Potterton Medway Super Quick guide

INSTALLATION AND SERVICE INSTRUCTIONS
Medway Super
Gas Fired Water Heater
G.C. NO. 52 476 39
G.C. NO. 52 476 41 (When Fitted with Low Pressure Throttle Kit)
NON SPOUTED MULTIPOINT MODEL FOR USE WITH NATURAL GAS
THE GAS SAFETY (INSTALLATION AND USE) REGULATIONS 1984.
“In your own interest, and that of safety, it is law that all gas appliances are installed by competent persons, in accordance
with the above regulations. Failure to install appliances correctly could lead to prosecution.”
Installation must be in accordance with the Building Regulations, Byelaws of the Water Undertaking, and I.E.E. Wiring
Regulations. It should be in accordance also with any relevant requirements of the Local Gas Region and Local Authority
and the relevant recommendations of the following British Standard Codes of practice: BS 6891, BS 5440:1:2 and BS 5546.
LEAVE THESE INSTRUCTIONS WITH THE USER FOR USE ON FUTURE CALLS
IMPORTANT
PLEASE READ THIS BOOK
BEFORE INSTALLING,
OPERATING OR
SERVICING THIS
APPLIANCE.

2
IMPORTANT
If this appliance is to be installed on a low water pressure installation, obtain the
Main Medway Super Low Pressure Throttle Kit - Part No 31/17756
(G.C. No. 285 888) before proceeding with the installation.
1. INTRODUCTION – page 2
The Main Medway Super is a room sealed instantaneous water heater designed to supply hot waterto several outlets which
may be situated in different rooms, but not necessarily at the same time.
The pilot is lit by a piezo spark ignitec no batteries or electricity are required. The main burners will automatically light when a
domestic hot water tap is turned on and go out when the tap is turned off.
This appliance is not suitable for use with a swivel spout.
ENERGY CUT-OFF DEVICE
This appliance contains an Energy Cut-Off Device that will shut down the gas supply to the appliance if the water within
the heat exchanger exceeds the anticipated temperature limit after the hot water tap has been turned off - See Page 21.
VENTILATION
Being a room sealed appliance, the Medway Super does not require an air vent in the room or space in which it is installed.
Where this appliance is installed in a compartment, air vents to the compartment at both high and low levels, should be
provided for cooling.
Further guidance is given in BS 5440 Pt.2.
Position of Air Vent
High Low
In compartment which is ventilated to room 274 cm² 274 cm2
42 in² 42 in2
In compartment which is ventilated to outside 137 cm² 137 cm2
21 in2 21 in2
GENERAL
IMPORTANT: The area of wall covered by the appliance must be flat.
The clearances required around the Flue Terminal are shown on the Flue Template supplied with the Terminal Pack.
The appliance must be fitted on an external wall to allow the Flue Terminal to pass directly through the wall to the outside
air.
If the appliance is to be installed into a “SEDUCT” the minimum duct required is 228mm (9in.) deep, 349mm (1 5½in.) wide.
This appliance may take the place of an existing appltance and will mount onto the original flue terminal of any of the
following: AVON, BRISTOL, MEDINA, MEDINA D/L, MEDWAY, MERSEY, SEVERN 3, SEVERN 4, SEVERN 5 and TRENT.

3
2. TECHNICAL SPECIFICATIONS – page 3
Finish White stoved paint with contrasting chassis
Weight Packed 21.8 kg. (48.0 lb.)
Weight without Water 18.6 kg. (41.0 lb.)
Weight with Water 19.4 kg. (42.7 lb.)
Water Capacity 0.75 litre(0.17 all.)
Input 30.3 kW (103,000 Btu/h.)
Maximum Output 23.3 kW (79,500 Btu/h.)
Row Rates 6.5 Vmin at 5000 rise
Minimum pressure head requirement at water heater * 1 bar (14.6 psi) under flow conditions
Maximum pressure head 13 bar (189 psi)
Gas group G20
Burner injector (14 off) 1.2mm marking 120
Pilot injector 0.27mm markinq A
Nominal burner pressure -** (maximum input) 12.5mbar (5 in. w.g.)
Connections - Gas 15mm
- Water 15mm Compression
Balanced flues (telescopic) Wall thickness available 100mm - 150mm (4in - 6in) - Part No 31/1 0321
150mm - 230mm (6in - 9in) - Part No 31/10322
230mm - 380mm (9in - iSin) - Part No 31/1 0323
380mm - 610mm (iSin - 24in) - Part No 31/1 0324
Flue Terminal Guard (Optional) Part No 10/10262
Notes: * Additional external pipework and fittings may affect the resistance and must be taken into account on installation
** The nominal burner pressure should be 12.5 mbar and will only be obtained if the appliance inlet pressure is correct at
20 mbar even when the appliance is running at full heat input. The meter should be capable of passing 100ft3/h of
natural gas plus the requirements of any other gas appliances.
MINIMUM CLEARANCES
Above: 60mm
Below: 75mm
Sides: 5mm (Each)
Front: 220mm (To allow for removal of outer case)
For ease of servicing, allow as much clearance as possible below the appliance.
If the appliance is to be installed in a cupboard, the ventilation openings in the cupboard must NOT be blocked. DO NOT
USE THE CUPBOARD FOR STORAGE.
Fig 1

4
3. INSTALLATION – page 4
A. LOCATION
1. If the appliance is to be fixed to a suitable existing
terminal first isolate and remove the old appliance.
Leave the flue terminal in place. Retain the fixing nuts
and washers.
Make good any damage to the brickwork or plaster
amund the terminal. Cut off the existing pipework at a
convenient point below the appliance.
2. If installing a new flue terminal, guidance is given on the
template sheet supplied with the terminal pack.
NOTE: Where the appliance is to be installed into a
SEDUCT the minimum duct required is 228mm (9in) deep,
349mm (15½in) wide.
Fig 2
3. Where the building regulations require it, a flue terminal
guard should be fitted symmetrically around the outer
part of the flue terminal.
4. Unpack the water heater. Find the bags of accessories
before discarding the packaging.
5. Turn the temperature selector to ‘+‘ then slide off the
bottom cover. Remove the three screws securing the
outer case and carefully lift it off.
Fig 3
6. Use the self adhesive discs supplied to cover the
unwanted fixing holes in the back of the new appliance
as shown.
Fig 4

5
3. INSTALLATION – page 5
7. Fit the flue terminal sealing strip (packed separately in
the carton) into the recess around the flue aperture in
the back of the appliance.
8. Lift the appliance into position, locating the flue outlet
into the circular duct on the flue terminal.
9. Secure with die approprate nuts and washers.
Fig 5
B. GAS CONNECTION
IMPORTANT: Blow out all foreign matterfrom the supply
pipe before connecting to the gas service cock.
15mm copper pipe to BS 2871 may be used for a simple
supply not exceeding 3 metres (l0ft) from the gas meter.
Where the installation contains many bends orthe length is in
excess of 3 metres (l0ft), then the use of 22mm copper pipe
is necessary.
1. Assemble the filter, ‘O’ ring and inlet tail to the gas inlet.
2. Depending on whetherthe main supply pipe is to be
routed vertically or horizontally to the appliance, connect
the gas service cock (stamped ‘G’) either directly to the
gas inlet tail or within the supply pipe. NOTE: The
service cock should be as close to the appliance as
possible and the ON/OFF screw in an accessible
position.
3. Ensure that the gas supply is turned OFF at the mains.
4. Connect to the gas supply.Service cock
5. Turn ON the gas supply and the gas service cock then
test for gas soundness (BS 6891).
IMPORTANT: DO NOT TRY TO LIGHT THE
APPLIANCE AT THIS STAGE. TO ALLOW THE MAIN
BURNER TO IGNITE WITHOUT
THE OUTER CASE SECURED IN POSITION
IS A HAZARD.Fig 6

6
3. INSTALLATION – page 6
C. WATER CONNECTIONS
IMPORTANT: Flush out all foreign matter from the supply
pipe before connecting to the service cock.
1. Assemble the filter, olive and inlet tail to the inlet
adaptor. NOTE: The inlet tail need not be used as a
vertical supply can be routed directly onto the inlet
adaptor.
2. Depending on whether the main supply pipe is to be
routed vertically or horizontally to the appliance, connect
the water service cock either directly to the water inlet
tail or within the supply pipe. NOTE: The service cock
should be as dose to the appliance as possible and the
ON/OFF screw in an accessible position.
3. Ensure that the mains water supply is turned
OFF.
IMPORTANT: When routing the supply pipe to the
appliance, ensure that it can be lowered by approx 25mm to
allow for disconnection when servicing.
4. Connect the hot water supply pipes to the water outlet -
15mm compression.
5. Turn ON the mains water supply, turn ON the water
service cock and open all the hot water outlets to allow
water to flow. Purge the air from the system by closing
the hot water outlets starting with the lowest level and
ending with the outlet at the highest level.
6. Check for water leaks and remedy if found.
IMPORTANT: DO NOT TRY TO LIGHT THE
APPLIANCE AT THIS STAGE.
Fig 7
D. LINT FILTER
This appliance has a lint filter fitted around the
base of the pilot tube.
Ensure that the filter gauze is located inside both end caps
and that the complete assembly is correctly seated over the
union nut at the base of the pilot tube.
Fig 8

7
4. COMMISSIONING – Page 7
WARNING: The outer case of this appliance is not merely a
cosmetic device. It is a functioning component in the air
supply to the burner and MUST BE replaced with great care
NOW, before any attempt is made to light the burners.
TO ALLOW THE MAIN BURNER TO IGNITE WITHOUT
THE CASE IN POSITION IS A HAZARD.
1. Refit the outer case ensuring it is correctly seated then
secure (3 screws). Ensure that the temperature selector
control rod is set as shown (setting ‘+‘).
Fig 9
2. Ensure that the gas and water supplies are turned ON.
3. Ensure that all hot water outlets are closed.
4. Remove the screw and sealing ring from the burner
pressure test point and attach a pressure gauge.
Fig 10
5. Fully depress and hold the ON button ’ and
repeatedly press and release the IGN button’ ‘until
the pilot is lit. The pilot flame can be observed through
the pilot viewing window.
6. Hold the ON button ’ in for a further 10 seconds after
the pilot is lit, then release. If die pilot goes out, repeal
the lighting operation keeping the ON butt on
‘‘depressed a little longer.
7. Test for gas soundness using a suitable leak detection
fluid on all external gas joints.
8. Open a hot water outlet and the burner will ignite. Allow
the water to run for a few minutes then check the burner
pressure - it should be i2.5 mbar (5 in w.g.), if the
pressure is not correct see the FAULT FINDING section. Fig 11

8
4. COMMISSIONING – Page 8
NOTE: If a gas rate check is required, the gas
consumption after 3 minutes running
should be approximately 48.5 l/mm
(1.7 ft3/min).
9. Turn the temperature selector spindle from right to left
(‘+’ to ‘-‘), there will be a noticable change in the outlet
temperature. Turn the rod back to the right (‘+‘).
10 Turn OFF the hot water outlet and press the OFF
button’ ‘on the appliance. Remove the pressure
gauge and replace the screw and sealing ring.
11 Relight the pilot. Turn ON a hot water outlet and check
for gas soundness at the pressure test point.
12 Turn OFF the hot water outlet. Slide the bottom cover
onto the appliance. Ensure that the temperature selector
spindle is aligned with the selector knob, push the
bottom cover and with slight adjustment the selector will
positively locate on the spindle.
Fig 12
Explain to the user how to operate the appliance.
- see the “Instructions for Use” booklet.
Show the user the position of the Identification Badge.
HAND OVER THE “INSTRUCTIONS FOR USE” TO ThE
USER.
LEAVE THESE “INSTALLATION AND SERVICE”
INSTRUCTIONS WITH THE USER
FOR USE ON FUTURE CALLS.
ADVISE THE USER THAT FOR CONTINUED
EFFICIENT AND SAFE OPERATION OF THE
APPLIANCE, IT IS IMPORTANT THAT
SERVICING IS CARRIED OUT AT
INTERVALS RECOMMENDED BY THE
LOCAL BRITISH GAS REGION OR C.O.R.G.I.
REGISTERED INSTALLER.
Fig 13
5. SERVICING – page 8
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 per year should be adequate.
IMPORTANT: It is the law that any service work must be carried out by competent persons such as British Gas or other
c.o.r.g.i. registered personnel.
NOTE: In hard water areas, scale may build up on the push rod , seals and on the underside of the diaphragm housing.
They may require regular descaling and regreasing.

9
5. SERVICING – page 9
Operate the appliance noting any faults in the component
units. Carry out the servicing procedure then correct any
other faults by reference to ‘Replacement of Parts’, in which
section you will find details of how to dismantle and
reassemble the following detailed components. Check that
the burner ignition is smooth and quiet when a hot tap is
opened. The burner ignition has been factory set and should
not need adjustment. However, if adjustment is required a
slow ignition screw is fitted to the appliance and is situated
above the cap screw in the water governor body (fig. 16).
The screw is factory set 2 full turns out (anti-clockwise) from
the fully in position. Turning the screw clockwise delays the
ignition, anti-clockwise advances the ignition.
Fig 14
WARNING: NEVER OPERATE THIS
APPLIANCE WITH THE OUTER CASE
REMOVED.
1. Check the piezo unit, flame safety device and
thermocouple, clean or replace if necessary.
2. Remove the burner assembly and clean using a soft
brush or vacuum cleaner.
3. Check the pilot injector and clean or replace if
necessary. Also clean the lint filter.
4. Remove the water governor assembly complete with
push rod. Replace the seals if necessary. Descale and
regrease the push rod, washers and diaphragm housing
using Dow Corning 111 silicone grease.
5. Check for water and gas soundness. Replace ‘O’ rings,
sealing washers and gaskets where required. Fig 15
6. Clean any deposits off the heating unit by washing or
brushing. Descale the heating unit if required.
Fig 16

10
6. REPLACEMENT OF PARTS – Page 10
IMPORTANT: THE FOLLOWING WORK SHOULD ONLY BE CARRIED OUT BY A COMPETENT SERVICE
ENGINEER. E.G. BRITISH GAS OR CORGI REGISTERED PERSONNEL
1. IF WATER IS DRAINED FROM THE SYSTEM DURING SERVICING, TURN ON ALL HOT TAPS TO PURGE AIR
FROM THE WATER SYSTEM. TURN THEM OFF IN SEQUENCE, STARTING WITH THE TAP AT THE LOWEST
LEVEL
2. WHEN REPLACING ANY PARTS, RE-ASSEMBLE IN REVERSE ORDER UNLESS OTHERWISE STATED.
This chart shows the steps to be taken in order access a specific part or perform a particular function. Use this chart in
conjunction with the detailed procedures on the following pages.
START
General Access/Main Burner
Remove Piezo Unit
Remove Pilot Injector
Remove Thermocouple and
Electrode
Remove Pilot Injector
Remove Water Governor and
Push Rod
Remove Energy Cut-Off Device
Drain the Appliance
Descale and Regrease
Remove Heating Unit
Remove Flame Failure Device
Remove Water Govenor
Venturi
Descale Heating Unit
Remove the Automatic Valve &
Burner Manifold Complete

11
6. REPLACEMENT OF PARTS – Page 11
6.1. PIEZO UNIT
It will NOT be necessary to remove the outer
case.
a. Slide out the bottom cover.
b. Disengage the electrode lead from the piezo unit.
c. Remove or loosen and pull aside the spark button
retainer, taking care not to lose the shakeproof washer.
d. Pull off the button and unscrew (anti-clockwise) the
piezo from its housing.
NOTE: When refitting the bottom cover, ensure the
temperature selector spindle is aligned with the selector.
Push the bottom cover and with slight adjustment, the
selector will positively locate on the spindle.
Fig 17
6.2. GENERAL ACCESS/MAIN BURNER
a. Turn OFF the gas and water supplies at the service
cocks.
b. Slide out the bottom cover.
c. Remove the 3 fixing screws and pull off the outer case.
Fig 18
d. Remove 4 fixing screws from the burner assembly (2
each side).
e. Remove 2 screws securing the front to the heating unit.
f. Pull the burner assembly slightly forwards to clear the
injectors, then pull apart and withdraw taking care not to
snag the pilot assembly.
NOTE: If required, the burner assembly can be dismantled
and the burner bars replaced individualy. On re-assembly
ensure that the burner inlets locate in the 14 holes.
NOTE: On re-assembly of the burner assembly take care
not to snag the pilot assembly. Ensure the front face of the
assembly has located on the two studs on the heating unit.
Re-fit the bottom cover as outlined in Section 6.1
Fig 19

12
6. REPLACEMENT OF PARTS – Page 12
6.3. THERMOCOUPLE AND SPARK ELECTRODE
a. Gain general access - see 6.2.
b. Remove the fixing screw and bracket then lower the
spark electrode.
c. Disconnect the nut securing the thermocouple to the
interrupter at the chassis base.
d. Disconnect the electrode lead from the back of the piezo
unit, pull the lead up through the grommet and remove.
e. On re-assembly, ensure that the pilot tube bends
towards the rear of the appliance.(The thermocouple will
be vertical and nearest the burner manifold).
Fig 20
6.4. PILOT INJECTOR
a. Gain general access - see 6.2.
b. Lift up the lint filter, disconnect the union nut and
carefully lift up the pilot tube taking care not to lose the
pilot injector.
c. On re-assembly ensure the pilot injector is correctly
seated (taper side down) and that the lint filter is
correctly assembled and located on the union nut.
NOTE: The lint filter can be cleaned if required.
Fig 21
6.5. FLAME SAFETY DEVICE
a. Gain general access - see 6.2.
b. Disengage the electrode lead from the piezo unit.
c. Release the thermocouple from the back of the flame
safety device.
d. Release the union nuts above and below the flame
safety device.
e. Release the union nut securing the pilot transfer tube to
the flame safety device.
f. Remove the 3 screws securing the flame safety device
to the chassis base and carefully withdraw the unit.
g. Re-assemble in reverse order.
Fig 22

13
6. REPLACEMENT OF PARTS – Page 13
h. Test for gas soundness as follows:-
-Ensure the water service cock is in the OFF
position. This will ensure water cannot flow and
open the automatic valve.
-Turn ON the gas, purge and light the pilot, this will
pressurise the burner supply pipe.
-Test the gas supply to flame safety device and
burner supply pipe above the flame safety device for
gas soundness using leak detection fluid.
i. Re-assemble remaining parts and ensure the water
service cock is in the ON position.
Fig 23
6.6. TO DRAIN THE APPLIANCE
a. Ensure that the gas and water service cocks are turned
OFF.
b. Open a hot water outlet.
c. Have a suitable container to hand . Remove the drain
screw from the water service cock and allow the water to
drain.
Fig 24
6.7. WATER GOVERNOR
a. Gain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Release the inlet water connection and lower the
pipework to clear the inlet.
d. Release the union nut and clamping plate then remove
the feed pipe. Replace the ‘O’ ring.
Fig 25

14
6. REPLACEMENT OF PARTS – Page 14
e. Remove 2 screws above the chassis base securing the
governor to the automatic valve.
f. Remove 3 screws above the chassis base securing the
governor to the chassis base.
g. Carefully withdraw the governor complete with pressure
relief valve, TAKE CARE NOT TO BEND THE PUSH
ROD. IF THE ROD IS BENT, A NEW ONE MUST BE
FITTED.
NOTE: When removing the water governor, the
temperature selector spindle will disconnect itself from the
governor. On re-assembly the rod must be positioned before
the unit is secured in place.
h. Remove the push rod.
i. Remove 8 screws and separate the two halves of the
water governor.
Fig 26
DESCALE AND REGREASE
jRemove both the brass washer and ‘O’ ring from the top
opening. Clean the washer.
kClean the top opening then pack with a silicone grease
such as Dow Corning 111. Fit a new ‘O’ ring and re-fit
the brass washer.
I. Hold the thrust plate, remove the fixing nut and lift out
the diaphragm assembly. Clean or renew as required.
On re-assembly, tighten the fixing nut finger tight plus a
¼ turn only.
mCheck and if necessary replace the transfer port ‘O’ ring.
nEnsure the diaphragm assembly is correctly seated then
re-assemble the two halves of the governor. Insert the 8
screws and secure finger tight. Fully tighten all 8 screws
in the order shown.
oClean, regrease and re-fit the push rod or replace with a
new one.
Fig 27
Fig 28

15
6. REPLACEMENT OF PARTS – Page 15
6.8. WATER GOVERNOR VENTURI
a. Gain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Release the union nut and clamping plate then remove
the feed pipe.
d. Using a large flat bladed screwdriverthat will engage
both slots, remove the venturi.
e. Clean and re-fit.
Fig 29
6.9. AUTOMATIC VALVE AND BURNER
MANIFOLD COMPLETE
a. Gain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Remove the water governor - see 6.7.
d. Release the union above the flame safety device. Do not
lose the ‘O’ ring.
e. Release the retaining plate (2 screws) and remove the
burner supply pipe. Do not lose the ‘O’ ring.
f. Prise the manifold location brackets apart and carefully
lift out the complete assembly.
IMPORTANT: The automatic valve and burner
manifold are only available as a combined assembly.
Retain all screws and ‘O’ rings from the old assembly or
renew.
NOTE: On re-assembly slide the pressure test point
extension tube through the grommet before locating the
manifold against the location brackets. Fig 30
g. Re-fit the water governor.Drain screw
h. Re-connect the burner supply pipe.
i. Test for gas soundness as follows:-
-Ensure the water service cock is in the OFF
position, this will ensure that water CANNOT flow
and open the automatic valve. Water
-Turn ON the gas, purge and light the pilot, service
this will pressurise the burner supply pipe. cock
-Test the burner supply pipe joints for gas soundness
using leak detection fluid.
jRe-assemble remaining parts and ensure the water
service cock is in the ON position.
IMPORTANT: If the automatic valve and burner manifold
complete is dismantled, it can only be
tested for gas soundness under pressure
AFTER blanking off all the injectors. Fig 31

16
6. REPLACEMENT OF PARTS – Page 16
6.10. HEATING UNIT
a. Gain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Remove the 2 screws securing the energy cut-off device
to the heating unit (located top front left).
d. Disconnect the 2 unions.
e. Remove 4 screws securing the unit to the chassis.
f. Carefully pull the unit from the top and lift. DO NOT lose
the ‘O’ rings and washers.
g. Remove the primary flue, secured by 4 screws (2 front,
2 rear).
Fig 32
6.11. DESCALING THE HEATING UNIT
WARNING: ACID/WATER SOLUTION MUST BE USED
WITH EXTREME CAUTION. TAKE CARE NOT TO SPLASH
ONTO SKIN OR INTO THE EYES. WASH ANY AFFECTED
AREAS WITH LARGE AMOUNTS OF COLD WATER AND
SEEK MEDICAL ADVICE.
CARRY OUT THE FOLLOWING OPERATION OUT OF
DOORS. ACID/WATER SOLUTION CAN DAMAGE
FURNISHINGS ETC.
aGain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Remove the heating unit - see 6.10.
d. Invert the heating unit on a suitable bench or table.
e. Using rubber tube and acid resisting tanks, assemble as
shown in fig.33.
f. All the upper container with a proprietary brand of
descalent or a solution of 10 parts water to 1 part
hydrochloric acid. The water should preferably be hot,
then add ACID to WATER, not water to acid.
g. Adjust the pinch cock and allow the fluid to slowly pass
through the heating unit into the collecting tank.
h. Continue the process until the fluid ceases to bubble. It
may be necessary to replenish the solution.
i. Disconnect and thoroughly wash out the heating unit
with clean water.
Fig 33

17
6. REPLACEMENT OF PARTS – Page 17
6.12. PILOT VIEWING GLASS AND SEAL
a. Complete steps a., b. and c. of section 6.2.
b. The viewing glass and seal are fixed to the inside of the
outer case by 2 metal tabs. Bend back the tabs and
remove the glass and seal. Secure the new glass and
seal to the outer case by bending over the 2 spare
straight tabs.
Fig 34
6.13. ENERGY CUT-OFF DEVICE
a. Gain general access - see 6.2.
b. Disconnect the energy cut-off leads from the interrupter
located on the underside of the chassis.
c. Remove the 2 screws securing the energy cut-off device
to the heating unit (located top front left).
d. Pull the leads complete with grommets up through the
chassis base.
e. Fit the new energy cut-off device which comes complete
with grommets.
Fig 35

18
7. FAULT FINDING – Page 18
SYMPTON POSSIBLE CAUSE SOLUTION
PILOT WILL NOT LIGHT 1. Gas not turned on. 1. Turn on the gas at the gas
service cock and/or the main
gas line.
2. Air in gas line. 2. Purge the air line by depressing
and holding the centre ON
button, this may take 2-3
minutes.
3. Incorrect pilot lighting procedure. 3. Follow the lighting instructions
located on the bottom cover or
refer to the “Instructions for
Use”.
4. Electrode lead not connected to the
rear of the spark igniter. 4. Re-connect the electrode lead.
5. Incorrect spark gap. 5. The gap between the electrode
tip and the pilot hood should be
3-4mm.
6. Current tracking to earth. 6. Check the electrode lead is
routed clear of all metal parts.
7. Pilot injector blocked. 7. Clear injector by blowing through
or replace with pilot injector Part
No 19/12690. Also clean the lint
filter located at the base of pilot
tube.
8. Faulty components. 8. Replace any faulty components
found. Piezo Unit - Part No 10/
11935. Electrode Assembly –
Part No 10/1 7493.
9. No gas to the appliance. 9. Call in your local British Gas
Region.
PILOT LIGHTS BUT WILL NOT
REMAIN ALIGHT 1. Thermocouple connections loose. 1. Tighten the connections.
2. Pilot flame ‘soft’ or too small to heat
the thermocouple tip. 2. Pilot injector partially blocked, clear by blowing through or replace.
Check the gas inlet pressure is
correct - 20 mbar. Also clean the lint
filter located at the base of the pilot
tube.
3. Thermocouple worn out or damaged. 3. Replace the thermocouple – Part No
10/17461.
4. Faulty magnet unit in the flame safety
device. 4. Replace flame safety device- Part No 10/1 3477.
5. Energy cut-off device connections
loose. 5. Tighten connections.
6. Energy cut-off device may be faulty. 6. Check for continuity and replace if
necessary - Part No 10/17792.

19
7. FAULT FINDING – Page 19
SYMPTON POSSIBLE CAUSE SOLUTION
PILOT LIT BUT MAIN BURNER
WILL NOT LIGHT ON WATER
FLOW
1. Gas inlet pressure low. 1. Call in your local British Gas
Region
2. Low waterflow caused by blocked
water filter. 2. Clean the debris from the filter.
3. Faulty diaphragm. Will also cause a
high water rate 3. Replace the diaphragm Assembly - Part No 10117534.
4. Automatic gas valve push rod jammed.
May also cause a high water rate. 4. Dismantle clean and regrease using Dow Corning 111 silicone
grease. Handle the push rod
with care, do not bend.
5. Slow ignition screw incorrectly set. Will
also cause a high water rate. 5. See Fig. 16 for the position of the screw. Turning the screw
clockwise delays the ignition,
anti-clockwise advances the
ignition. The screw should be
set 2 full turns out (anti
clockwise) from the fully in
position. When correct the
burner ignition should be
smooth and quiet when a hot
water outlet is opened.
NO OR LOW WATER FLOW
RATE 1. Blocked water filter. 1. Clean the debris from the filter.
2. Heat exchanger blocked with lime. 2. Descale or replace - Part No
10/17758.
3. Loss of service water main pressure. 3. Contact your Local Water
Authority.
4. Low water pressure. 4. Check that the low pressure
inlet has been used and that the
low pressure throttle kit (P/N
31/17756) has been fitted.
HIGH WATER FLOW RATE
See LOW WATER TEMPERATURE
HIGH WATER TEMPERATURE 1. Automatic gas valve push rod sticking.
Water rate will be normal. 1. Dismantle clean and regrease using Dow Coming 111 silicone
grease. Handle the push rod
with care, do not bend.

20
7. FAULT FINDING – Page 20
SYMPTOM POSSIBLE CAUSE SOLUTION
LOW WATER TEMPERATURE 1. Temperature selector set to ‘-‘. 1. Turn selector to ‘+’.
2. Gas pressure too low. 2. Check and clean gas filter, also
check gas inlet pressure.
3. Faulty diaphragm. Will also cause a
high water rate. 3. Replace the diaphragm assembly - Part No 10/17534.
4. Automatic gas valve push rod sticking.
May also cause a high water rate. 4. Dismantle dean and regrease using Dow Corning 111 silicone
grease. Handle the push rod with
care, do not bend.
5. Slow ignition screw incorrectly set. Will
also cause a high water rate. 5. See Fig. 16 for the position of the screw. Turning the screw
clockwise delays the ignition,
anti-clockwise advances the
ignition. The screw should be set
2 full turns out (anti clockwise)
from the fully in position. When
correct the burner ignition should
be smooth and quiet when a hot
water outlet is opened.
NOISY HEATER 1. Heat exchanger scaled. Ultimately this
will cause the heat exchanger fins to
discolour and buckle.
1. Descale or replace - Part No
10/1 7558.
2. Noisy ignition could be caused by
incorrect setting of the slow ignition
screw.
2. See Fig. 16 for the position of
the screw. Turning the screw
clockwise delays the ignition,
anti-clockwise advances the
ignition. The screw should be set
2 full turns out (anti-clockwise)
from the fully in position. When
correct the burner ignition should
be smooth and quiet when a hot
water outlet is opened.
3. Reduced pilot rate caused by dirt. 3. Clear injector by blowing through
or replace with pilot injector Part
No 19/12690. Also clean the lint
filter located at the base of pilot
tube.
4. Burner aeration ports and main flame
ports blocked. 4. Carefully clean the burners with a vacuum cleaner.