
300 5
Space required in front
for installation and
servicing
Space required for
installation
Space required for
servicing
Surface may be
fixed after
installation. A gap
of 10mm is
required above the
appliance
Space required
under fixed
surface
Space required
for installation
Space required
left-hand side
for installation
Space required
each side for
servicing
Floor
Level
450860
1310
Cabinet Height
10
Wall
Fig. 2. Appliance cabinet dimensions and minimum clearances required.

A
G
D
H I
FJ
E
A
B C
G
M
FF
L
L
K
K
5.1 The flue must be installed as specified by BS 5440:Part 1and
the building regulations.
NOTE: Installations coming under the jurisdiction of Building
Control should adhere to the increased clearances.
5.2 TERMINAL POSITION. See Fig. 4.
5.3 The terminal must not cause an obstruction nor the
discharge a nuisance.
5.4 If the terminal is fitted within 850mm of a plastic or painted
gutter or within 450mm of painted eaves then an aluminium
shield at least 750mm long should be fitted to the underside of
the gutter or painted surface.
5.5 If a terminal is fitted less than 2 metres above a surface to
which people have access then a guard must be fitted. Refer to
Section 2, Item 2.9.
5.6 The terminal guard must be evenly spaced about the flue
terminal and fixed to the wall using plated screws
5.7 In certain weather conditions a terminal may steam and
siting where this could cause a nuisance should be avoided.
5.8 Take care to ensure that combustion products do not enter
ventilated roof voids.
6.1 The appliance does not require a separate vent for
combustion air.
6.2 Installations 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 air.
6.3 There must be sufficient clearance around the appliance to
allow proper circulation of ventilation air. Refer to Section 4,
Item 4.6.
6.4 The minimum free areas required are given below.
6.5 Refer to BS 6798 and BS 5440:2 for additional information.
6. Air Supply5. Flue Terminal Position
8
POSITION OF AIR FROM AIR DIRECT
VENTS THE ROOM FROM OUTSIDE
HIGH LEVEL 270 cm2135 cm2
(42 in2) (21 in2)
LOW LEVEL 270 cm2135 cm2
(42 in2) (21 in2)
Fig. 4. Siting of the flue terminal.
MINIMUM SITING DIMENSIONS FOR POSITIONING THE BALANCED
FLUE TERMINAL
TERMINAL POSITION MIN. DISTANCE
A– Directly below an opening, air brick,
window etc. 1500mm (60 in.)
A1– Above an opening, air brick,
window etc. 300mm (12 in.)
A2– Horizontaly to an opening, air brick,
window etc. 600mm (60 in.)
B– Below gutters, soil pipes or drain pipes. 300mm (12 in.)
C– Below eaves. 300mm (12 in.)
D– Below balconies or car port roof. 600mm (24 in.)
E– From vertical drain pipes and soil pipes. 75mm (3 in.)
F– From internal or external corners. 600mm (24 in.)
G– Above ground, roof or balcony level. 300mm (12 in.)
H– From a surface facing a terminal. 600mm (24 in.)
I– From a terminal facing a terminal 600mm (24 in.)
J– From an opening in a car port (e.g. door
window) into dwelling. 1200mm (47 in.)
K– Vertically from a terminal on the same
wall. 1500mm (59 in.)
L– Horizontally from a terminal on the same
wall. 300mm (12 in.)
M– From door, window or air vent (achieve
where possible). 300mm (12 in.)
A1
A2

See Fig. 5. and .6.
7.1 The system must comply with the requirements of BS 6798
and BS 5449:1.
7.2 The appliance must not be operated without the system
being full of water, properly vented and pressurised.
7.3 The safety valve operates at 3bar (45lb/in2). The discharge
must be directed away from electrical items or where it might be
a hazard to the user.
7.4 The pressure gauge indicates the system pressure which
must be maintained.
7.5 The 12 litre expansion vessel is charged to 0.5 bar and is
suitable for a static head of 5m (17.5ft). The pressure can be
increased if the static head is greater than 5m (17.5ft).
7.6 With an initial system pressure of 0.5 bar, a system capacity
of about 104 litres can be accommodated. Refer to BS 7074 Pt 1
for more information.
7.7 The filling point must be at low level. See Fig. 5.
7.8 Water loss must be replaced. See Fig. 6. The connection
should be made in the central heating return as close to the
appliance as possible.
7.9 The make-up vessel must be fitted with a non-return valve.
7.10 Repeated venting loses water from the system. It is
essential that this water is replaced and the system pressure
maintained.
7.11 There must be no connection to the mains water without
the authority of the local Water Company.
7.12 The pump is set at maximum and must not be adjusted.
7.13 Connections in the system must resist a pressure of up to
3 bar.
7.14 Radiator valves must conform to BS 2767(10):1972.
7.15 Other valves used should conform to the requirements of
BS 1010.
7. Sealed System
9
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. 6. System filling and make-up.
Top-up Bottle
Non-Return
Valve
Hot Water
Out
Mains
Cold
Water
Lockshield Valve Radiator Valve
Heating Flow Heating Return
Spherical Plug Ball Valve for
appliance servicing
British Standard Stop
Valve.
Fixed spindle type
Water Main
NOTE: A drain cock should
be installed at the lowest
point of the heating circuit and
beneath the appliance.
Appliance
(Refer to
Fig. 1
for appliance
Water Flow
diagram)
Fig. 5. Sealed primary water system.

See Fig. 7 and 19.
8.1 The appliance is supplied suitable for connection to a sealed
system. If it is to be used with an open vent system then the
instructions given below must be followed.
8.2 A 22mm preformed combined feed and vent pipe available
as an optional extra must be connected to the appliance. See
Section 11.3 and Fig. 19.
Note: Refer to Section 3, Table 5, for the sizes of the flow and
return pipework.
8.3 The feed and expansion cistern should be arranged so that a
minimum static head of 1.0m (3.3 ft) above the top of the
appliance or above the highest point in the heating circuit,
whichever is the highest, is achieved. See Fig. 7.
8.4 The feed and vent pipe must rise continuously from the
appliance to the feed and expansion cistern.
8.5 A safety valve is not required on an open vented system.
With the safety valve left in position then a pipe must be fitted
which terminates such that any discharge does not cause a
hazard to the occupants or damage to electrical components.
8.6 Air within the appliance will be expelled via the feed and
vent connection or dissipated into the rest of the system which
must be fitted with manual air vents at any high points.
8.7 The pump is set to maximum and must not be reset.
8. Open Vent Primary System
10
Hot Water
Out
Mains Cold
Water
Lockshield Valve Radiator Valve
Heating Flow
Heating
Return
22mm dia. Vent Pipe
Circulating Pump
Spherical Plug Ball Valve for
appliance servicing
Combined feed and vent
pipe (22mm).
Must rise continuously.
Disconnect the flexible hose from behind the
circulating pump. The expansion vessel and
flexible hose are not required in the open vent
system and may be discarded. Fit the 22mm
vent pipe supplied as on optional extra.
British Standard Stop Valve.
Fixed spindle type
Water Main
NOTE: A Drain Cock should be
installed at the lowest point of the
heating circuit and beneath the
appliance.
STATIC HEAD (S.H.)
Minimum Static Head 1.0m (3ft). Measured
from the top surface of the appliance or the
highest point in the heating system to the
water level in the feed and expansion tank.
Appliance
(Refer to
Fig. 1 for
appliance
Water Flow
diagram)
Part view showing
Vent Pipe connection
Fig. 7. Open vent water system.
S.H.
9.1 The final 600mm of the mains cold water connection to the
appliance should be made in copper tube only.
9.2 The appliance is suitable for a mains pressure of up to 10 bar
(150 lb/in2).
9.3 The appliance is fitted with a mains supply isolating valve.
9.4 The maximum hot water flow rate is 18 l/min ±15%
(3.9 gall/min).
9.5 In winter, when the mains inlet water temperature is lower a
reduced flow rate, achieved at the tap, will increase the required
delivery temperature.
9.6 It is suggested that long pipe runs to the taps or shower
should be insulated to prevent the rapid cooling of hot water
after the tap or shower has been turned off.
9.7 Hot and cold taps and mixing valves used with this
appliance must be suitable for operating at a pressure of up to
10 bar (150 lb/in2).
9.8 Anti-syphonage arrangements are normally not necessary.
See paragraph 9.10 following.
9.9 Thermostatically controlled or pressure equalising shower valves
will guard against the flow of water at too high a temperature.
9.10 The head of a loose head shower must not fall closer than
25mm (1in) above the top edge of the bath to prevent its immersion
in bath water. Alternatively the shower must be fitted with an anti-
syphonage device at the point of the flexible hose connections.
9.11 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.
9.12 As the maximum temperature of the hot water heat
exchanger is limited by the control circuit, there is normally no need
for water treatment to prevent scale accumulation. In exceptional
circumstances a device to prevent scale formation can be fitted.
9.13 Installation of a scale inhibitor assembly should be in
accordance with the requirements of the local Water Company.
An isolating valve to allow servicing should be fitted.
9.14 The water hardness can be determined using a standard
test paper or by reference to the local water company.
9.15 A miniature expansion vessel (Zilmet R1/2, 160 ml, 15 bar),
available as an optional extra, may be fitted into the domestic
water supply circuit if there is evidence of water hammer.
To fit the expansion vessel:
(i) Remove the front cover. Refer to Section 14 paragraph
14.2 a, and Fig. 16.
(ii) Unscrew the hexagon headed screw located below the
flow switch. See Fig.16.
(iii) Screw the expansion vessel into the connection using
thread sealant compatible with potable water.
9. Domestic Water Supply