Johnson & Starley SCT 75-75 G Guide

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SCT 75-75 G
SCT100-95G
WATERSTORAGEHEATERS
UNITED KINGDOM / IRELAND
MODEL
INSTALLATION- AND USER
INSTRUCTIONS

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Read these installation instructions first before installing the appliance. Carefully read
the user instructions before igniting the appliance. Failure to follow these instructions
may lead to risk of explosion and/or fire and could cause material damage and/or bodily
harm.
Installation and commissioning should be carried out by a qualified competent installer.
The type of gas and the value at which the appliance is set standard in the factory are
registered on the rating plate. The appliance may only be installed in a room if this room
meets the ventilation requirements.
STATEWATERHEATERSACCEPTSNORESPONSIBILITYFORWARRANTY,
SERVICEAND/ORPRODUCTLIABILITYINCASEOFUNAUTHORIZED
ALTERATIONS,PRODUCTMODIFICATIONSORREPAIR.

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CONTENTS PAGE
1. General........................................................................................................ 5
1.1 Description of the appliance .......................................................................... 5
1.2 Technical safety equipment ........................................................................... 6
1.3 Technical description..................................................................................... 8
1.3.1 Dimensions .................................................................................................... 8
1.3.2 Technical data ............................................................................................. 10
2. Fortheinstaller. ...................................................................................... 11
2.1 Installation instructions ................................................................................ 11
2.1.1 Installation .................................................................................................... 11
2.1.2 Water connections ...................................................................................... 11
2.1.3 Gas connection ........................................................................................... 12
2.1.4 Flue system ................................................................................................. 13
2.1.5 Draught diverter........................................................................................... 13
2.2 Commissioning ............................................................................................. 14
2.3 Pilotadjustment ............................................................................................ 15
2.4 Putting out of operation................................................................................ 15
2.5 Temperature regulation................................................................................ 15
2.6 Setting the nominal heat input ...................................................................... 16
2.7 Conversion procedure................................................................................. 16
2.8 Maintenance ................................................................................................ 18
2.8.1 Sacrificial anode .......................................................................................... 18
2.8.2 Cleaning ....................................................................................................... 19
2.8.3 Decalcification ............................................................................................. 19
2.8.4 Spare parts.................................................................................................. 19
2.9 Inletcombination .......................................................................................... 20
2.10 Fault finding ................................................................................................. 20
2.11 Gassmell..................................................................................................... 20
2.12 Condensation............................................................................................... 20
3. For the user. ............................................................................................. 21
3.1 Commissioning ............................................................................................. 21
3.2 Use .............................................................................................................. 21
3.3 Putting out of operation................................................................................ 21
3.4 Fault finding ................................................................................................. 22
4. Warranty. .................................................................................................. 23

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Drawing 1 - Cross-section of the
appliance
1) Draught diverter
2) Hot water outlet
3) Insulationmaterial
4) Flue tube
5) Glass lined tank
6) Gas control valve
7) Cold water inlet pipe
8) T&P safety connection
9) Steel jacket
10) Flue baffle
11) Sacrificial anode
12) Drain tap
13) Atmospheric burner

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1. GENERAL
1.1 Description of the
appliance
Construction of the water heater is in
accordance with the European
standard for gas heated water storage
heaters for sanitary application (EN 89).
The appliance thus meets the European
Directory for Gas Appliances and is
therefore entitled to carry the CE-
marking. It is an open flued appliance
without ventilator and with a flue gas
down draught safeguard (category
B11BS). The water heater is suitable
for a maximum working pressure of 8
bar. The water-heater tank is
manufactured from low carbon sheet
steel and is glass-lined on the inside. In
addition the tank is fitted with a
sacrificial anode as an extra protection
against corrosion. A thick PU-insulation
layer covered in a steel jacket reduces
unnecessary heat loss. When the
appliance is filled with water it
continuously is under water pressure.
As hot water is drained from the tank,
cold water is added immediately. Four
flue baffles have been placed in the flue
tube to improve heat transfer. The flue
gasses pass their heat on to the water
by means of radiation and convection.
The flue gasses are guided to the
chimney via the draught diverter. The
exhaust of the flue gasses is realized
by natural thermal draught (see
drawing 1).
Dead legs on a hot water installation are
undesireable. Where possible they
should be avoided. Where the inclusion
on the system of a dead leg is
unavoidable the following restrictions
should be applied:
-for pipes not exceeding 19 mm.
inside diameter; maximum lengh of
dead leg permitted 12.0 metres;
-for pipes exceeding 19 mm. but not
exceeding 25 mm. inside diameter;
maximum length of dead leg 7.5
metres;
-for pipes with an inside diameter
exceeding 25 mm. maximum dead leg
3.0 metres.

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1.2 Technical safety
equipment
Gas control block
The water heater has been fitted with a
gas control block consisting of a
thermo-electrical pilot flame safeguard,
pilot flame pressure regulator, burner
pressure regulator, a control thermostat
(adjustable between 40°C and 81°C)
and a safety thermostat (90°C). This
gas control block with its simple and
secure control respectively switches
the gas supply to the main burner on or
off.
This gas control block is suitable for
gasses from the first, second and third
gas family. The maximum inlet pressure
is 50 mbar.
Flue down draught safety device
The heater is fitted with a flue gas
blowback safety device. The
functioning of the safety device is
based upon the principle of the Thermal
Reflux Safeguard – TRS for short –
shown in Fig.2.
This TRS can be recognized by the
copper coloured spiral that is fitted to
the lower edge of the draught diverter.
The spiral is connected to a thermostat
by means of a capillary tube. The wiring
of the thermostat must be connected to
the thermocouple circuit.
Drawing 2 - Gas control block with T.R.S. 1) T.R.S.thermostat
2) Sensor T.R.S. thermostat
3) Thermocouple with built-in
interrupter
4) Thermocouple
5) Gas control block
6) Reset button
7) Pilot burner
8) Temperature regulator knob

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It is the aim of the T.R.S. to prevent flue
gasses from the water heater entering
the room where the water heater has
been placed, instead of passing through
the flue to outside atmosphere. The
thermo-couple circuit is interrupted and
the gas supply is disconnected as soon
as the T.R.S. is activated by heating of
the sensor by the hot gasses.
After the cause of the reentry of flue
gasses has been traced the device can
be put back into operation again. In case
of T.R.S. the RESET button has to be
pressed first.
If this failure occurs frequently, this
indicates that the flue suffers from
down draught conditions. We advice
that necessary remedial actions be
carried out by a competent person.
Important
If the water heater is put out of
operation by a failure, this may be
caused by the T.R.S.. If there is a
RESET button on the thermostat, this is
visible because the button rose. The
device can be put back into operation
by pressing the RESET-button.
The T.R.S. should never be put out
of operation. Reentry of flue
gasses to the building could be
harmful and cause poisoning or
death.
Attention:
Instruction addition for installer.
Fitting the Thermal Reflux Safeguard:
1. Remove the two screws from the lid;
2. Position the support (with pre-
assembled TRS) onto the lid;
3. Secure the support, using both
screws;
4. Interconnect the male and female
connectors on the lid.

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1.3 Technical description
1.3.1 Dimensions
These water heaters are only suitable for
a ue tube with minimal the announced
diameter (dimension G).
All dimensions are given in mm. (rounded off on 5 mm)
A 1585 1780
B 1450 1640
D 645 675
E 735 765
G 130 130
K 375 375
M 1505 1685
N 1505 1685
R 285 285
S 1280 1460
1 Cold water inlet
2 Hot water outlet
3 Gas control
4 Drain valve
5 T&P relief valve tapping
Dimensions SCT 75-75 SCT 100-95

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Drawing 3 - Dimensions

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1.3.2 Technical data
Device category: II2H3+
Description Unit SCT 75-75 SCT 100-95
DATA NATURAL GAS G20 - 20 mbar
Nominal load (gross) kW 25.1 26.7
Nominal capacity kW 19.2 20.4
Supply pressure mbar 20 20
Burner pressure mbar 12.5 8.7
Gas consumption * m3/h 2.40 2.50
Diameter main orice mm 3.90 4.50
Diameter pilot orice mm 2 x 0.27 2 x 0.27
Heating time ∆T= 45 K min. 43 55
DATA BUTANE G30 - 30 mbar
Nominal load (gross) kW 24.5 26.0
Nominal capacity kW 19.2 20.4
Supply pressure mbar 30 30
Burner pressure (G30) mbar 30 30
Gas consumption (G30)* m3/h 1,80 1.90
Diameter main orice (G30) mm 2.30 2.35
Diameter pilot orice (G30) mm 2 x 0,16 2 x 0,16
DATA PROPANE G31 - 37 mbar
Nominal load (gross) kW 24.6 26.1
Nominal capacity kW 19.2 20.4
Supply pressure mbar 37 37
Burner pressure (G30) mbar 37 37
Gas consumption (G30)* m3/h 1.8 1.9
Diameter main orice (G30) mm 2.30 2.35
Diameter pilot orice (G30) mm 2 x 0.16 2 x 0.16
GENERAL
Storage capacity litres 265 355
Water connections** - 1 - 11.5 NPT 11/4 - 11.5 NPT
Gas connection - Rp 1/2Rp 1/2
Drain valve - 3/4" - 14 NPT 3/4" - 14 NPT
T&P-plug - 3/4" - 14 NPT 3/4" - 14 NPT
Maximum operating pressure bar 8 8
Weight (empty) kg 117 144
* Gas consumption at 1013,25 mbar and 15 °C
** For a leak proof sealed connection European coupling pieces can be used on the NPT
connection nipples with a pipe thread of ISO 228/1

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2. FOR THE INSTALLER
2.1 Installationinstructions
This water heater must be fitted in a
location which will permit the provision
of an approved flue system and
adequate ventilation.
A service clearance of 15 cm at the
sides and rear of the unit and 60 cm at
the front of the unit should be allowed
for ease of servicing. Adequate
distance must be allowed between the
top of the unit and any obstruction or
ceiling to allow the flue baffle and
anode to be inspected, cleaned or in the
case of the anode replaced if
necessary.
The water heater must stand on a level
surface resistant to heat and with
sufficient strength to support the weight
of the unit when full of water.
This water heater must not be installed
in a bath room, bedroom or in a cup-
board opening on to such rooms. This
water heater must not be installed in
any area where flamable materials are
used or stored.
Insufficient ventilation may give rise to a
risk of fire, explosion or suffocation. If
in doubt consult the national and local
regulations governing the installation of
gas appliances or your local British gas
service department.
2.1.1 Installation
The installation of this water heater
should be carried out by a suitably
qualified competent person. It is a
criminal offence for unqualified persons
to install gas equipment.
Installation should be carried out in
accordance with all local authority and
building regulations, local water
authority and fire regulations and the
following British standards: 5440, 5546,
6644, 6700, 6798 and 6891.
Some chemicals produce vapours which
can cause rapid failure of
thermocouples, burners and storage
tanks if they are drawn into the
combustion air supply.
Therefore if this water heater will be
used to supply hot water to:
-hairdressers,
-dry cleaners
-industrial degreasing processes
or any other area where
compounds containing halogens are
used and stored, care should be
taken that all primary and secondary
air is drawn from outside atmosphere
free of such contaminents.
For further advise contact STATE
WATERHEATERS.
2.1.2 Water connections
STATEWATERHEATERSaresuitable
for connection to vented, unvented and
pumped pressurised systems. In each
case appropriate valves and fittings
should be used to ensure the system
complies with the requirements of the
water by laws, and appropriate building
regulations.
When fitting it is essential the rules of
'good practice' are applied at all stages
of installation.
Vented systems
If the water heater is to be connected to
a cold feed tank or cistern the hot water
supply pipe must include an open vent
which discharges over the cold feed
cistern. The cold feed cistern must have
an actual capacity of greater volume
than the hourly recovery rate of the
water heater(s) which it supplies.The
minimum actual capacity is 50 gallons or
227 litres.

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2.1.3 Gasconnection
The gas supply to this appliance must
be installed in accordance with BS 6891
(1988).
Fit the 1/2" gas supply cock supplied
with this unit immediately before the gas
control block. No heat or soldered joints
should be applied in the vicinity of the
gas control block, as they could cause
damage to the control.
All connections and joints should be
tested for gas soundness with a
suitable leak detector (do not use a
naked flame).
Unvented
ToinstallanSTATEWATERHEATERS
on an unvented cold water supply
system a kit of valves and fittings listed
by the water research centre and
complying with part G3 of the current
building regulations should be used.
Installation should be carried out
generally as shown on the following
diagram. See drawing 4.
STATEWATERHEATERSaretestedto
a maximum pressure of 12 bar and a
maximum working pressure of 8 bar.
1) Gas cock
2) Stop valve
3) Expansion vessel
4) T&P safety valve
5) Non return valve
6) Circulationpump
7) Drain valve
8) Pressure limiting valve
9) Pressure relief valve
A) Gas supply
B) Hot water outlet
C) Cold water inlet
D) Hot wayer outlets
E) Return circulation loop
Drawing 4 - Connection diagram
(unvented system)

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2.1.4 Fluesystem
The water heater should be fitted with a
flue system connected to the draught
diverter. The flue pipe should rise for at
least 50 cm. vertically before the
inclusion of any bends. If a horizontal
run of flue is required this should be
kept to the minimum length possible and
incorporate a rise of 6 cm. per metre of
run. A split clip or flange should be
provided in the flue close to the draught
diverter for ease of servicing.
All flue materials should be corrosion
resistant i.e. stainless steel or
galvanised and must include a tested
and approved terminal to BS 5440 part I.
If the flue passes through any
combustible material measures must be
taken to protect against the possibility of
fire.
All flues must terminate in free air space
approx. 1.5 metres from any vertical
surface of structure i.e. chimney
stacks, roof parapets, etc. If an existing
chimney or flue is to be used this should
be swept clean and be free of debris
before an approved liner is installed and
connected to the water heater.
2.1.5 Draughtdiverter
The draught diverted is fitted with a
temperature sensor to signal the
blowback of flue gases.
Important
The T.R.S. should never be put out of
operation. The reentry of flue gasses
may cause poisoning.

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2.2 Commissioning
Filling the water heater
1. Close the drain tap.
2. Open the cold water tap to the water
heater and open all taps where hot
water can be drained for de-
aeration. The water heater is filled
as soon as cold water flows from all
taps.
3. Close all hot water taps.
Putting into operation
1. Check whether the water-heater
has been filled with water and
whether the gas supply to the water
heater is open;
2. Turn the temperature control knob
clockwise and place the control knob
inthe‘PILOT’-position(✸);
3. Remove the outer door of the
combustion chamber;
4. Keep the control knob pushed-in and
press the piezo-ignitor several times
until the pilot burns (see drawing 6);
5. Keep the control button (✸) pushed-
in for approximately 20 seconds.
After releasing the button the pilot
should remain burning. If the pilot
extinguishes you should wait 5
minutes before repeating the ignition
procedure. The size of the pilot flame
can be adjusted (see also “Pilot
adjustment”);
6. Fit the outer door;
7. Turn the control button to the ‘ON’
( ) position;
8. Place the temperature control button
in the correct position, preferably
position 3 (approximately 60°C). The
appliance will now operate fully
automatically.
Drawing 6 - Operation of the gas
control block

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2.3 Pilot adjustment
The pilot can be adjusted by means of
the regulating screw under the plastic
cover on the right hand side of the gas
control block (see drawing 7).
Turn the screw clockwise to reduce the
gas pressure and anti clockwise to
increase the pressure. Care should be
taken to ensure the pilot covers the
thermocouple element correctly.
2.4 Putting out of operation
1. For short periods of time the control
knob should be turned to (✸); the
pilot keeps burning.
2. For longer periods of time the knob
should be turned to the (●) position;
the pilot is extinguished.
3. Close the gas tap in the supply pipe.
In case of longer interruptions or in
the event of risk of frost it is
recommended to also close the cold
water tap and to drain the appliance
after cooling (open the drain tap; it is
possible to connect a drain hose to
the drain tap; open the nearest hot
water drain point to prevent air
locks). To be able to drain the
appliance completely it should be
disconnected and tilted slightly in the
direction of the drain tap.
2.5 Temperature regulation
The appliance is under water supply
pressure (maximum 8 bar). The amount
of cold water that is added is equal to
the amount of hot water used. The gas
control block automatically regulates the
gas supply. The main burner will ignite
as soon as a reduction in water
temperature is sensed by the
thermostat. The main burner will shut
down as soon as the preset
temperature is achieved.
Position 1 = approximately 40°C
Position 2 = approximately 50°C
Position 3 = approximately 60°C
Position 4 = approximately 70°C
Position 5 = approximately 80°C
At high water temperatures there is
more scale buildup in the appliance. It is
for this reason that it is recommended to
place the temperature control knob in
position 3 as the accumulation of scale
will be reduced. In addition a safety
thermostat has been fitted. This
thermostat completely shuts off the gas
supply if the water temperature
reaches 90°C, also extinguishing the
pilot burner.
Drawing 7 - Setting the pilot

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2.6 Setting the nominal
heat input
The gas control has been factory
preset to the water heater nominal heat
input.
A further check of the burner pressure
should be carried out during the
commissioning of the unit after
installation. The following procedure
should be followed.
1. Remove the protruding cover screw
on the right side of the gas control
block and connect a U-gauge
manometer to the outlet;
2. Put the appliance into operation and
ignite the burner;
3. Check the burner pressure and, if
necessary, reset by means of the
adjusting screw “pr adj” (pressure
adjustment; see drawing 8). To make
this possible the temperature control
knob should be removed by pulling it
straight forward, making the “pr adj”
visible. Turning clockwise reduces
the pressure; turning anti clockwise
increases the pressure. It is
recommended to check the heat
input by means of the gas meter;
4. Turn off the appliance and remove
the manometer hose and replace the
adjusting screw;
5. Relace the thermostat control knob;
6. Put the appliance into operation.
2.7 Converting to another
type of gas
For conversion of the appliance from
natural gas to another type of gas, or
vice versa, it is necessary to exchange
the pilot injector and the main injector.
The conversion may only be executed
by a qualified competent person.
Drawing 8 - Setting the nominal load

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Procedure:
1. Close the main gas tap in the gas sup-
ply;
2. Demount the burner (see “Cleaning”);
3. Replace the injector of the main
burner and the pilot burner with the
correct injectors from the conversion
set (see table above);
4a. Conversion from natural gas to LP-
gas:
- Put the pressure regulation of the
gas control block out of operation.
To do this the temperature
regulating knob should be pulled
straight forward. Next the red
plastic cover that is now visible,
should be removed. Turn the ‘no
pr’ (no pressure regulation) screw
down tight (see drawing 9)
- Remount the burner in reverse
order.
- Open the main gas tap.
Drawing 9 - Conversion to another gas
Unit SCT 75-75 SCT 100-95
G20 G30 G31 G20 G30 G31
Inletpressure mbar 20 30 37 20 30 37
Burner pressure mbar 12.5 30 37 8.7 30 37
Diameter main
injector mm 3.90 2.30 2.30 4.50 2.35 2.35
Diameter pilot
injector mm 2x0.27 2x0.16 2x0.16 2x0.27 2x0.16 2x0.16

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4b Conversion from LP-gas to natural
gas:
-Put the pressure regulator into
operation. To do this the
temperature regulating knob should
be pulled straight forward. Next
the red plastic cover that is now
visible, should be removed. Turn
the ‘no pr’ (no pressure regulation)
screw completely up (see drawing
9).
-Remount the burner in reverse
order.
-Open the main gas tap.
-Set the correct burner pressure
(see table above).
5. If necessary adjust the pilot correctly
(see “Pilot adjustment”).
6. Fit the correct sticker from the
conversion set on the appliance so
that it is clear that the appliance has
been converted and on which gas
the appliance operates.
2.8 Maintenance
To ensure safe and efficient operation
of the water heater it is recommended
that it is cleaned and serviced at least
once a year by a qualified competent
person.
2.8.1 Sacrificial anode
The life cycle of the anode is
determined by the quality and the
quantity of the water flowing through
the apparatus. It is therefore
recommended that the anode be
inspected and replaced if necessary at
least once a year.
1. Close the stop cock in the cold
water supply pipe;
2. Open the nearest hot water tap in
order to allow the pressure to drop
from the water heater and the pipes;
3. Slacken the anode with a fitting
wrench;
4. Check the anode and replace it if it
has been reduced in diameter by
60% or more at any point on its
length;
5. Check for water leaks.
If it is necessary to replace the anode it
should always be replaced by one of
the same type.
The type of anode required can be
determined on the basis of the type of
the appliance and the serial number.

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2.8.2 Cleaning
1. Close the gas supply and demount
the burner after it has cooled down.
2. Disconnect the burner, pilot pipe and
thermo couple from the gas control
block (see drawing 10).
3. Remove the complete burner
assembly.
4. Clean the burner with a soft brush.
5. Check the pilot burner and clean it if
so required.
6. Check the combustion chamber, flue
tube and flue baffle and clean these
if required.
7. Re-mount in reverse order. Tighten
the thermo couple connection on the
gas control block hand tight and
tighten it further with a wrench to a
maximum of 1/4 turn as it only needs
to make contact.
After cleaning of the pilot- and main
burner the operation of these should be
checked. If necessary the burner
pressure of the main burner should be
reset.
2.8.3 Decalcification
Formation of lime scale depends on the
quality and quantity of the water used.
In addition higher water temperatures
lead to more deposit in the appliance. A
temperature setting of 60°C is
recommended in order to keep the
calcification at a low level.
Decalcification should be attempted with
the proper means. For extensive
information a decalcification instruction
is available.
2.8.4 Spare parts
To be able to order spare parts it is
important to note the type of appliance
as well as the serial number of the
appliance. Based on this information the
data concerning the spare parts can be
determined.
Drawing 10- Mounting burner-set

20
2.9 Inlet combination
Not applicable in U.K. and Ireland.
2.10 Fault finding
In case of failure the following should
be checked.
Safety thermostat
All appliances have been fitted with a
safety thermostat that shuts off the gas
supply when the water temperature is
too high. The safety thermostat remains
activated until the water temperature
drops below the safety temperature.
The water heater must be reignited
manually. The regulation thermostat
should be set to a lower water
temperature. If the pilot is extinguished
repeatedly at higher temperatures than
normal, this indicates that the safety
thermostat is operating.
Flue down draught safety device
If the flue tube safety device has
switched off the appliance, the
appliance can be put back into operation
through the normal procedure. If the flue
tube safety device repeatedly puts the
appliance out of operation then this
points to problems with the flue. The
only remedy is to determine the cause
of the problem (for instance a blocked
chimney) and to solve the problem.
Hot water temperature too low
1. Check the setting of the temperature
control knob;
2. Check whether the pilot is alight. If
necessary ignite (see “Putting into
operation”);
3. Check whether there are any leaks
or open taps;
4. Is the gas supply adequate? Check
and correct if necessary;
5. Perhaps the hot water consumption
is higher than was originally
calculated;
6. Check whether the cold water inlet
has been correctly connected;
7. Check the thermostat sensor for
scale build up.
Hot water temperature too high
Check whether the control
thermostat is set too high.
Possible water leakage
1. Check whether the drain tap is fully
closed;
2. Check whether all water
connections are water tight;
3. Check whether the possible water
leakage could be caused by
condensation.
2.11 Gas smell
Warning
Immediately shut the main gas tap. Do
not light any fire or switch on any lights,
do not use any electrical switches or
alarm bells. Open windows. Thoroughly
inspect all gas connections and, if the
gas smell persists, alert the local gas
company and/or your installer.
2.12 Condensation
If the appliance is filled with cold water
or if the hot water consumption is very
high, condensation of flue gasses will
occur on the cold surfaces of the
combustion chamber and the flue tube.
The water drops will fall on the burner
and cause a sizzling noise. This is a
normal phenomenon that will disappear
as soon as the appliance reaches its
normal operating temperature.
IMPORTANTWARNING
The applicance should NEVER be
taken into operation with a closed
cold water supply!
Provision should always be made
for expansion.