Midea MWH-38P3, MWH-38P3-RS, MWH-38P5 Instruction Manual
Instant Electric Water Heater
The diagram above is just for reference. Please take the
appearance of the actual product as the standard.
Instruction Manual
For Model: MWH-38P3
MWH-38P5
MWH-38P3-RS
Thank you very much for purchasing our water heater.
Before installing and operating your water heater, please
read this manual carefully and keep it for future reference.
1
TABLE OF CONTENTS
TITLE PAGE
1.Cautions ...........................................................................................................................(2)
2.Product introduction .........................................................................................................(3)
3.Unit installation .................................................................................................................(7)
4.Methods of using ............................................................................................................(10)
5.Maintenance................................................................................................................... (11)
6.Troubleshooting.............................................................................................................. (12)
Sincerely thank you for selecting our electric water heater. Please read this manual carefully
before use; correctly grasp the methods for installation and use of this electrical water heater, to
make full use of its excellent performances. Please do preserve the instruction manual for future
reference.
2
This water heater is for household, and it can be installed wherever place that need hot water.
Plug is not used for this water heater; this water heater must be connected directly with power
switch that comes with leakage-protection. Please distinguish live line (red/brown), neutral line
(blue) and earth line (green/yellow) during installation.
Do check whether the amperes of the household wiring enough before installation, and
dedicated circuit must be used when installation.
Before installing this water heater, check and confirm the earth electrode on the socket is reliably
earthed, without electricity.
The hot water from the water heater may cause scald, please test the temperature of the hot
water before use.
The distance between water heater installed and water output should be as nearby as possible
to avoid loss of heat.
The electric water heater may be damaged if the water hardness is too high. To ensure longer
product lifespan, please install and put it into use on condition that the local water hardness is
less than 450mg/L (CaCO3)
In time of lightning/thunder, switch “Off” the Miniature Circuit Breaker (MCB) in advance to
protect the water heater against possible damage.
Inspection on the built-in ELCB (once a month) to avoid a hazard to users such as damage to
property, serious injury or death.
Do cut-off power supply before any maintenance. Any maintenance or adjustment towards this
product by non-professional is highly prohibited.
The damage power cord must be replaced by a good power cord provided by the manufacturer,
and the replacement should be done by a qualified technician or engineer or professionals of
the similar products.
In order to avoid a hazard due to inadvertent resetting of the Earth Leakage Circuit Breaker
(ELCB), this appliance must not be supplied through an external switching device, such as timer
or connected to a circuit that is regularly switched “On” and “Off” by the utility.
Water heater is equipped with adjustable flow capacity safety valve. For safety use, please do
not change its installation location and do not block its water outlet.
For any improper installation and incorrect operation of this product, our company will not be
liable for any responsibility.
This water heater can be used for other purpose, eg. Washing hands, dishes or foods, and so on.
(Multi directional water supply is not available).
When the shower is used by someone such as child, old person, sick person and physical
handicapped person, the concern person is kindly requested to pay attention and check the
shower temperature by using hand from time to time.
The heater must be permanently connected to the electricity supply, direct from the consumer
unit via a double poles linked switch with a minimum contact gap of 3mm in both poles. The
switch must be readily accessible and clearly identifiable and out of reach of person using a fixed
bath or shower. The wiring must be connected to the switch without the use of a plug or socket
outlet.
To prevent personal injury, injury to others and property damage, the instructions below must be
followed. Incorrect operation due to failure to follow instructions will cause harm or damage.
Installation must be carried out by a qualified personnel and in compliance to the local authority
regulations.
WARNING
Special Cautions
The water heater should be earthed before use. Please ensure that the resistance of
household earth wire is <4Ω. Using water heater without earthed is highly prohibited.
!
1. CAUTIONS
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2. PRODUCT INTRODUCTION
2.2 Parts Identification
Terminal block
DC pump board
Indicator light board
Key board
Silicon control
DC pump
Flow sensor
Marker for
water inlet
Water inlet
Wire pressing board
Thermal
cut out
Main control board
Heating
elements
assembly
Stainless
steel circlip
Temperature
sensor
Marker for
wateroutlet
Water outlet
Red Blue
PRODUCT STRUCTURE FOR MWH-38P3 & MWH-38P3-RS
2.1 Technical Performance Parameters
Model
Rated Voltage
Rated Frequency
Rated Power
Rated Current
Dia. Of Wire Code
Air Switch
Rated Pressure
Minimum Flow Rate
Minimum Pressure
Maximum Pressure
Protection Class
Water Proof Class
Products Size
Knob Quantity
MWH-38P3
MWH-38P3-RS
MWH-38P5
3800W
16A
1.5mm²
≥20A
I
240V~
50Hz
0 MPa
2 Liters/minute
0.02 MPa
0.3 MPa
IP25
230×406×102 mm
2
3800W
16A
1.5mm²
≥20A
1
4
Main control board
Terminal block
Indicator light board
Key board
Silicon control
Flow sensor
Marker for
water inlet
Water inlet
Wire pressing board
Thermal
cut out
Heating
elements
assembly
Stainless
steel circlip
Temperature
sensor
Marker for
wateroutlet
Water outlet
Red Blue
PRODUCT STRUCTURE FOR MWH-38P5
2.4 Internal Wire Diagram
WIRING DIAGRAM FOR MWH-38P3 & MWH-38P3-RS
Indicator Light
And
Key Board
Thermal Cut Out
L
N
E
Red
Blue
Yellow/Green
Temperature
Adjusting Board
Pump Adjusting Board
Heating Elements
Silicon Control
Main Control Board
Relay
Relay
Flow Sensor
Temperature Sensor
Terminal Block
ELCB
CN1
CN3
CN5
CN4
PE
CN2
CN1
CN2
CN1
CN4
CN2
CN3
G
T1
T2
DC Pump Board
DC Pump
3.1 Installation Instruction
3.2 Power Cord Installation
Check the capacity of power circuit;
Power cord installation;
Water heater installation;
Plumbing connection;
Power supply connection;
①
②
③
④
⑤
Water Supply.
Step 1 Step 2
⑥
3. UNIT INSTALLATION
Remove the screws at the bottom of the unit. Lift
up the Main Switch Knob and Power Knob to
make it free. Remove the front plate gently.
Remove the power cord wire pressing plate and
keep the screws.
5
WIRING DIAGRAM FOR MWH-38P5
Indicator Light
And
Key Board
Thermal Cut Out
L
N
E
Red
Blue
Yellow/Green
Temperature
Adjusting Board
Heating Elements
Silicon Control
Main Control Board
Relay
Relay
Flow Sensor
Temperature Sensor
Terminal Block
ELCB
CN1
CN3
CN5
PE
CN2
CN1
CN2
G
T1
T2
3.3 Water Heater Installation
①
②
③
④
NOTE
The installation position of neutral line (blue), live line (brown/red) and earth line
(green/yellow) should be corresponding to the other end on wiring terminals.
Make sure the distance between the unit and surrounding wall is not less than 300mm, so
that to have enough space for maintenance purpose.
Determine the position of four fixing screws (attached with the unit), make four holes with
corresponding depth in the wall by means of a drill and drive a wall plug into the hole.
Drive in the screws on the top and ensure certain distance between screw head and wall
(See Fig.1)
Determine installation position of the unit according to length of power cord / position
of air switch (Distance between bottom and floor should be ≥1.6m).
Step 3 Step 4
Step 5 Step 6
Gash the middle of the film of the power cord
jacket with a sharp knife in order to put into
power lines.
Tighten the wire-pressing plate with screws to
primary position, ensure that the power cord not
be pulled out more than 60N.
Screw the power cord into the jacket for
installation of wire pressing plate.
Connect the power cord to wiring terminals; the
method is as shown in picture.
6
(Fig.2)
Water flow
adjusting
valve with
filter
Cold water inlet
Cold water inlet
3.4 Plumbing Connection
⑤
Mount the unit on the wall and tighten with two screws at bottom, connect the wires and
install top cover with the screws.
①
②
Shower flexible tube should be connected with water outlets and shower head separately,
attached sealing ring should be used at end face.
Water valve with filter should be installed at water inlet of the unit, sealing ring with filter
should be used at end face. (See Fig.2).
(Fig.1)
WARNING
Metallic / chromed hose and conductive control valve shall not be used.
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7
170
170
300
4.1 Operating Of The Unit
4.2 Leakage Testing
4.3 To Adjust Water Flow
Switch on the power supply, the unit will take self-inspection for 2s, “ELCB” green
indicator light will be on (under the condition of no electricity leakage). When the
water flow exceeds 1.2L/min, rotate the knob clockwise to switch on heating
power rotate switch, heating indicator light will be on, the unit start to work.
4. METHODS OF USING
When the water heater is working normally (including working state of PUMP),
press “TEST” button, if the leakage test circuit is no problem, “ELCB” green
indicator light will be off, and the unit will not heat. Press “RESET”, testing will
be canceled, and “ELCB” green indicator light will be on, the unit will be back
to working state set before. If the circuit leaks, press “RESET” button can’t
cancel leakagetesting, “EARTH”、“ELCB” and “POWER” indicator light is
twinkling flicker, it means the water heater has problems and can’t be used; all
the buttons are invalid, heating is stopped, and pump will be closed.
Rotate the handle of water flow adjusting valve to adjust the water flow.
4.4 Electricity Leakage Protection
When the electricity leakage testing circuit is working normally, if the leakage current is bigger
than certain value between 7.5mA and 15mA, “EARTH”、“ELCB” and “POWER” indicator light
will be twinkling flicker, no heating; it can only be used after the failure is excluded. (When
electricity leakage is tested, red and green indicator lights are all off, stop heating and close the
pump system.)
3.5 Power Supply Connection
3.6 Water Supply
①
②
③
Choose air switch with leakage protection according to power of water heater;
When connecting the water heater to electric network, please pay attention to connect live
line (red/brown), neutral line (blue) and earth line (yellow/green) with corresponding line in
electric network.
Adjust power selection knob to“OFF”;
NOTE
Water flow adjusting valve with filter must be used when install the unit. Blue marker
stands for water inlet, red marker stands for water outlet. Do not overexert to avoid
damaging the water heater.
NOTE
A private power cord should be used for this unit. After connecting to electric network,
please check the earth condition and make sure the earth resistance is <4Ω.
After all the plumbing is
finished
connecting, open water inlet valve of the product and supply
water to the unit to drain away air inside until there is stable water flow comes out from shower
head. Check whether there is leakage at joints or not. If there is, check whether the connecting
parts are fastened or not, then re-supply water.
8
This electric water heater should be installed at the place without sunshine or rain spray.
Please cut off power supply if not use for long time.
Please blow down the water for about 10 seconds to drain away the impurities in the pipe before
connecting the water source to the electric water heater to avoid blockage of water heater.
If long time no use the unit, check the water heater first before use. Electrify after the water
flows out stably.
Do not spray water to air switch or heater body directly, to avoid moist.
Please cut off the power in the weather of thunder and rain to avoid damaging the water heater.
If not use for long period of time, please cut off water inlet to prolong the lifespan of the water
heater.
Check the power cord connecting terminals frequently to make sure that they are well and
reliably contacted, no overheating phenomenon, and grounding is good or not.
Disassembly shower head and sealing ring with filter to clean periodically.
DECLARATION: this water heater can only be maintained by authorized service personnel,
incorrect installation and using method may cause serious injury or loss of property.
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5. MAINTENANCE
WARNING
Do cut off power supply before maintenance, to avoid danger like electric shock.
!
4.5 To Adjust Water Temperature
Rotate the handle of water flow adjusting valve to adjust to proper water flow. Adjust power by rotating
knob, clockwise rotate, power will be increased and water temperature increase accordingly or vice
versa.
NOTE
For first time using, ensure electrify after the unit is filled fully with water and there is
stable water flow comes out from shower head.
The electric water heater may be damaged if the water hardness is too high. To
guarantee the normal service life, please install and put it into use on condition that the
local water hardness is less than 450mg/L (CaCO3).
The water pressure is increased when Pump is started; Rotate Pump knob to adjust water pressure,
rotate clockwise, water pressure is increased and vice versa.
4.7 To Adjust Water Pressure (For MWH-38P3 & MWH-38P3-RS)
If the water flow is small and power is high while using the unit, outlet water temperature is rather
high; the unit will stop heating automatically. At this time, please lower the power and adjust the
water flow faster in order to avoid inconsistency of water temperature.
4.8 Use After Overheating Protection
9
When the unit is working under normal condition, press “PUMP”, The pump will start immediately and
has been working until the water flow insufficient 1.2L/min for more than 3 seconds.
4.6 To Activate Pump Function (For MWH-38P3 & MWH-38P3-RS)
10
SUGGESTIONS
1. Check whether power
is cut
2. Contact authorized
service personnel for
repair.
1. Rotate “TEMP” knob
2. Repair or replacement
the PCB
1. Press the reset handle
of the thermal cut out
after checking and
troubleshooting
2. Change the heating
elements
3. Adjustable water flow
4. Change the flow sensor
5. Open the flow sensor
and clean the rotor
1. Wait for restoration of
running water supply;
2. Open the inlet valve of
running water.
Adjust the heating power
lower, make the water
bigger.
Contact authorized service
personnel for repair.
Contact authorized service
personnel for repair.
REASONS
1. Power supply error;
2. PCB error;
1. The “TEMP” knob is off;
2.
3. The water flow
insufficient 1.2L/min;
PCB error;
4. Impurities clogging the
flow sensor of the rotor
1. The running water
supply is cut off;
2. The inlet valve of running
water is not open.
1. Water pressure is not
stable.
2. Outlet water temperature
is too high, overheating
protection again and
again.
Electricity leaks.
PUMP error.
Temperture sensor
is broken
Change the temperture
sensor
SYMPTOMS
The heating indicator light
is off and the outlet
water is cold.
The heating indicator light
is on and the outlet
water is cold.
6. TROUBLESHOOTING
Switch on the power
supply, ELCB indicator
light is off.
No water flows out from
the shower head.
Outlet water temperature
sometimes is hot,
sometimes is cold.
Pressure can’t be
increased.
1. The thermal cut out
is cut off
2. Heating elements
is broken
“EARTH”、“ELCB”and
“POWER” indicator light
is twinkling flicker at the
same time
“POWER” indicator light
is twinkling flicker
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