A.O. Smith EQ 280 G Guide

WATERSTORAGEHEATERS
UNITED KINGDOM / IRELAND
MODELS EQ 280 G
EQ 380 G
INSTALLATION- AND USER
INSTRUCTION

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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.
A.O.SMITHACCEPTSNORESPONSIBILITYFORWARRANTY,SERVICEAND/OR
PRODUCTLIABILITYINCASEOFUNAUTHORIZEDALTERATIONS,PRODUCT
MODIFICATIONSORREPAIR.

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CONTENTS PAGE
1. General. ......................................................................................................... 4
1.1 -Description of the appliance .......................................................................... 4
1.2 -Technical safety equipment ........................................................................... 6
1.3 -Technical description..................................................................................... 8
1.3.1 -Dimensions .................................................................................................... 8
1.3.2 -Technical data ............................................................................................. 10
2. Forthe installer.......................................................................................... 12
2.1 -Installation instructions ................................................................................ 12
2.1.1 -Installation .................................................................................................... 12
2.1.2 -Water connection ........................................................................................ 12
2.1.3 -Gas connection ........................................................................................... 13
2.1.4 -Flue system ................................................................................................. 14
2.1.5 -Flue down draught safety device................................................................ 14
2.2 -Commissioning ............................................................................................. 15
2.3 -Pilotadjustment ............................................................................................ 16
2.4 -Putting out of operation................................................................................ 16
2.5 -Temperature regulation................................................................................ 16
2.6 -Setting the nominal heat input ...................................................................... 17
2.7 -Conversion procedure................................................................................. 17
2.8 -Maintenance ................................................................................................ 19
2.8.1 -Sacrificial anode .......................................................................................... 19
2.8.2 -Cleaning ....................................................................................................... 19
2.8.3 -Decalcification ............................................................................................. 20
2.8.4 -Spare parts.................................................................................................. 20
2.9 -Inletcombination .......................................................................................... 20
2.10 -Fault finding ................................................................................................. 20
2.11 -Gassmell ..................................................................................................... 21
2.12 -Condensation............................................................................................... 21
2.13 -Important warning........................................................................................ 21
3. For the user. ............................................................................................... 22
3.1 -Commissioning ............................................................................................. 22
3.2 -Use .............................................................................................................. 22
3.3 -Putting out of operation................................................................................ 22
3.4 -Fault finding ................................................................................................. 23
4. Guarantee. .................................................................................................. 24

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1. GENERAL
1.1 Descriptionoftheappliance
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 has 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) 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) Steeljacket
10) Flue baffle
11) Sacrificial anode
12) Drain tap
13) Atmospheric burner
14) Pilot light burner with
thermocouple
Drawing 1 - Cross-section of the
appliance

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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 30°C and 71°C)
and a safety thermostat (82°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.
Thermal Reflux Safeguard
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 Technicaldescription
1.3.1 Dimensions
These water heaters are only
suitable for a flue tube with minimal the
announced diameter (dimension G).
All dimensions are given in mm. (rounded off on 5 mm).
Dim. EQ280 EQ380
(ziefig.3)
A1585 1780
B1450 1640
D645 675
F730 765
G130 130
K390 390
L375 385
M1505 1685
N1505 1685
R285 275
S1280 1460
V410 410
1Cold water inlet
2Warm water outlet
3Gas control block
4Drain tap
5T&P relief valve tapping

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Drawing 3 - Dimensions

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1.3.2 Technical data
Device category: II2H3+
DESCRIPTION unit EQ280 EQ380
DATANATURALGAS G20-20 mbar:
Nominalheatinput(lowervalue) kW 22.6 24.0
Nominalpower kW 19.2 20.4
Inlet-pressure(G20) mbar 20 20
Burnerpressure(G20) mbar 12.5 8.7
Gasconsumption(G20)*m3/h 2.4 2.5
Diametermainorifice(G20) mm 3.90 4.50
Diameterpilotorifice(G20) mm 2X0,27 2X0,27
Warming-uptime∆T=45Kmin. 56 61
DATABUTANE G30- 30mbar:
Nominalheatinput(lowervalue) kW 22.6 24.0
Nominalpower kW - -
Inlet-pressure(G30) mbar 30 30
Burnerpressure(G30) mbar 30 30
Gasconsumption(G30)* kg/h 1.8 1.9
Diametermainorifice(G30) mm 2.30 2.35
Diameterpilotorifice(G30) mm 2x0.16 2x0.16
Warming-uptime∆T=45Kmin. - -
DATAPROPANEG31-37mbar
Nominalheatinput(lowervalue) kW 21.1 22.9
Nominalpower kW - -
Inlet-pressure(G31) mbar 37 37
Burnerpressure(G31) mbar 37 37
Gasconsumption(G31)*kg/h 1.6 1.8
Diametermainorifice(G31) mm 2.25 2.35
Diameterpilotorifice(G31) mm 2x0.16 2x0.16
Warming-uptime∆T=45Kmin. - -

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DESCRIPTION unit EQ280 EQ380
GENERAL
Storagecapacity litres 265 355
Waterconnections** -1" - 14 NPT 11/4" - 14 NPT
Gasconnection -ISO 7/1Rp 1/2ISO 7/1Rp 1/2
Draintap -3/4" - 14 NPT 3/4" - 14 NPT
Anode -3/4" - 14 NPT 3/4" - 14 NPT
T&P-plug -3/4" - 14 NPT 3/4" - 14 NPT
Maximumworkingpressure bar 8 8
Emptyweight kg 153 178
*Gasconsumptionat1013,25mbarand15°C
** Foraleak-proofsealedconnectionEuropeancouplingpiecescanbeusedontheNPT-connectionnippleswithapipethread
ofISO228/1

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2. FORTHEINSTALLER
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
cupboard 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 depart-
ment.
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 A.O.
SMITH.
2.1.2 Water connections
A.O. Smith water heaters are
suitable 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.
Unvented
To install an A.O. Smith water
heater 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

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the current building regulations should
be used. Installation should be carried
out generally as shown on the following
diagram. See drawing 4.
A.O. Smith water heaters are tested
to 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
Drawing 4 - Connection diagram
(unvented system)
2.1.3 Gas connection
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.
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

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All connections and joints should be
tested for gas soundness with a
suitable leak detector (do not use a
naked flame).
2.1.4. Flue system
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 horizon-
tal 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 Draught diverter
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. Check the burner pressure setting
(see drawing 9) and, if necessary,
adjust this in accordance with the
technical data (see page 10).
9. Place the temperature control button
in the correct position, preferably
position 4 (approximately 60°C). The
appliance will now operate fully
automatically.
Drawing 6 - Operation of the gas
control block

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2.3 Pilotadjustment
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.
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.
2.4Puttingout 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 30°C
Position 2 = approximately 40°C
Position 3 = approximately 50°C
Position 4 = approximately 60°C
Position 5 = approximately 70°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 4 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 82°C, also extinguishing the
pilot burner.
Drawing 8 - Setting the pilot

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2.6 Settingthe 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 9). 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 Convertingtoanothertype
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 9 - Setting the nominal load

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Unit EQ280 EQ380
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
Diametermain mm 3.90 2.30 2.25 4.50 2.35 2.35
injector
Diameterpilot 2x 2x 2x 2x 2x 2x
injector mm 0.27 0.16 0.16 0.27 0.16 0.16
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
10).
-Seal this setting with lacquer.
-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.
Procedure:
1. Close the main gas tap in the gas
supply.
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).
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. Turn the ‘no pr’
(no pressure regulation) screw
down tight (see drawing 10).
-Seal this setting with lacquer.
-Remount the burner in reverse
order.
-Open the main gas tap.

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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
Drawing 10 - Conversion to another gas
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.
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 11);
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.

20
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.
2.9 Inletcombination
Not applicable in U.K. and Ireland.
2.10 Faultfinding
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.
Drawing 11- Mounting burner-set