Worcester 240 Combi BF User guide

Bosch Thermotechnik
240 Combi BF.
WALL MOUNTED COMBINATION BOILER FOR CENTRAL HEATING
AND MAINS FED DOMESTIC HOT WATER
INSTALLATION AND
SERVICING INSTRUCTIONS
GCNUMBER47 31110
BOILER OUTPUT
Automatic Modulating Control
To Domestic Hot Water and Central Heating
Minimum 9.2 kW (31 ,400 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

Contents
1. Installation Regulations .......... : ..................................... Page 2
2. General Information ...................................................... Page 2
3. Data Technical ................................................................ Page 4
4. Siting the Appliance ...................................................... Page 5
5. Siting the Flue Terminal ................................................ Page 6
6. Air Supply ....................................................................... Page 7
7. Sealed System ................................................................ Page 7
8. Open Vent Primary Water System ............................... Page 8
9. Domestic Hot Water ...................................................... Page 9
·1 . Installation R1egulations
1.1 Gas Safety (Installation and Use) ~egulations 1984
All gas appliances must be installed: by a competent person in
accordance with the above regulations. Failure to install appli·
ances 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 Briti<>h Stnnrl;ml rlnAs nnt, nf itsAlf, r.nn·
fer immunity from legal obligations. In particular the installation
of this appliance must be in accordance with the relevant require·
ments of the Gas Safety (Installation and Use) Regulations 1 984 as
amended, current lEE Wiring Regulations, local Building Regula·
tions, Building Standards (Scotland)(Consolidation) and byelaws of
the local Water Company. Health and Safety Document No. 635
(Electricity at Work Regulations). 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 domes·
tic purposes.
BS 5440:1:1990 Flues and Ventilation for gas appliances of rated
input not
exceeding 60 kW: 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 installa·
tions up to 28 mm (R 1 ).
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 tci those mentioned
in the instructions.
2. General Information
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 domestic hot water and a central
heating
load of up to 16.1 kW.
2.3 The appliance has a permanent pilot.
2.4 PRINCIPLE APPLIANCE COMPONENTS See Fig. 1.
A low thermal capacity Gas to Water heat exchanger.
A Water to Water heat exchanger to provide domestic hot water.
Ft,dly modulating controls in the central heating and domestic
hot water
modes of operation.
An expansion vessel, pressure gauge and pressure relief valve.
Aby-pass for the central heating system.
Temperature safety cut·out controls.
2
10. Electrical ...... , .................................................................. Page 10
11. Installation ..................................................................... Page 14
12. Commissioning .............................................................. Page 17
13. Instructions to the User ................................................ Page 18
14. Inspection and Servicing .............................................. Page 19
15. Replacement of Parts .................................................... Pc;~ge 21
16. Short Parts List .............................................................. Page 28
17. Operational Flow Diagram ............................................ Page 29
18. Fault Finding ................................................................... Page 31
Awater flow regulator.
Astandard horizontal flue assembly giving flue lengths from
229 mm to 420 mm.
An optional extra extension flue kit to provide for flue lengths up
to 559 mm long.
An optional facia mounted programmer instead of the standard
Operating Switch.
2.5 ELECTRICAL SUPPLY
Main5 5upply: 2-1 OV ··, 50 I Iz, 150 wiltts. External fuse 3A.
Internal fuses: T2A (F1) and T315mA (F2).
2.6 GAS SUPPLY
The boiler requires 2.81 m' /h (99.3 ft'/hr) of gas. 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 table below gives an indication of limiting gas pipe
lengths and the allowance to be made for fittings. Refer to
BS6891 for further information.
The meter governor should deliver a dynamic pressure of 20
mbar (Sin wg.) at the appliance.
The complete installation, including the gas meter, must be test-
ed for soundness and purged. Refer to BS 6891 .
TOTAL LENGTH OF
GAS SUPPLY PIPE (metres)
Pipe
Diameter
3 6 9
(mm)
Gas Discharge Rate (m3/h)
2.9
--
15
8.7
5.8 4.6
22
18.0 12.0
9.4 28
Note:
Each fitting used in the gas line from the meter is equivalent to a
length of straight pipe which must be added to the straight pipe
length to give the total length.
ie: Elbow = 0.5 metres, Tee = 0.5 metres, 90° Bend = 0.3 metres.
2.7 PACKING
The appliance and flue components are packed in separate car-
tons.
2.8 GENERAL INSTALLATION
The appliance is supplied for connection to a sealed system but
is suitable for use with an open vent system. The connections
are supplied as an optional kit.
The specified ventilation openings made into a wall or compart-
ment door must not be obstructed.
If the appliance is to be fitted into a compartment then the com-
partment must conform to the requirements of BS 6798: 1987:
Section 6.
Do not place anything on top of the appliance.
The clearances specified for servicing must be maintained.

Fig. 1. Appliance water flow diagram
Waterflow
manifold
[._
Central heating
by-pass adjuster
L__
Automatic air vent
Gas to Water
I h t h
ea exc anger
~-.
---
---
Boiler
I Sealed system
l expansion vessel
~ Circulating pump
Water to Water heat exchanger
tl-r-A#11
~
-c ----- Waterdiverter
r-
valve
14•---~
--l
~
I
I
I
I .
~~ ( ~
Pressure relief val
ve
- Domestic hot water o
ut
-- Mains cold water in
- Central heating return
'
-- Central heating flow
2.9 FLUE
The appliance has a room-sealed balanced flue system to the
rear.
The standard flue assembly length is from 240 mm to 420 mm.
An extention flue length from 420 mm to 559 mm is available.
A terminal guard, Type GC 393 545, is available from Tower Flue
Components, Vale Rise, Tonbridge, TN9 1 TB.
Do not allow the flue terminal fitted to the outside wall to
become obstructed or damaged.
2.1 0 CONTROLS
The electronic control system and gas valve modulate the heat
input in response to the central heating and domestic hot water
temperature settings between minimum and maximum.
The Operating Switch provides for the selection of domestic hot
water only (WATER) or central heating and domestic hot water
(HEATING & WATER) or OFF.
A facia mounted programmer is available as an optional extra. A
remote mounted programmer may be connected to the appli·
ance.
The integral facia displays indicate the status of the appliance.
There is provision for the connection of a mains voltage room
thermostat and/ or a frost thermostat.
The electronic controls prevent rapid cycling of the appliance in
the central heating mode.
3
2.11 SYSTEM NOTES
WARNING
Check that no dirt is left in either the gas and water pipework
as this could cause damage to the appliance. Thoroughly flush
the heating system and the cold water mains supply. Purge
the gas supply before finally connecting the appliance ..
The water pipe connections throughout a sealed system must
be capable of sustaining a pressure of upto 3 bar.
Radiator valves must conform to the requirements of BS2767
(10): 1972.
The relief valve discharge must be directed away from any elec·
trical 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 a mains pressure of up to 10 bar.
Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a temper·
ature.
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 simultane·
ously 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 or even starvation to indi·
vidual outlets. For further information contact Worcester Heat
Systems Ltd.
2.13 SAFETY CONSIDERATIONS
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 switched 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
Domestic Hot Water: With a demand for hot water the burner
will light at its maximum setting and then automatically adjust
its output to maintain the temperature rise of the delivered
water. When hot water is no longer required, the burner will
extinguish. The pump will continue to run for a short period to
dissipate the residual heat from the appliance.
Central Heating: With a demand for heating the burner will
light at its minimum setting and gradually increase to give the
maximum output. The output of the appliance is then
automatically adjusted
to maintain the temperature of the
system. The output can reduce down to a minimum of 9.2 kW. If
the system no longer requires even the minimum output to
maintain the desired room temperature the burner will
extinguish. The pump will continue to run to dissipate the
residual heat from the appliance. The appliance will remain off
for a fixed period of two minutes before re-lighting to
automatically meet the system requirements.
Domestic Hot Water and Central Heating: The appliance will
supply heat to the central heating system as required. A
demand
for domestic hot water at a tap or shower will override
the central heating requirement for the period of the domestic
hot water demand. When hot water is no longer required the
burner will extinguish and the appliance will return to the cen-
tral heating state and its normal mode of operation. The pump
will continue to run to dissipate the residual heat from the appli·
ance as necessary.

3. Technical Data
The Data Plate is fixed to the control box casing.
TABLE 1
TABLE 2 - Flue Details
NOMINAL BOILER RATINGS
mm inches
Output Input
Burner Setting
Gas Rate
Pressure
Wall Hole Size
Width 365 14.4
kW Btu/h
kW
Btu/h mbar. in.wg. m
3
!h
tt
3
!h
9.2
31,400
12.6
43,000 3.0
1.2 1.22
43.0
24.0
82,000
30.0
102,400 14.7
5.9 2.81
99.3
Height 265 10.5
Standard Flue -Minimum Length 240 9.5
Standard
Flue -Maximum Length 420 16.5
Extended
Flue -Maximum Length 559 22
TABLE3
AVAILABLE PUMP HEAD
Boiler Output Head Min. Flow Rate
Temp. rise across
Btu/h feet litres/min
gal/min
heating flow
kW
metres
and return
9.2
31,400 4.9 15.9 12.0
2.64
11 °( (20°F)
24.0
82,000
2.0 6.5
22.0
4.81
15"C (28°F)
TABLE4
SPECIFICATIONS
CENTRAL HEATING FLOW FITTING 22 mm Compression
CENTRAL HEATING RETURN FITTING 22 mm Compression
COLD WATER MAINS INLET FITTING 15 mm Compression
DOMESTIC HOT WATER OUTLET FITTING . 15 mm Compression
4VA1i.;A!ibi t~UMI~ i-l£1it) l
-~"*''!1""m~ ....... -"'....-.:., ... w·~. ""'""'/,.,.;...,.;.w.1f ....... r· """""Mi·vf'o.·.""1-W'r-~;.,....,!'-."~: Mt ....... tfi'""'~'l"''l-}~~
·· 1..~1 ~r 1ju · ·ut . :m~· . i ltl: Fitiw ~t~ . 1HfiJf:ji~ ~.~ i,(;(~si!
PKt:SSU~E Kt:d£YVALVt. u:l:J\RGEtrl'l~J.\11 """"''"d:,,,
1 !:l mm LompressiOn
CASING HEIGHT 900 mm (35.4 in.)
CASING WIDTH 450 mm (17.7 in.)
CASING DEPTH
360 mm (14.2 in.)
WEIGHT (including water) 48.7
kg (107lb.)
INSTALLATION WEIGHT
~
46.5 kg (1 02 lb.)
"
PACKAGED WEIGHT 49.6 kg (1 09lb.)
TABLE 5
SPECIFICATIONS
PRIMARY WATER CAPACITY
2.7litres (0.6 galls.)
MAXIMUM COLD SUPPLY PRESSURE
10 Bar (150 psi)
MINIMUM COLD SUPPLY PRESSURE (WORKING) FOR MAXIMUM HOT WATER FLOW
1.6 Bar (23.5 psi)
MINIMUM COLD SUPPLY PRESSURE (WORKING) TO OPERATE THE APPLIANCE
0.6 Bar (9 psi)
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE
Nominally 82°C (180°F)
MAXIMUM STATIC HEAD (PRIMARY)
25 metres (81 ft)
MIMIMUM STATIC HEAD (PRIMARY)
0.3 metres (1 ft)
OUTPUT TO DOMESTIC HOT WATER
Modulating 9.2-24 kW
(31 ,400-82,000 Btu/h)
OUTPUT TO CENTRAL HEATING
Modulating 9.2-24 kW
(31 ,400-82,000 Btu/h)
MAXIMUM DOMESTIC HOT WATER FLOW RATE FROM THE APPLIANCE
Nominally 8.5 litres/min (±15%)
(1 .87 gallons/min)
EQUIVALENT DOMESTIC HOT WATER FLOW RATE TO GIVE A TEMPERATURE RISE OF 35°C Nominally 9.8litres/min
(2.16 gallons/min)
4

4. Siting The Appliance
4.1 The appliance may be installed in any room although par·
ticular attention is drawn to the requirements of the current
I.E.E. Wiring Regulations and, in Scotland, the electrical provi·
sions 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 contain·
ing 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 does not require any special wall protection.
4.4 The wall must be capable of supporting the weight of the
appliance. See 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.
Installation
Servicing
Above
100mm 100mm
In front
600mm 600mm
Below 230mm 230mm
Right hand side
5mm
5mm
Left hand side
5mm
Smm
4.7 The appliance can be installed in a cupboard 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 13 mm. See BS 6798:1987.
4.9 No combustible surface must be within 75 mm of the cas-
ing. See BS476:4.
4.1 0 The distance between the inner face of a cupboard door
and the cabinet front should not be less than 75 mm.
4.11 Always consider the possible need to disconnect the pipes
from the appliance after installation.
Fig. 2. Appliance casing dimensions and required clearances.
600mm
Space required in front
SIDE VIEW
for installation and servicing.
I
I
360 mm 1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
--------------
I
I
I
I
I
I
I
I
FRONT VIEW
450mm
Fixing holes
1
r-- 413 mm CRS. _, 1
I ~-~0~:--f _________ _j I II
li I!
,-fl
.a_Lf,:
900m
~ 1 Space required below 5 mm i 1I
/). 1 for installation and servicing. Space required at left hand side -+t ~-+- . -.r ~
/) ________ ._j t for installation and servicing. !L ______________ _j l
Smm
m
Space required at right hand side
for installation and servicing.
5

Fig. 3. Appliance pipework connections.
,_ ...
·ao· :e-···.
- ii ::,..:;;.r -
-·
Central heating flow -+--""'
Central heating return
Mains cold water in --It+---
Pressure relief valve discharge .......j.---------- 306 mm --~
• I \'
. .
_, TIW!M.T\1111-
l_l ~ mm All~""""
Gas cock ---------405mm --------1~
5. Siting the Flue Terminal
See Fig. 4
5.1 The flue must be installed as specified in BS 5440:Part 1.
5.2 The terminal must not cause an obstruction nor the dis-
charge cause a nuisance.
5.3 Ifthe terminal is fitted within 850 mm of a plastic or painted
gutter
or within 450 mm of painted eaves then an aluminium
shield at least 750 mm long should be fitted to the underside of
the gutter or painted surface.
5.4 If a terminal is fitted less than 2 metres above a surface to
which people have access then a guard must be fitted. See Sec-
tion 2.9.
Fig. 4. Siting of the flue terminal.
MINIMUM SITING DIMENSIONS FOR POSITIONING THE BALANCED
FLUE TERMINAL.
A
6
5.5 The terminal guard must be evenly spaced about the flue
terminal and fixed to the wall using plated screws
5.6 In certain weather conditions a terminal may steam and sit-
ing where this could cause a nuisance should be avoided.
5.7 Take care to ensure that combustion product:; do not enter
ventilated roof voids.
TERMINAL POSffiON MIN. DISTANCE
A- Directly below an openable window or
other opening e.g. air brtck
300 mm (12in.)
B- Below gutters, soil pipes or drain pipes
300 mm (12in.)
c- Below eaves
300 mm (12in.)
D-Below balconies or car port roof 600 mm (24in.)
E- From vertical drain pipes and soil pipes
75mm(3in.)
F- From internal or external corners
600 mm (24in.)
G-- Above ground, roof or balcony level
300 mm (12in.)
H-From a surface facing a terminal 600 mm (24ln.)
I- From a terminal facing a terminal 600 mm (24ln.)
J- From an opening in a car port (e.g. door
window) Into dwelling 1200 mm (47in.)
K- Vertically from a terminal on the same wall
1500 mm (59in.)
L- Horizontally from a terminal on the same
wall
300 mm (12ln.)
M-From door, windoworairvent(achieve
where possible)
300 mm (12in.)

6. Air Supply
6.1 The appliance does not require a separate vent for combus-
tion air.
6.2 Installations in cupboards or compartments require perma·
nent 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. The clearances required
7. Sealed System
See Figs. 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 Tht:! pressure relief valve operates at 3bar (45lb/in2 ). The dis-
charge must be directed away from electrical components 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 10 litre expansion vessel is charged to 0.5 bar and is
suitable for a static head of 5 metres (17 .Sft). The pressure can
be increased if the static head is greater than 5 metres (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 707 4 Pt. 1
for more information. The charge pressure can be increased but
with a decrease in system volume.
Fig. 5. Sealed primary water system.
lockshield valve. Radiator valve.
lllllllll J 11111111
Note. A drain cock should be installed at
the lowest point of the heating circuk and
beneath the appliance.
7
for Installation and Servicing will normally be adequate for venti·
lation. See Section 4.6.
6.4 The minimum free areas required are given below.
Position of
Air from
Air direct
airvents the room
from outside
High Level
270 cm
2•
135 cm
2•
(42in2 .)
(21 in
2)
Low Level
270cm2•
135 cm
2•
(42in2 .)
(21 in
2
.)
6.5 Refer to BS 6798 and BS 5440:2 for additional information.
7.7 The filling point must be at low level. See Figs. 5 and 6.
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. See Figs. 5 af)d 6
7.9
The make-up vessel must be fitted with a non-return valve.
7.1 0 Repeated venting loses water from the system. It is essen-
tial that this water is replaced and the system pressure main·
tained.
7.11 Connections to the mains water supply must not be made
without the authority of the local Water Company.
7. 12 The pump is set at maximum and must not be adjusted.
7.1 3 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.
7.16 To make use of the extra heating available from the appli·
ance at the end of any demand, it is recommended that a single
small radiator be left permanently open.
Sealed system
--expansion vessel
-· Water to Water
heat exchanger
Central heating
by-pass adjuster- '+t--T"H--'
Fill point-----'
Heating return
Heating flow.
Domestic hot water out
t
I
l
Note. The mains cold inlet
connection to the appliance
must come before any other
connection from the cold supply.
Domestic
coldwater.
_.. British Standard
stop valve.
Fixed spindle type.
+- Water main.

Fig. 6. System filling and make-up.
Heating Return
Non return
valve
+-
Worcester Combi-Fill System
Non return
va-4!- ~ Hose union
1
1-----t..•--.f .... lll-..;...===:u ~=· •• ~ +-
!! !! Stop cock
u ,.
Test cock \l,m,;~
Temporary hose
8. Open Vent Primary Water System
See Fig. 7
8.1 The size of the flow and return pipework is given in Section
3 - Table 4. The components required to connect the appliance
to an open vent system are available as an optional extra kit.
8.2 The feed and expansion cistern should be arranged so that
there is a minimum static head of 0.3 metres (12in.) above the
top of the appliance or above the highest point in the heating
circuit, whichever is the higher. See Fig. 7.
8.3 The feed and vent pipe should be 22 mm diameter and rise
continuously from the appliance to the feed and expansion cis-
tern.
Fig. 7. Open vent water system.
S.H.-Minimum static head 300 mm 112 in. I
measured from the top surface of the
appliance or highest point in the heating
system to the water level in the feed and
expansion tank.
Feed and expansion tank
lockshield valve. Radiator valve.
lllllllll J
11111111
Note. A drain cock should be installed at
the lowest point of the heating circuit and
beneath the appliance.
8
Heating Return
Auto
air vent
1- .... 1-- Fill Point
' Heating Return
300mm (12inl min.
above the highest
point of the system.
8.4 A pressure relief Viilve is not required on an open vented sys·
tem. If the pressure relief valve is left in position then a discharge
pipe must be fitted which terminates in a position such that any
water or steam discharge does not cause a hazard to the occu-
pants or damage electrical components.
8.5 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 point.
8.6 The pump is set to maximum and must not be reset.
8.7 To make use of the extra heating available from the appli·
ance at the end of any demand, it is recommended that a single
small radiator be left permanently open.
Central heating
Sealed system
--expansion vessel
--Water to Water
heat exchanger
by-pass adjuster -'"l'f+---!-+--1---l
Fill point ---- .J
Heating return
Heating flow.
Domestic hot water out
I
Note. The mains cold inlet
connection to the appliance
must come before any other
connection from the cold supply.
Domestic
cold water.
,.. British Standard
stop valve.
Fixed spindle type.
-Water main.

9. Domestic Hot Water
9.1 The following are general requirements and, if necessary,
reference should be made to the local Water Company before
fitting the appliance.
9.2 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 connection
point (Rc'h) is provided adjacent to the flow switch within the
appliance.
A Zilmet Z160 expansion vessel is the preferred type. Athread
sealant compatible
with potable water must be used.
9.3 The final 600 mm of the mains cold water connection to the
appliance should be made in copper tube only.
9.4 The appliance is suitable for a mains pressure of up to 10
bar (150 lb/in').
9.5 The appliance is fitted with a mains supply isolating valve.
9.6 The maximum domestic hot water flow rate is 8.5
litres/min. (
± 15%) (1.87 gallons/min.).
9.7 In winter (when the mains inlet water temperature is lower)
a reduced flow rate at the taps will be required to achieve the
maximum hot water delivery temperature available in warmer
weather.
9.8 It is a requirement that long pipe runs to the taps or shower
should be insulated to prevent the rapid cooling of domestic hot
water after a tap or shower has been turned off. Refer to
BS5546: 1990.
9
9.9 Hot and cold taps and mixing valves used with this appli·
ance must be suitable for operating at a pressure of up to 10 bar
(1 SO lb/in').
9.10 No anti·syphonage arrangements are necessary except for
some loose head showers. See also Section 9.11 following.
9.11 Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a temper·
ature.
9.12 The head of a loose head shower must not fall closer than
25 mm (1 in.) above the top edge of the bath to prevent its
immersion in bath water. Alternatively the shower must be fit·
ted with an anti·syphonage device at the point of the flexible
hose connections.
9.13 The supply of hot and cold mains water direct to a bidet is
permitted, (subject to local Water Company requirements), pro·
vided 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 nee·
essary.
9.14 AS the maximum temperature of the Water to 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.
Installation of a scale inhibitor assembly should be in accor·
dance with the requirements of the local Water Company. An
isolating valve should be fitted to allow servicing. The water
hardness
can be determined using a standard test paper or by
reference to the local Water Company.

10. Electrical
See Figs. 8, 9,10,11 and 12.
1 0. 1MAINS SUPPLY. 240 V - , SO Hz, 1 SO watts.
External Fuse 3A. Internal Fuses: T2A (F1) and T31 SmA (F2).
10.2 It must be possible to completely isolate the appliance.
1 0.3 Connection to the mains supply should be via a double
pole isolator with a contact separation of 3mm in aU poles and
supplying the appliance and controls only.
1 0.4 The appliance must be earthed.
1 0.5 Mains Cable. 0. 7S mm• (24 x 0.20 mm) to BS 6SOO Thble
16.
If a new cable is needed it must be connected into the terminals
marked L (Brown or Red lead), N (Blue or Black lead) and ;!<-
(Green/Yellow or Green) and be held securely in the cable clamp.
For access refer to Section 14. NOTE: Ensure the earth lead is
longer than the live and neutral leads.
10.6 The wiring between the appliance and the electrical supply
shall comply with current lEE Wiring Regulations and any local
regulations which apply.
10.7 If a room and/or frost thermostat is to be fitted refer to
Figs. 11 and 12. The thermostats must be suitable for use on
mains voltage.
1 0.8 A facia mounted programmer is available as an extra.
Instructions
are supplied with the programmer kit.
10.9 A time switch or programmer can be fitted externally to the
appliance.
10.10 SAFETY CHECK. After installation or in the event of an
electrical fault the electrical system shall be checked for short
circuits,
fuse failure, incorrect polarity of connections, earth
continuity and resistance to earth.
Fig. 8. Wiring Diagram - Control panel and facia.
(All components shown viewed from front of appliance)
A
TO
GAS VALVE
MAIN
~Fr:w~ fj-m~------- -----1
br e3X OX11 ~ 1
• • 410 3
F2 FUSE I
br1]1 4 I
bl
0
2X8 MAIN DRIVER BOARD I
r----;C;y 3 fiFt I
br : 1L tj FUSE
1
~:
bl I 2NX7 X1 v
• 3E 2 pk
I 4E X5 X4 X3 X2 3 I v
112 31 2312345123 4581234 5 81
gvt~rn!9J11~!tr1Jr~!ttr.r~r.r~
~ 'i~tVV%-J ~~~
~ ~ in I ;_ .:.: ~~ .. :.. ---'
OVERRUN ~ Iii DIVERTER H£ATING HOT WAml MODUREG
THERMOSTAT i j! VALVE SENSOR msOR REGULATOR
12 12 MICRO·SWITCH
MAINS
COLOUR CODE
br-brown bl-blue gy-green and yellow bk-black or-orange
r-red w-white y-yellow g-grey v-violet pk-pink
10