Worcester WR 325 BF User guide

Bosch Thermotechnik
INSTALLATION AND
SERVICING INSTRUCTIONS
WR 325 BF
Gas Fired Multi oint
Water Heater
This appliance conforms to European Standard EN 26.
It is the law that all gas appliances are installed by competent persons.
The following instructions should be read carefully as the manufacturer cannot be held
responsible for any damage to property, persons or animals caused by incorrect installation
or operation of the appliance.
It is recommended that the appliance be serviced annually by a competent person or the
local as Region.
The Users Instructions should be handed to the user and the function and operation of the
appliance explained.
For your safety – if you smell gas: 3. Do not operate any electrical switches
1. Turn off the appliance 4. Extinguish all naked flames
2. Open all windows and doors 5. Contact the local as Region immediately
GC NUMBER 52 311 01

1.1 as Safety (Installation and Use) Regulations 1984:- 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 manufacturer’s 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 as Safety (Installation and Use)
Regulations 1984 (as amended), 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). 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 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 60 kW: Flues.
BS 5440:2:1989 Flues and ventilation for gas appliances of rated
input not exceeding 60 kW: Air Supply.
BS 6891:1988 Installation of low pressure gas pipework
installations up to 28 mm (R1).
1. 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.
2.1 This appliance is available for use with natural gas.
When installing the appliance for use with natural gas, please
check 10 digit number on carton to ensure that the correct
appliance has been specified. The 10 digit number for a natural
gas appliance is 7 702 340 006.
2.2 This appliance is available for use with LP .
When installing the appliance for use with LP , please check 10
digit number on carton to ensure that the correct appliance has
been specified.
The 10 digit number for an LP appliance is 7 702 440 007.
2.3 This appliance is not suitable for external installation.
2. The appliance is set to provide a maximum output of 21.4
kW and a minimum output of 7 kW.
2.5 The appliance has a permanent pilot.
2. General Information
1. Installation Regulations
1. Installation Regulations.................................................Page 2
2. eneral Information ......................................................Page 2
3. Technical Data ................................................................Page 5
4. Siting the Appliance ......................................................Page 5
3. Siting the Flue Terminal ........................ ........................Page 5
6. Air Supply .......................................................................Page 6
7. as Supply ..................................... ................................Page 6
8. Installation ................ .....................................................Page 6
9. Commissioning ..............................................................Page 7
10. Inspection and Servicing ..............................................Page 8
11. Replacement of Parts ....................................................Page 9
12. Fault Finding ....................... ...........................................Page 10
13. Short Parts List ...................... ........................................Page 10
2.6 PRINCIPLE APPLIANCE COMPONENTS
A low thermal capacity as to Water heat exchanger.
A stainless steel main gas burner.
A gas section.
A water section.
A thermoelectric safety valve.
2.7 PACKING
The appliance and flue components are packed in separate
cartons.
2.8 GENERAL INSTALLATION
If the appliance is to be fitted into a compartment, the
compartment must conform to the requirements of BS
6798:1987: Section 6.
The specified ventilation openings made into a wall or
compartment door must not be obstructed.
Do not place anything on top of the appliance.
The clearances specified for servicing must be maintained.
2.9 FLUE
The appliance has a room-sealed balanced flue system to the
rear.
The standard flue assembly will accommodate a wall thickness
of between 260 mm and 430 mm. The 10 digit code number for
the standard flue assembly is 7 709 000 423.
A short flue assembly is available and will accommodate a wall
thickness of between 100 mm and 150 mm. The 10 digit code
number for the short flue assembly is 7 709 000 425.
An extended flue assembly is available and will accommodate a
wall thickness of between 410 mm and 570 mm. The 10 digit
code number for the extended flue assembly is 7 709 000 424.
2.10 FACILITY TO FIT A SPOUT AND INTEGRAL TAP KIT
The appliance has the facility for a spout and integral tap kit to
be fitted for oversink installation. If this type of installation is
required, please order the following components as necessary:
Integral tap kit
(incorporating hot and cold taps and handles) 7 709 000 406
Chrome plated swivel spout – 150 mm length 7 709 000 041
Chrome plated swivel spout – 250 mm length 7 709 000 042
Chrome plated swivel spout – 350 mm length 7 709 000 043
2
Contents

Fig. 1. Appliance water flow diagram
1. Heat exchanger
2. Pilot gas pipe
3. Gas injector nozzle
4. Measuring point
6. Valve spring
7. Large gas valve
8. Pilot gas filter
9. Pilot gas valve
10. Main gas valve
11. Pilot gas valve stem
12. Pilot gas button
13. Gas control slide
14. Piezo igniter
15. Gas filter
16. Magnetic unit
17. Slow-ignition valve
18. Venturi
19. Measuring point
20. Gas inlet
21. Water strainer
22. Hot water connecting pipe
23. Cold water connecting pipe
24. Volumetric water governor
25. Water flow selector
26. Relief valve
27. Correcting screw for minimum
water flow
28. Diaphragm
29. Blow-off valve
3
KEY TO COMPONENTS

Fig. 2. Appliance components
KEY TO COMPONENTS
1. Heat exchanger 30. Flue hood
2. Pilot gas pipe 31. Combustion chamber seal
13. Gas control slide 32. Main gas burner
14. Piezo igniter 33. Pilot assembly
*20. Gas inlet – downward facing 34. Drain valve
22. Hot water connecting pipe –rear facing, left-hand side 35. Gas section
23. Cold water connecting pipe –rear facing, right-hand side 36. Water section
25. Water flow selector
*The gas inlet is situated towards the rear of the appliance.
Do not confuse with the spout connection which is part of the brass housing.

TABLE 1 – GENERAL
3. Technical Data
TABLE 2 – FLUE DETAILS
TABLE 3 – PERFORMANCE
.1 The appliance may be installed in any room which has an
appropriate outside wall.
.2 The appliance is not suitable for external installation.
.3 The appliance does not require any special wall protection.
. The wall must be capable of supporting the weight of the
appliance. See Technical Data – Table 1.
.5 If the appliance is to be fitted in a timber framed building,
refer to the British as Publication “ uide for gas installations in
timber framed housing”.
.6 The following clearances must be available for installation
and for servicing:
. Siting the Appliance .9 No combustible surface must be within 75 mm of the casing.
See BS 476:4.
.10 The distance between the inner face of a cupboard door
and the cabinet front should not be less than 75 mm.
Natural Gas LPG
Minimum rated output 7 kW 7 kW
Maximum rated output 21.4 kW 21.4 kW
Rated input 25.5 kW 25.5 kW
as rate (maximum) 2.7 m3/hr 2.0 m3/hr
Number of injectors 14 14
Injector diameter 1.10 mm 0.74 mm
Pilot injector marking 5 49
Burner pressure 17 mbar 27 mbar
Height 755 mm 755 mm
Width 400 mm 400 mm
Depth 220 mm 220 mm
Dry weight 16 kg 16 kg
as connection Rc 1
/2Rc 1 /2
Hot/cold water connections 15 mm copper 15 mm copper
Wall hole size – width 224 mm (9 in.)
Wall hole size – height 326 mm (13 in.)
Standard flue – minimum length 260 mm (10.4 in.)
Standard flue – maximum length 430 mm (17.2 in.)
Short flue – minimum length 100 mm (4 in.)
Short flue – maximum length 150 mm (6 in.)
Extended flue – minimum length 410 mm (16.4 in.)
Extended flue – maximum length 570 mm (22.8 in.)
Maximum cold water supply inlet pressure 12 bar (180 p.s.i.)
Minimum cold water supply inlet pressure to operate the appliance 0.1 bar (1.5 p.s.i.)
Minimum cold water supply inlet pressure for maximum domestic hot water flow 1.0 bar (15 p.s.i.)
Domestic hot water delivery with temperature control knob fully anticlockwise 4 to 12.3 litres/minute at
25°C temperature rise
Domestic hot water delivery with temperature control knob fully clockwise 2 to 6.1 litres/minute at
50°C temperature rise
See Fig. 3.
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
discharge cause a nuisance.
5.3 If the 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. If a terminal is fitted less than 2 metres above a surface to
which people have access then a guard must be fitted.
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
siting where this could cause a nuisance should be avoided.
5.7 Take care to ensure that combustion products do not enter
ventilated roof voids.
5. Siting the Flue Terminal
.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.
.8 The airing space must be separated from the appliance
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.
Above 50 mm
In front 600 mm
Below 150 mm
Right hand side 10 mm
Left hand side 10 mm
5

A
G
D
H I
F
J
E
A
B C
G
M
F
F
L
L
K
K
Fig. 3. Siting of the flue terminal.
MINIMUM SITIN DIMENSIONS FOR POSITIONIN THE BALANCED
FLUE TERMINAL
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. The clearances
required for installation and servicing will normally be adequate
for ventilation.
6. The minimum free areas required are given below.
6. Air Supply TOTAL LENGTH OF
GAS SUPPLY PIPE (metres)
369
Gas Discharge Rate (m3/h)
2.9 – – 15
8.7 5.8 4.6 22
18.0 12.0 9.4 28
Pipe
Diameter
(mm)
Position of Air from Air direct
air vents the room from outside
High Level 270 cm2. 135 cm2.
(42 in2.) (21 in2)
Low Level 270 cm2.135 cm2.
(42 in2.) (21 in2.)
6.5 Refer to BS 6798 and BS 5440:2 for additional information.
The appliance requires 2.7 m3/hr (95.4 ft3/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 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 (8 in w.g.) at the appliance.
The complete installation, including the gas meter, must be
tested for soundness and purged. Refer to BS 6891.
A gas service cock must be fitted before each appliance, a gas
service cock is supplied with every natural gas appliance (not
supplied with LP model).
Important: If the 2.7m3/hr gas rate to the appliance cannot be
reached, the specified hot water conditions will not be achieved.
This could result in customer complaints. Always ensure that the
gas supply is adequate.
7. Gas Supply
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.
i.e. Elbow=0.5 metres, Tee=0.5 metres, 90˚ bend=0.3 metres.
The installation must be carried out by competent persons.
On delivery, check to make sure that the packaging has not been
damaged. If there is evidence of damage, contact your supplier
immediately.
Check the 10 digit code number on the appliance carton to
ensure that the correct appliance for the gas supply has been
supplied.
The code number for a natural gas appliance is 7 702 340 006.
The code number for an LP appliance is 7 702 440 007.
Before commencing work, check that the correct flue kit has
been supplied. There are three different telescopic flue kits
available for various wall thicknesses.
(See Technical Data – Table 2)
8.1 FLUE KIT INSTALLATION
Refer to flue kit installation instructions which are packed inside
the flue kit carton.
8.2 APPLIANCE INSTALLATION
(a) Unpack the appliance and take care to remove the installation
kit which is packed on top of the polystyrene packing.
The installation kit consists of the following:
One gas service cock (not supplied with LP model)
One cold water isolating cock complete with fibre washer
One hot water outlet complete with fibre washer
Two 15 mm x 1
/2 in. BSP female copper compression fittings
8. Installation
6
TERMINAL POSITION MIN. DISTANCE
A– directly below an openable window or
other opening e.g. air brick. 300 mm (12 in.)
B– Below gutters, soil pipes or drain pipes. 300 mm (12 in.)
C– Below eaves. 300 mm (12 in.)
D– Below balconies or car port roof. 600 mm (24 in.)
E– From vertical drain pipes and soil pipes. 75 mm (3 in.)
F– From internal or external corners. 600 mm (24 in.)
– Above ground, roof or balcony level. 300 mm (12 in.)
H– From a surface facing a terminal. 600 mm (24 in.)
I– From a terminal facing a terminal 600 mm (24 in.)
J– From an opening in a car port (e.g. door
window) into dwelling. 1200 mm (47 in.)
K– Vertically from a terminal on the same
wall. 1500 mm (60 in.)
L– Horizontally from a terminal on the same
wall. 300 mm (12 in.)
M– From door, window or air vent (achieve
where possible). 300 mm (12 in.)
  

(b) Lay the appliance on its back and pull off the Temperature
Control Knob.
(c) Unscrew the plastic Temperature Control Knob housing.
(d) Remove the four casing screw covers. Take out the four
casing fixing screws and lift the casing clear.
(e) Remove the collector hood from the appliance by slackening
the two fixing screws and lifting the hood clear.
(f) Lift the appliance on to the two mounting studs which are
part of the flue kit assembly and fix in position using the two
slotted nuts supplied.
If required, there are fixing holes situated on the appliance back
plate. Mark the fixing hole positions on the wall. Remove the
appliance. Drill and plug the wall and then re-fit the appliance.
(g) Push the flue gas connecting duct into the flue duct stub in
the balanced flue assembly making sure it is fully home and
resting against the stop protruding from the base of the stub
duct. Ensure flue gas connecting duct has been cut to the correct
size. See the Flue Kit Installation Instructions.
(h) Re-fit the collector hood making sure that the flue duct spigot
on the collector hood enters the flue duct connector. Tighten the
two collector hood fixing screws. Connect the gas supply pipe to
the appliance via a gas service cock.
Note: The whole of the gas installation should be inspected and
tested for soundness and purged in accordance with the
recommendations of BS 6891.
(i) Fit the two chrome water fittings supplied using fibre washers.
The fitting which includes the stop valve should be fitted onto
the rear right hand connection (viewed from the front) and the
other fitting onto the rear left hand connection (viewed from the
front).
(j) Fit the two copper tails supplied to the chrome water fittings
using a jointing compound suitable for use with potable water.
(k) Connect the appliance to the incoming cold water supply via
the fitting which includes the stop valve.
(l) Connect the appliance to the domestic hot water remote draw
off points via the other fitting.
(m) At the bottom centre of the water section assembly there is
an additional 1
/2 in. male threaded joint which is the connecting
thread for when a spout is connected for an oversink installation.
See eneral Information paragraph 2.10.
This outlet will not pass water until such time as an integral tap
kit is installed on to the appliance and therefore, in a normal
remote draw off installation, the 1
/2 in. male threaded joint
should be left unconnected and unplugged.
(n) Turn on the water supply to the appliance. Open the stop
valve on the inlet fitting to the appliance and then open the
highest hot water tap in the installation.
Allow water to pass in order to vent the system of air. Close the
tap.
Before commissioning the appliance, the whole gas installation
must be purged and tested for gas soundness in accordance with
the current edition of BS 6891.
Important: Open all doors and windows. Extinguish naked lights
and do not smoke while purging the gas line.
(a) Ensure that the gas service cock in the gas inlet pipe is
turned off.
(b) Loosen screw Aand connect a pressure gauge to the test
point. See Fig. 4.
(c) Turn on the gas service cock.
(d) Move the gas control slide to the ignition position. See Fig. 5.
Observe the pilot burner through the observation window. Press
in the centre button of the control slide and hold depressed while
pushing in the Piezo igniter button two or three times. The pilot
9. Commissioning
Fig. . Inlet pressure test point
7
Fig. 5. Gas control slide – ignition position
Fig. 6. Gas control slide – operating position
Piezo igniter
Front
Gas control slide in this position
Piezo igniter
Gas control slide in this position
should light. Wait 20 seconds and then release the centre button
of the control slide.
The pilot should remain alight. If the pilot is not established,
repeat the operations until a flame is established.
Note: On initial light up, or after prolonged shut-down, the
establishment of the pilot may take several attempts due to the
presence of air in the gas supply pipe.
The pilot flame should envelope approximately 5 mm of the
thermocouple head.
(e) Move the control slide fully to the right. See Fig. 6. Fully open
any hot water tap. The main burner should light.
(f) Check the dynamic inlet gas pressure. The pressure for natural
gas should be 20 mbar and the pressure for LP should be 37
mbar.

If the pressure is not correct then check the gas supply to the
appliance.
If the pressure is correct, turn off the hot water tap and move the
control slide to the off position. See Fig. 7.
Turn off the gas service cock. Remove the pressure gauge and
tighten screw A. See Fig. 4.
(g) Loosen screw Dand connect a pressure gauge to the test
point. See Fig. 8.
Re-light the appliance as described in paragraph 9 ( d and e).
(h) Operate the appliance for at least 2 minutes then check that
the burner pressure is as stated in Technical Data – Table 1.
(i) Turn off the hot water tap. Close the gas service cock. Remove
the pressure gauge and tighten screw D.
(j) Re-fit the appliance casing using the four fixing screws. Fit the
plastic Temperature Control Knob housing. Fit the Temperature
Control Knob. Fit the four casing screw covers.
(k) On completion of the commissioning and testing of the
system, the installer should hand over the appliance to the user
with reference to the following:
1. ive the Users Operating Instructions leaflet to the user.
2. Explain and demonstrate the lighting and shutdown
procedures.
3. Advise the user of the precautions necessary to prevent
damage to the system and to the building in the event of
the system remaining inoperative during frost conditions.
4. Stress the importance of an annual service by a competent
heating engineer.
To ensure continued efficient operation of the appliance, it is
recommended that it is checked and serviced as necessary at
regular intervals.
The frequency of servicing will depend upon the particular
installation conditions and usage but in general once a year
should be adequate.
It is the law that any service work must be carried out by a
competent person such as British as or other Corgi registered
personnel.
Before commencing any service operation turn off the gas
supply at the main gas service cock.
ACCESS FOR SERVICING
Remove the front casing by removing the four plastic screw
covers and then remove the four fixing screws.
Pull off the Temperature Control Knob.
Unscrew Temperature Control Knob housing.
Lift the casing clear.
10.1 Heat exchanger
Remove the collector hood assembly by slackening the two
retaining screws and pulling the hood out of the flue connector
duct. If the connector duct comes away with the collector hood
separate them and push the connector duct back into the stub in
the balanced flue assembly making sure that it is fully home and
resting against the two stops protruding from the sides of the
stub duct.
Inspect and clean the heat exchanger flueways if necessary.
To remove the heat exchanger, isolate the appliance from the
incoming cold supply and drain down the appliance via the
drain cock fitted.
Disconnect the heat exchanger flow and return pipes at the
water section and the base of the combustion chamber.
Remove the locknuts from the heat exchanger stubs and lift the
heat exchanger clear.
In hard water areas it may be necessary to descale the heat
exchanger body. Either a proprietary brand of descaler or a
solution of 10 parts of water to 1 part of hydrochloric acid
should be used. Fill the heat exchanger with this solution and
leave until the solution stops bubbling. Drain and thoroughly
wash out the exchanger with clean water.
Warning: Acid/water solutions must be used with extreme
caution. Take care not to splash on to the skin or into the eyes.
Wash any affected areas with large amounts of cold water and
seek medical advice.
10.2 Pilot assembly
Inspect the pilot injector and clean if necessary.
Check the pilot burner and electrode are clean and undamaged.
Clean or replace if necessary.
Pull off the pilot filter and clean.
10.3 Main burner
Disconnect the pilot gas pipe and thermocouple at the gas valve
and pull off the red cable from the Piezo unit.
Disconnect the pilot gas pipe from the pilot burner and remove
from the appliance complete with seal. Take care not to lose the
pilot injector.
Remove the two screws retaining the pilot bracket and lift the
complete assembly clear.
Undo the union connection below the burner. Lift the burner
clear and remove.
Inspect and clean the injectors if necessary.
Inspect and clean the main burner bars if necessary.
10. Slow ignition valve
Screw out the slow ignition valve (which is located on the right
hand side of the valve above the water flow pipe into the heat
exchanger. Item 17, Fig. 1.
10. Inspection and Servicing
Fig. 8. Gas pressure test point
8
Fig. 7. Gas control slide – shut down position
Piezo igniter
Gas control slide in this position

The ball within the valve should move freely. Check by shaking.
Check the O-ring and replace if necessary.
Re-assemble in reverse order.
10.5 Re-assembling the appliance
Re-assemble the appliance in reverse order ensuring the
following:
1. The collector hood outlet duct correctly enters the flue
connecting duct.
2. The washer in the main gas line union connection is
correctly located.
It is the law that any service work must be carried out by a
competent person such as British as or other Corgi registered
personnel.
Before commencing any service operation turn off the gas
supply at the main gas service cock.
11.1 Pilot burner/injector
Disconnect the pilot gas pipe and thermocouple at the gas valve
and pull off the red cable from the Piezo unit.
Disconnect the pilot gas pipe from the pilot burner and remove
from the appliance complete with seal. Take care not to lose the
pilot injector. Replace injector if necessary.
Remove the two screws retaining the pilot bracket and lift the
complete assembly clear complete with the red seal.
Pull off the pilot filter. Undo the screw fixing the spark electrode
/thermocouple retaining bar and lift these clear.
Replace the pilot burner/bracket and re-assemble in reverse
order.
11.2 Spark electrode/thermocouple
Follow the instructions in Section 11.1 and replace the faulty
component.
11.3 Main burner
Disconnect the pilot gas pipe and thermocouple at the gas valve
and pull off the red cable from the Piezo unit.
Disconnect the pilot gas pipe from the pilot burner and remove
from the appliance complete with seal. Take care not to lose the
pilot injector.
Remove the two screws retaining the pilot bracket and lift the
complete assembly clear.
Undo the union connection below the burner. Lift the burner
clear of the union and push the front of the burner up into the
combustion chamber so that it is standing vertically against the
rear. Pull the rear of the burner forward so that the burner is now
upside down and work out between the combustion chamber
skirt and gas pipe.
Replace the burner and re-assemble in reverse order taking care
that the seals around the igniter cable/thermocouple and pilot
gas pipe are correctly seated in the combustion chamber base
and the pilot injector has been fitted.
11. Heat exchanger
Remove the collector hood assembly by slackening the two
retaining screws and pulling the hood out of the flue connector
11. Replacement of Parts duct. If the flue connector duct comes away with the collector
hood, separate them and push the connector duct back into the
stub in the balanced flue assembly making sure that it is fully
home and resting against the two stops protruding from the
sides of the stub duct.
Isolate the appliance from the incoming cold water supply and
drain down the appliance via the fitted drain cock.
Disconnect the heat exchanger inlet and outlet pipes at the
water section and at the base of the combustion chamber.
Remove the locknuts from the heat exchanger stubs and lift the
heat exchanger clear.
Replace the heat exchanger and re-assemble in reverse order.
11.5 Piezo unit
Pull off the two wires from the rear of the unit, unscrew the
plastic retaining nut on the control panel and push out the Piezo
unit.
Replace and re-assemble in reverse order.
11.6 Water section
Isolate the appliance from the incoming cold water supply and
drain down the appliance via the fitted drain cock.
Disconnect the four union connections.
Release the two screws between the water section and gas
section and pull the water section clear.
The diaphragm within the valve can be replaced by removing the
three fixing screws holding the valve body together.
The water filter fitted into the incoming cold water tapping can
be cleaned or replaced by pulling it out.
Re-assemble in reverse order.
11.7 Gas valve
Remove the water section as described in Section 11.6.
Disconnect the pilot gas pipe and thermocouple from the gas
valve.
Pull off the two cables from the rear of the Piezo unit.
Release the main gas pipe union connection below the
combustion chamber and lift the valve clear complete with the
control panel.
Remove the Piezo unit as described in Section 11.5.
Remove the control facia by taking out the four fixing screws and
lifting clear complete with slider knob.
Prise out the slider bar and remove the two screws retaining the
control frame and lift clear.
Replace the gas valve and re-assemble in reverse order.
9
3. The seals around the igniter cable/thermocouple and pilot
gas pipe are correctly seated in the combustion chamber
base and the pilot injector has been fitted.
Turn on the gas supply at the main gas service cock and check
for gas soundness in accordance with the current edition of BS
6891 while the appliance is running.
Re-commission the appliance as detailed in Section 9.

12. Fault Finding
13. Short Parts List
Problem Cause Solution
Incorrect water temperature Incorrect gas rate Check the gas supply to appliance gas service cock
Open the gas service cock
Check the burner pressure
Check the inlet pressure
Water section sticking or faulty Clean or replace
Incorrect water flow rate Incoming supply valve closed Open supply valve
Low water pressure Check the water pressure is above 0.1 bar
Water section sticking or faulty Clean or replace
Noise Scale in heat exchanger Descale and service
High gas rate Check the burner pressure
Low water flow rate Check the water flow rate
Pilot flame will not stay alight No gas supply Connect gas supply
as service cock closed Open gas service cock
Air in gas line Purge the line
Pilot injector blocked Clean/replace the injector
No spark Clean or replace the electrode, Piezo unit or cable
Main burner will not light as pressure low Check the inlet and burner pressure
as service cock partially closed Open the gas service cock
Low water rate Check the water rate
Water section diaphragm faulty Replace the diaphragm
as valve faulty Replace the gas valve
Explosive ignition Reduced pilot flame Clean or replace the pilot injector assembly
Faulty slow ignition valve Replace the slow ignition valve
Part Manufacturer's Reference
Pilot Burner 8 718 105 048
Pilot Injector 8 708 200 005
Thermocouple 8 747 202 082
Spark Electrode 8 708 107 002
Piezo Unit 8 748 108 023
Water Section 8 707 002 457
Diaphragm 8 700 503 051
Slow Ignition Valve 8 708 503 063
as Valve 8 707 011 028
Temperature Control Knob 8 702 000 111
Control Facia Plate 8 701 000 104
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11
Additional Information
1. CE Certification
006
2. Symbols on Data Plate
Pn-Nominal useful output
Pmin - Minimum useful output
Qn- Nominal heat input
Qmin -Minimum heat input
Pw- Maximum service water pressure
Pwmin -Minimum service water pressure
Type: C11 - Natural draught appliances
MODEL WR325-1AD... WR325-1AV...
CE NUMBER CE 0085 AQ 0293
CATE ORIES I2H I3+
TYPE C11

This booklet is accurate at the date of printing but will be superseded and should be disregarded if specifications and/or appearances are changed in the interests
of continued improvement.
All goods sold are subject to our official Conditions of Sale, a copy of which may be obtained on application.
PUBLICATION 6 720 603 9 , ISSUE 1 – JULY 1997
Bosch Thermotechnik
Worcester Heat Systems Limited, Cotswold Way, Warndon, Worcester WR4 9SW.
Telephone: [phone]. Fax: [phone].
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