A.O. Smith Gen 8 Digital User manual

Mini Water Heater
Gen 8 Digital
EWH-40MINI2
User Guide

About A. O. Smith
Established in 1874, the A. O. Smith Water Products Company is a global leader in innovative water
technologies. With 21 fully-owned plants, they are currently the largest water heater manufacturer in the
world.
Over the years, A. O. Smith has gained the respect and support of homeowners, contractors, architects
and specifying engineers in over 60 countries by providing energy efficient hot and clean water
solutions.
What’s in the box?
2

Contents
Specifications ........................................................................................... 5
Safety Features ....................................................................................... 6
Product Features ...................................................................................... 6
Installation ................................................................................................. 9
Directions For Use .................................................................................... 13
Maintenance Instructions ....................................................................... 17
Troubleshooting ....................................................................................... 18
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Read Before Use
Before installation and use of this device, please read this manual carefully and keep it ready for future
reference.
Engage an experienced water heater installer. A. O. Smith and AOS Bath will not be held liable by any
damages or piping leakages caused by incorrect installations.
This heater is suitable for residential use. Any attempts to use it for commercial purposes will reduce the
heater lifespan. Once the heater has been installed, owners should run checks every 6 months and the
system should undergo maintenance every 3 years. If there are any operational irregularities, please
discontinue use of the heater immediately and call our company hotline.
Before any instances of heater repair and maintenance, users should disconnect the power supply. Any
modifications and repairs should only be handled by company approved technicians.
Heaters may cause serious scalding. Mix hot with cold water before showering or taking a bath.
If heater suffers from dry heating, any resultant steam and hot water may cause serious scalding. As a
result, users should ensure that the heater tank is always full of water. If dry heating occurs, immediately
cut off electrical & water supply and stop using the heater. Call our company service hotline and wait for
our approved technicians to do the necessary checks and repair.
For safety issues, do not change any of the settings of the pressure relief valve or temperature pressure
relief valve. Ensure all blockages are clear and install a drainage pipe to allow the overflow water to be
discharged into a floor drain.
Water produced by the heater is not potable and should not be consumed.
Any circuits, gauges, circuit breakers and wiring used for the heater must meet current ampere
requirements and be checked by approved technicians. Do not use damaged circuitry or an outdated,
loose, unstable power outlet for the heater. This will cause electrical shocks, fuses, fires, etc.
Heater electrical connections must be used in tandem with a dedicated power source located at a dry
area. Do not handle electrical points with wet hands. This may cause electrocution or physical damage to
self.
A white translucent colour to the water produced by the heater is considered normal. This is due to the air
pockets or foam caused by the pressure of dissolved air in water after heating.
Note: Incomplete compliance of this manual’s contents may cause fires, financial or property losses,
personal harm or death.
Warning: This is an electronic appliance and must be used with reliable connections.
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Specifications
Specifications
Rated volume (L)
40
Power (kW)
4.0
Voltage/Frequency (V/Hz)
220/50
Temperature range (
°C) 35-75±5
Rated water pressure (
MPa) 0.8
Max
-min inlet water pressure (MPa) 2.0/3.0
Inlet/outlet connection (inches)
½
Waterproof grade
IPX4
A. O. Smith reserves the right to
make product changes or
improvements at any time
without notice.
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Dimensions
Length (mm)
880
Width (mm)
340
Height (mm)
350

Safety Features
Thermal Cut Out
The water heater employs a thermal cut out. In case any fault occurs and the water
temperature exceeds the highest preset limits, the switch rapidly cuts off the live and
neutral line for user’s safety.
Pressure Relief Valve
The safety valve will relive pressure automatically through droplets of water when
the system exceeds the rated pressure.
Product Features
Intelligent Maintenance Monitor (IMM)
IMM helps to prevent corrosion of the internal heater tank. The intelligent active
system releases protective ions into the tank, neutralizing aggressive corrosive ions in
the water.
Automatic Energy Saver (AES) (Patent ZL00112584.2)
The AES memory chip records up to 21 days of usage habits and automatically heats
water before users take a bath. During off peak periods, the heater goes into
energy saving mode.
6 MAX heating technology produces thrice as much hot water as a conventional
electric heater without consuming more energy.
6 MAX Heating (Patent ZL200820185859.4)
6
IMM

Blue Diamond Dual Elements (Patent ZL200510037670.1)
This water heater has two patented Blue Diamond heating elements which increase
heating efficiency by up to 50%.
Touch Control Panel
Access all modes of the water heater or reduce your water heating bills by turning
down your heater thermostat from the control panel.
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Hot Water Display
Temperature sensors in the heater provide a visual display of hot water from the
control panel.
Instant Heating (Patent ZL200820185859.4)
Intelligent sleep mode
The heater goes into power-saving mode after 3 minutes of inactivity.
The latest instant technology allows users to get hot water from an unheated tank
immediately, without consuming more energy.
Programmable Timer
The timer powers up the heater for you so you don’t have to turn it on manually. It
also switches your heater to energy saving mode when not in use.
Wireless remote
Program your heater with the wireless remote. The keys are identical to those on
the touch screen panel.

3 Year Full Warranty
With the highest manufacturing standards and strict quality control, we assure users
durability with a 3 year full warranty on the whole unit, the longest warranty in
Singapore.
3years
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High Efficiency Insulation
A polyurethane foam insulating layer without freon is used, which provides a good
insulation and reduces heat loss effectively.
Blue Diamond Tank (Patent US6303183)
Patented A. O. Smith Blue Diamond Tanks provide superior durability. The longest
lasting Blue Diamond tank in the world was used for 52 years.

Installation
CAUTION:
•Please wait for 30 minutes before using the heater for the first time.
•The heater should only be connected to a power source after a full installation which ensures
secure mounting, piping, wiring and filling of the tank with water.
•To prevent injuries from lifting heavy equipment, the water heater should be installed by at least
2 persons.
•The water heater must be installed by a qualified personnel.
Location
This water heater should be installed at a location that is close to a power source, floor drain and
water supply. As the water heater is in use, water may be discharged from the pressure relief valve,
so there must be a floor drain near the heater. When installing the water heater, be sure the water
inlet and outlet pipes are at the bottom of the heater. The system must not be installed vertically.
Mounting Procedures and Precautions
The surface for installation must be capable of supporting at least four times the weight of the water
heater when filled with water. If the water heater is not installed on the bearing wall or is mounted
on hollow brick wall, corresponding protective measures must be provided.
This water heater must be installed with the fixing accessories provided. The heater must be hung on
accessories which are fixed firmly or else the heater may dislodge and serious injuries will result.
Mounting Guidelines
Before drilling, ensure the right side of the
heater is at least 300mm away from the wall
so as to allow for easy maintenance access. If
the heater is installed above a false ceiling,
ensure a 500 x 500mm service access directly
below.
Use an electric drill with a Ø12mm drill bit to
drill two holes 100mm in depth. The holes must
be level. The space between the two holes
should be 380mm.
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Fit a plastic drill bit into the drilled holes and slowly twist the screws into the holes with an allen key.
Do not over tighten as it may cause the drill bits to break.
Place the screws through the square, top portion of the mounting plates and mount the heater on the
plates. Give the heater a firm downward tug to ensure the screws are lodged firmly against the
brackets.
CAUTION:
•The mounting accessories provided can only be used for solid walls, as shown in the drawing
above. Improper installation may cause the water heater to dislodge.
10
correct installation incorrect installation100mm depth
Electrical Connection
This water heater must be permanently connected to the electrical supply through a double pole
switch having a contact separation of at least 3mm in all poles incorporated in the fixed wiring. The
insulation of the fixed wiring must be protected by an insulating sleeving with a temperature rating
of at least 80°C.
Ensure the water heater is reliably grounded. The earth wire must be longer than the current carrying
conductors. The maximum power of this water heater is 5000W, hence a single dedicated power
supply circuit is proposed. On 5kW mode, the heater must be connected to a circuit of rated current
no less than 32A. If the wire diameter is 2.5m², the system must operate in 4kW mode.
Switching wattage modes
1. Use screwdriver to remove power adjustment switch cover
2. Turn rocker switch to ’0’ position as shown in the figure
3. Close cover and tighten screws to secure

Water Inlet and Outlet Connection
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9
Plumbing Connection
The heater comes with a relief valve. Connect the valve to the inlet (marked in blue). The arrow on
the valve should be in line with the direction of the water flow. The storage heater must be
permanently connected to the water mains and the use of a hose set is prohibited. The hot water pipe
is connected to the water outlet (marked in red).
The safety valve must be connected to a PVC discharge tube, mounted downwards to a nearby floor
drainage in a frostless environment. The pipes should not be blocked. The relief valve is to be
operated regularly to remove lime deposits and to verify that it is not blocked. If the water pressure
of the inlet pipe approaches or exceeds the relief limit (0.80 MPa) of the safety valve, the valve will
relieve pressure automatically. Refer to the following diagram for the pipe connection.
We recommend the use of a double check valve assembly for the installation of the water heaters.
The double check valve assembly is a safe and effective measure for preventing backflow and back-
siphonage of water from the water heaters through the inlet pipe.
CAUTION:
•Apply proper sealant to the pipe joints to prevent leakage. Do not over-tighten the safety valve
to avoid damage.

Remote Control Installation
For convenience, the remote control may be
installed on a wall near the water heater.
Keep the remote control dry.
Remote Control Batteries
•Insert coin into slot and twist
counterclockwise to open the battery cover
•Use a CR2025 battery. The ‘+’ side should
face upwards
•Insert coin into slot and twist clockwise to
close the battery cover
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Front cover
Filling the Tank
After all the pipes are connected, open the discharge valve of the water heater and then the feed
valve. Fill the water heater with water and exhaust the air till a uniform water stream flows out of the
hot water outlet. This indicates that the water heater has been filled up. Close the hot water
discharge valve and check all connections for any leakage. If leakage occurs, empty the water tank,
repair the leaked connection and then refill the heater with water. Do not close the feeding valve
during the filling of water.

Directions For Use
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CAUTION:
•Before using the water heater, ensure it is filled with water and that the power plug has been
connected properly.
1. Initial power up
During the initial power up, all screen
indicators on the control panel will light
up momentarily (2 seconds). After this, the
water heater will enter standby mode.
2. Power on/off
Press the power button to turn the water heater on.
The system is currently operating on default settings.
The actual temperature and set temperatures are
displayed and if the actual water temperature in
the tank is lower than the preset temperature,
heating begins and the heating indicator lights up.
The default settings are:
•Power: 4000W
•Time: 12:00
•Thermostat: 70°C
If the water heater encounters a power outage,
all settings will revert to default settings.
3. Setting the temperature
The water heater can simultaneously display both the actual temperature and set temperature. The
actual temperature measures the average internal tank water temperature and the preset
temperature is the user defined thermostat setting.
Press the “
!
” the “
"
” buttons to adjust the thermostat. The set temperature will blink while being
adjusted. Holding down the adjustment buttons will cause the temperature to increase or decrease
continually. The thermostat has a range of 35°C to 75°C.
IMM indicator Heating indicator
Maintenance indicator Power
After initial power up

4. Setting the clock
In ‘clock’ mode, hold down the ‘Program’ button for 3 seconds
till the time on the screen flashes. Press the “
!
” the “
"
”
buttons to set the hour, then press the ‘Program’ button again
to confirm the hour. Similarly, use the “
!
” and“
"
” buttons to
set the minute. Holding down the adjustment buttons will cause
the digits to increase or decrease continually. Press the
‘Program’ button to confirm the minute. At any point after 16
seconds of inactivity, the system will exit setting mode and the
time at that point will be saved.
Clock mode, where ‘clock’
indicator is lit
5. Setting the first timer
Users can set a timer to specify when water is to be heated and when the heater will go into energy
saving mode. If users choose not to activate the timer function, toggle the ‘Program’ button until the
‘Timer’ indicator light goes on.
Before setting the timer, ensure the clock is adjusted to the right time. Note that the timer start time is
set first, followed by the end time. Toggle the ‘Program’ button till the ‘Timer’ indicator is lit, then
press and hold down the ‘Program’ button for 3 seconds till the time on the screen flashes. You are
now adjusting the timer start time. Use the “
!
” and “
"
” buttons to make 30min increments or
decrements. Press ‘Program’ to finalize the start time and to begin setting the end time. When done,
press ‘Program’ to confirm.
If the timer is set from 20:30 – 22:00, the setting panels should look like these:
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Timer start time Timer end time
6. Setting the second timer
The second timer is an added feature that can only be set between the hours of 21:00 – 08:00. The
directions for setting the second timer are the same as setting the first timer. The difference is, to enter
the setting mode, press (but do not hold) the ‘Program’ button while the ‘Timer’ indicator light is off.
Note: None of the timers will work if AES is activated.

8. MAX and instant hot water
The MAX function is an A. O. Smith technology that allows users to get consistent hot water for long
periods of time. This function will automatically activate if there is an unexpected surge in demand
for hot water. The ►► indicator will light up when MAX is activated.
In climates where incoming water temperature is 30ºC, the water heater can produce hot water at a
rate of 8 lit/min instantaneously.
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7. Automatic Energy Saver (AES)
Press the ‘AES’ button to activate or deactivate AES. The AES indicator will be lit if active.
AES is a memory chip that records up to 21 days of your family’s usage habits. It is an automatic
timer which preheats water according to your family’s needs and sends the heater into energy saving
mode at required intervals, saving energy by minimizing thermal loss.
Note: None of the timers will work if AES is activated.
10. Intelligent sleep
The water heater’s display panel goes into sleep mode after 3 minutes of inactivity. Press any key to
‘wake’ the heater to view the full display.
Panel in ‘wake’ mode Panel in ‘sleep’ mode
9. Hot water display
The heater can display the amount of hot water available. The five light blocks on the left of the
panel are an indication of the quantity of hot water in the tank.
Red – hot
Orange – warm
Green - cool

11. Intelligent Maintenance Monitor (IMM)
IMM is activated the minute the system is connected to
a power source and the ‘IMM’ indicator lights up on
the panel. Press the key to commence a water ion
quality test. There are two results:
P1: corrosive ion count is low
P2: corrosive ion count has increased to 90%
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12. System reset
Press and hold the ‘AES’ and ‘Program’ buttons for 8 seconds to revert to factory state. When the
system is reset, all screen indicators will glow for 2 seconds and the system will reboot.
13. Electrical safety
In the event of any circuitry issues, the system will cut off
power and prompt for a reset. The display panel will
go blank and the ‘E-fault’ indicator will appear. If this
happens, contact your local authorized dealer to
perform a thorough check.
When corrosive ion count reaches 98%, the indicator will flash on the panel.
Users will be prompted to contact a qualified AOS service personnel to change their depleted
anode rod and perform a tank flush. Tank lifespan will be prolonged when the corrosive ions are
neutralized.
Water ion quality test result
Circuitry issues, E-fault indicator
14. Pressure relief valve inspection
The pressure relief valve is a safety device installed to protect the tank against excessive pressure
build up. The valve relieves pressure when it exceeds 0.8MPa in the form of intermittent water
droplets.
Users should check the valve every 6 months by lifting the handle on the valve to discharge any
calcium carbonate deposits. If water does not discharge from your valve, please contact your local
authorized dealer.
15. Remote controller
The functions on the remote controller correspond with the buttons on the touch screen panel of the
system. The recommended distance for usage of the remote is 4 meters. Install the batteries before
use and change the batteries every 18 months.

Maintenance
If the water heater needs to be serviced, close the water inlet valve, then open the drain valve.
Rotate the handle of the relief valve, release the nut connected to the water outlet joint of the inner
tank and drain the water from the discharge pipe.
It is recommended that the system undergo a safety maintenance every 3 years and the tank be
flushed every 6 years to remove sediments which may have built up during operation. The tank
flushing procedure is as follows:
1. Disconnect the power.
2. Screw off the relief valve and remove the internal water inlet pipe of the water heater.
3. Connect the water outlet pipe connection of the water heater to the tap water pipeline and fill
water from this end. The water inlet pipe connection is connected to floor drain by pipes.
Discharge water from this end.
4. Open the water inlet valve to get the maximum tap water flow and flush the tank till the drained
water from the tank becomes clean.
5. Connect the water inlet and outlet pipes again and put the water heater to use after a leakage
test.
CAUTION:
•The drained water might be very hot and may scald.
Maintenance Instructions
DECLARATION: Only an A. O. Smith authorized service personnel may maintain and repair this
water heater. Improper methods could result in serious injury or property damage.
WARNING -Electric shock: Before repairing the water heater, be sure to disconnect the water
heater from the power source.
CAUTION: Prior to repair works, please refer to the troubleshooting chart.
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Troubleshooting
Problem Possible causes Corrective action
Display is off
No hot water
1. No power to heater
2. No power at electric socket
3. Failure in control circuit or
internal wiring
1. Switch on power to heater
2. Check power socket
3. Contact local authorized
dealer
Display is off
High water temperature
1. High temperature limit switch
tripped
2. Electrical circuit failure
Switch off power supply and
contact local authorized dealer
Display on, no hot water Heating element or internal circuit
failure
Contact local authorized dealer
Leaking from tank Leaking tank or components Switch off power supply and
contact local authorized dealer
Dripping from pipe joints Unsealed joints Reconnect pipes of the water
heater and be sure to use
sealant
Display “E0” Blue wire of two-core terminal
open circuit or short circuit
Contact local authorized dealer
Display “E1” Red wire of two-core terminal
open circuit or short circuit
Contact local authorized dealer
Display “E2” Black wire of two-core terminal
open circuit or short circuit
Contact local authorized dealer
Display “E3” White wire of two-core terminal
open circuit or short circuit
Contact local authorized dealer
Display “EH” High temperature Contact local authorized dealer
Display “EL” Low voltage protection Resume use when voltage is
normal
Display “EA” Relay circuit issue Switch off power supply and
contact local authorized dealer
Display ‘E-fault’ External grounding fault Switch off power supply and
contact local authorized dealer
Display ‘ ‘ Anode needs to be replaced Contact local authorized dealer
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CAUTION:
•Before installing the heater, ensure that the power source and wires are suitable
•The heater should be earthed reliably. Ensure the earth wire is not in contact with the neutral wire
or any pipes
•Once the temperature has been set and the relief valve installed, end users should not alter the
installation location or tamper with the relief valve
•Hot water over 50°C will scald. Always test the water temperature by mixing it with cold water
before coming into contact with it.
•This appliance is not intended for use by persons (including children) with reduced physical,
sensory or mental capabilities or lack of experience and knowledge, unless they have been
given supervision or instructions concerning use of the appliance by a person responsible for their
safety.
•Children should be supervised to ensure that they do not play with appliance.
Wiring Diagram