Midea M thermal Mono Series User manual

M thermal Mono Series
Commercial Air Conditioners
R32
Service
Manual
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M thermal Mono
2020041
CONTENTS
CONTENTS
Part 1 General Information............................................................................ 3
Part 2 Component Layout and Refrigerant Circuits ..................................... 5
Part 3 Control ............................................................................................... 15
Part 4 Diagnosis and Troubleshooting......................................................... 31
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CONTENTS
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Part 1 - General Information
Part 1
General Information
1 Unit Capacities and External Appearance.............................................. 4
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1Unit Capacities and External Appearance
1.1 Unit Capacities
Table 1-1.1: Capacity range
Capacity
4kW
6kW
8kW
10kW
12kW
14kW
16kW
Model1
(MHC-*/D2N82)
V4W
V6W
V8W
V10W
V12W
V14W
V16W
Capacity
12kW
14kW
16kW
Model1
(MHC-*/D2RN82)
V12W
V14W
V16W
Notes:
1. The full model names can be obtained by substituting the asterisk in the model name format given in the left-hand column of the table above
with the shortened model names given in the table. For example, the model name for the 8kW model is MHC-V8W/D2N8.
2. The presence or omission of the letter R in the model names indicates the unit’s power supply:
R: 3-phase, 380-415V, 50Hz; Omitted: 1-phase, 220-240V, 50Hz.
1.2 External Appearance
Table 1-1.2: Unit appearance
4/6kW
8/10/12/14/16kW
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Part 2 - Component Layout and Refrigerant Circuits
Part 2
Component Layout and
Refrigerant Circuits
1 Layout of Functional Components.............................................................. 6
2 Piping Diagrams ....................................................................................... 11
3 Refrigerant Flow Diagrams....................................................................... 13
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1Layout of Functional Components
MHC-V4W/D2N8-B / MHC-V6W/D2N8-B
Figure 2-1.1: MHC-V4(6)W/D2N8-B top view
Figure 2-1.2: MHC-V4(6)W/D2N8-B front view
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Part 2 - Component Layout and Refrigerant Circuits
Figure 2-1.3: MHC-V4(6)W/D2N8-B
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MHC-V8W/D2N8-B / MHC-V10W/D2N8-B
Figure 2-1.1: MHC-V8(10)W/D2N8-B top view
Figure 2-1.2: MHC-V8(10)W/D2N8-B front view
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Part 2 - Component Layout and Refrigerant Circuits
MHC-V12W/D2N8-B / MHC-V14W/D2N8-B / MHC-V16W/D2N8-B
Figure 2-1.4: MHC-V12(14, 16)W/D2N8-B top view
Figure 2-1.5: MHC-V12( 14, 16)W/D2N8-B, MHC-V12(14, 16)W/D2RN8-B front view
MHC-V12W/D2RN8-B / MHC-V14W/D2RN8-B / MHC-V16W/D2RN8-B
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Figure 2-1.4: MHC-V12(14, 16)W/D2RN8-B top view
Figure 2-1.5: MHC-V12( 14, 16)W/D2N8-B, MHC-V12(14, 16)W/D2RN8-B front view
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Part 2 - Component Layout and Refrigerant Circuits
2Piping Diagrams
Figure 2-2.1: MHC-V4 (6) W/D2N8-B / MHC-V12( 14, 16) W/D2N8-B / MHC-V12 (14, 16) W/D2RN8-B piping diagram
Figure 2-2.2: MHC-V8(10) W/D2N8-B / MHC-V12( 14, 16) W/D2N8-B / MHC-V12 (14, 16) W/D2RN8-B piping diagram
d
e
s
c
Compressor Accumulator
Condenser
EXV
Evaporator
Twin
Twout
T2
T2b F
Pressure sensor
Safety valve Air purge valve Pump
Flow switch
High-pressure switch
Expansion vessel
Manometer
Single way solenoid valve Capillary
Discharge temp. sensor
DC motor
T4
T3
Filter
Suction temp. sensor
Filter
Low-pressure switch
F
d
e
s
c
Compressor Accumulator
Condenser
EXV
Evaporator
Twin
Twout
T2
T2b
Pressure sensor
Safety valve Air purge valve Pump
Flow switch
High-pressure switch
Expansion vessel
Manometer
Single way solenoid valve Capillary
Discharge temp. sensor
DC motor
T4
T3
Filter
Suction temp. sensor
Filter
Low-pressure switch
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Key components:
1. Accumulator:
Stores liquid refrigerant and oil to protect compressor from liquid hammering.
2. Electronic expansion valve (EXV):
Controls refrigerant flow and reduces refrigerant pressure.
3. Four-way valve:
Controls refrigerant flow direction. Closed in cooling mode and open in heating mode. When closed, the air side heat
exchanger functions as a condenser and water side heat exchanger functions as an evaporator; when open, the air
side heat exchanger functions as an evaporator and water side heat exchanger function as a condenser.
4. High and low pressure switches:
Regulate refrigerant system pressure. When refrigerant system pressure rises above the upper limit or falls below the
lower limit, the high or low pressure switches turn off, stopping the compressor.
5. Air purge valve:
Automatically removes air from the water circuit.
6. Safety valve:
Prevents excessive water pressure by opening at 43.5 psi (3 bar) and discharging water from the water circuit.
7. Expansion vessel:
Balances water system pressure. (Expansion vessel volume: 8L)
8. Water flow switch:
Detects water flow rate to protect compressor and water pump in the event of insufficient water flow.
9. Backup heater:
Provides additional heating capacity when the heating capacity of the heat pump is insufficient due to very low
outdoor temperature. Also protects the external water piping from freezing.
10. Water pump:
Circulates water in the water circuit.
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Part 2 - Component Layout and Refrigerant Circuits
3Refrigerant Flow Diagrams
Heating and domestic hot water operation(4,6KW for example)
Figure 2-3.1: Refrigerant flow during heating or domestic hot water operation
Cooling and defrosting operation(4,6KW for example)
Figure 2-3.2: Refrigerant flow during cooling and defrosting operations
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Part 3 - Control
Part 3
Control
1 Stop Operation ........................................................................................ 16
2 Standby Control ....................................................................................... 16
3 Startup Control ........................................................................................ 17
4 Normal Operation Control ....................................................................... 19
5 Protection Control ................................................................................... 21
6 Special Control......................................................................................... 25
7 Role of Temperature Sensors in Control Functions ................................... 28
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1Stop Operation
The stop operation occurs for one of the following reasons:
1. Abnormal shutdown: in order to protect the compressors, if an abnormal state occurs the system makes a 'stop with
thermo off’ operation and an error code is displayed on the outdoor unit PCB digital displays and on the user
interface.
2. The system stops when the set temperature has been reached.
2Standby Control
2.1 Crankcase Heater Control
The crankcase heater is used to prevent refrigerant from mixing with compressor oil when the compressors are stopped.
The crankcase heater is controlled according to outdoor ambient temperature and the compressor on/off state. When the
outdoor ambient temperature is above 8°C or the compressor is running, the crankcase heater is off; when the outdoor
ambient temperature is at or below 8°C and either the compressor has been stopped for more than 3 hours or the unit has
just been powered-on (either manually or when the power has returned following a power outage), the crankcase heater
turns on.
2.2 Water Pump Control
When the outdoor unit is in standby, the internal and external circulator pumps run continuously.
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Part 3 - Control
3Startup Control
3.1 Compressor Startup Delay Control
In initial startup control and in restart control (except in oil return operation and defrosting operation), compressor startup
is delayed such that a minimum of the set re-start delay time has elapsed since the compressor stopped, in order to
prevent frequent compressor on/off and to equalize the pressure within the refrigerant system. The compressor re-start
delays for cooling and heating modes are set on the user interface. Refer to the M thermal Mono Engineering Data Book
Part 3, 7.5 “COOL MODE SETTING Menu” and Part 3, 7.6 “HEAT MODE SETTING Menu”.
3.2 Compressor Startup Program
In initial startup control and in re-start control, compressor startup is controlled according to outdoor ambient
temperature. Compressor startup follows one of two startup programs until the target rotation speed is reached. Refer to
Figures 3-3.1, 3-3.2, 3-3.3 and 3-3.4.
Figure 3-3.1: 4-6kW to 12-16kW Compressor startup program1,2 when ambient temperature is above 3°C
10
20
30
40
50
60
70
80
90
38Hz
40S 32Hz
60S
42Hz
40S
56Hz
40S
66Hz
40S
70Hz
120S
82Hz
120S
目标频率
时间
Hz
Figure 3-3.2: 8-10kW Compressor startup program1,2 when ambient temperature is above 11°C
42Hz
90S36Hz
60S
42Hz
40S
56Hz
40S
66Hz
40S
70Hz
40S
82Hz
120S
目标频率
时间
Hz
TIME
TARGET FREQUENCY
TIME
TARGET FREQUENCY
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Figure 3-3.3: 4-10KW compressor startup program1 when ambient temperature is at or below
3°C(4-6KW)/11°C(8-10KW)
Figure 3-3.4: 12-16KW compressor startup program1 when ambient temperature is at or below 3°C
Notes:
1. Once the first, 40-second stage of the program is complete, the program proceeds to the subsequent stages in a
step-by-step fashion and exits when the target rotation speed has been reached.
3.3 Startup Control for Heating and Domestic Hot Water Operation
Table 3-3.1: Component control during startup in heating and domestic hot water modes
Component
Wiring diagram
label
4/6kW
8/10/12/
14/16kW
Control functions and states
Inverter compressor
COMP
●
●
Compressor startup program selected according to
ambient temperature1
DC fan motor
FAN
●
●
Fan runs at maximum speed2
Electronic expansion valve
EXV
●
●
Position (steps) from 0 (fully closed) to 480 (fully
open), controlled according to outdoor ambient
temperature, discharge temperature and suction
superheat
Four-way valve
ST
●
●
On
3.4 Startup Control for Cooling Operation
Table 3-3.2: Component control during startup in cooling mode
Component
Wiring diagram
label
4/6kW
8/10/12/
14/16kW
Control functions and states
Inverter compressor
COMP
●
●
Compressor startup program selected according to
ambient temperature1
DC fan motor
FAN
●
●
Fan run at maximum speed2
Electronic expansion valve
EXV
●
●
Position (steps) from 0 (fully closed) to 480 (fully
open), controlled according to outdoor ambient
temperature, discharge temperature and suction
superheat
Four-way valve
ST
●
●
Off
Notes:
1. Refer to Figure 3-3.1, Figure 3-3.2, Figure 3-3.3 and Figure 3-3.4 in Part 3, 4.2 “Compressor Startup Program”.
2. Refer to Table 3-4.3 in Part 3, 5.6 “Outdoor Fan Control”.
TARGET FREQUENCY
TIME
TARGET FREQUENCY
TIME
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