Midea MWH-38Q User Manual
Instant Electric Water Heater
Instruction Manual
For Model: MWH-38Q
The diagram above is just for reference. Please take the
appearance of the actual product as the standard.
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.
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.
TABLE OF CONTENTS
TITLE PAGE
1.Cautions ...........................................................................................................................(2)
2.Product introduction .........................................................................................................(3)
3.Unit installation .................................................................................................................(5)
4.Methods of using ..............................................................................................................(8)
5.Maintenance.....................................................................................................................(9)
6.Troubleshooting.............................................................................................................. (10)
1
1. CAUTIONS
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.
Special Cautions
●
This water heater is for household, and it can be installed wherever place that need hot water,
eg. Washing hands, dishes or foods, and so on. (Multi directional water supply is not available).
●
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 water heater should be installed indoor，where temperature keeps over 0℃. If the water
inside of water heater has been frozen, it’s forbidden to turn on water heater before the ice
meltdown.
●
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.
●
The shower head must be descaled regularly.
●
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.
●
For any improper installation and incorrect operation of this product, our company will not be
liable for any responsibility.
2
!
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.
2. PRODUCT INTRODUCTION
2.1 Technical Performance Parameters
WARNING
MWH-38QModel
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
240V~
50Hz
3800W
16A
2.0mm²
≥20A
0 MPa
2 Liters/minute
0.02 MPa
0.3 MPa
I
IP25
224×330×93 mm
1
3
2.2 Parts Identification
Thermal
cut out
Heating
elements
assembly
Stainless
steel circlip
Temperature
sensor
Terminal block
Wire pressing board
Main control board
Indicator light board
Silicon control
Flow sensor
2.3 Internal Wire Diagram
Temperature Sensor
Thermal
Red
Cut Out
L
N
E
Blue
Yellow/Green
Terminal Block
Marker for
wateroutlet
Red Blue
Key board
Water outlet
Indicator Light Board
Key Board
CN1
CN2
ELCB
CN3
Main Control Board
CN5
CN4
Relay
Relay
Flow Sensor
CN6
Heating Elements
Marker for
water inlet
Water inlet
Temperature
Adjusting
Board
Silicon Control
WIRING DIAGRAM
T1
T2
G
E
4
3. UNIT INSTALLATION
3.1 Installation Instruction
Check the capacity of power circuit;
①
Power cord installation;
②
③
Water heater installation;
④
Plumbing connection;
⑤
Power supply connection;
Water Supply.
⑥
3.2 Power Cord Installation
Step 1 Step 2
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.
Step 3 Step 4
Gash the middle of the film of the power cord
jacket with a sharp knife in order to put into
power lines.
Screw the power cord into the jacket for
installation of wire pressing plate.
Step 5 Step 6
Tighten the wire-pressing plate with screws to
primary position, ensure that the power cord not
be pulled out more than 60N.
Connect the power cord to wiring terminals; the
method is as shown in picture.
5
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.
3.3 Water Heater Installation
Determine installation position of the unit according to length of power cord / position
①
of air switch (Distance between bottom and floor should be ≥1.6m).
Make sure the distance between the unit and surrounding wall is not less than 300mm, so
②
that to have enough space for maintenance purpose.
Determine the position of four fixing screws (attached with the unit), make four holes with
③
corresponding depth in the wall by means of a drill and drive a wall plug into the hole.
④
Drive in the screws on the top and ensure certain distance between screw head and wall
(See Fig.1)
⑤
Mount the unit on the wall and tighten with two screws at bottom, connect the wires and
install top cover with the screws.
120
250
180
3.4 Plumbing Connection
Water valve with filter should be installed at water inlet of the unit, sealing ring with filter
①
should be used at end face. (See Fig.2).
Shower flexible tube should be connected with water outlets and shower head separately,
②
attached sealing ring should be used at end face.
!
Metallic / chromed hose and conductive control valve shall not be used.
WARNING
6
(Fig.1)
Water flow adjusting
valve with filter
Cold water inlet
(Fig.2)
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.
3.5 Power Supply Connection
Adjust power selection knob to“OFF”;
①
Choose air switch with leakage protection according to power of water heater;
②
When connecting the water heater to electric network, please pay attention to connect live
③
line (red/brown), neutral line (blue) and earth line (yellow/green) with corresponding line in
electric network.
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.
3.6 Water Supply
After all the plumbing is
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.
finished
connecting, open water inlet valve of the product and supply
7
4. METHODS OF USING
4.1 Operating Of The Unit
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.
4.2 Leakage Testing
ELCB
POWER
LOW
When the water heater is working normally, 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, “ELCB” and
“POWER” indicator light is twinkling flicker, it means the water heater has
MAXOFF
TEST
RESET
problems and can’t be used; all the buttons are invalid, heating is stopped, and
pump will be closed.
4.3 To Adjust Water Flow
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, the POWER red and ELCB green indicator light will be
off, no heating; it can only be used after the failure is excluded. (When electricity leakage is tested,
“ELCB” and “POWER” indicator light will be twinkling flicker, stop heating )
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.
4.6 Use After Overheating Protection
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.
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).
8
5. MAINTENANCE
●
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.
!
Do cut off power supply before maintenance, to avoid danger like electric shock.
WARNING
9
6. TROUBLESHOOTING
SYMPTOMS
Switch on the power
supply, ELCB indicator
light is off.
The heating indicator light
is off and the outlet
water is cold.
The heating indicator light
is on and the outlet
water is cold.
No water flows out from
the shower head.
Outlet water temperature
sometimes is hot,
sometimes is cold.
REASONS
1. Power supply error;
2. PCB error;
3. Thermal cut out acts.
1. The “TEMP” knob is off;
2.
PCB error;
3. The water flow
insufficient 1.2L/min;
4. Impurities clogging the
flow sensor of the rotor.
1. The Silicon control is
cut off.
2. Heating elements
is broken.
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.
SUGGESTIONS
1. Check whether power
is cut.
2. Contact authorized
service personnel for
repair.
1. Rotate “TEMP” knob
2. Repair or replacement
the PCB.
3. Adjustable water flow.
4. Change the flow sensor.
5. Open the flow sensor
and clean the rotor.
1. Press the reset handle
of the Silicon control
after checking and
troubleshooting.
2. Change the heating
elements.
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.
“ELCB”and“POWER”
indicator light is twinkling
flicker at the same time
“POWER” indicator light
is twinkling flicker
Electricity leaks.
Temperture sensor
is broken.
10
Contact authorized service
personnel for repair.
Change the temperture
sensor.
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