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.

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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.

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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

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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

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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

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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

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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

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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.

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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

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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