Mini VRF SYSTEM
Control Functions - Outdoor unit
1 - 24
1
8. Defrost Control
2WAY VRF SYSTEM
Control Functions
9. Defrost Control
(1) Type of Defrost Control
(2) Forced Conditions
This system uses the reverse cycle defrost.
Defrost does not begin again for 35 minutes of operation after defrost was once completed.
(3) Frost Detection
Frost detection does not occur for 5 minutes after operation starts.
Frost is detected when minimum heat exchanger temperature meets any one of the condition 1 - 3 below.
Condition 1: Minimum heat exchanger temperature drops below L2 line shown in the figure below and detects
twice for 4 minutes without interruption while the compressor is operating.
Condition 2:
-25
Minimum heat exchanger temperature °C
10
Ambient temperature°C
Frost detection area below the bold lines L1 and L2
L1
L2
15 (Defrosting operation-end temperature)
unit: °C
-1
-3
-8
-10
-25.5
-27.5
Minimum heat exchanger temperature drops below L1 line shown in the figure below and detects
for a total of 60 minutes while the compressor is operating.
Condition 3: Minimum heat exchanger temperature drops below -3°C and detects for a total of 90 minutes
while the compressor is operating.
Even if all indoor units are stopped while defrosting, defrost control continues until it ends.
If the outdoor unit is stopped while defrosting due to protection control or another reason, then defrost control will
not start for a minimum of 10 minutes after restart occurs.
2WAY VRF SYSTEM
Control Functions
(4)
When the heating operation time at system has exceeded “XX” minutes (35 minutes at initial setting), and at
least one unit satisfies the decision of defrosting, the defrosting operation is effective.
9. Defrost Control
Heating Operation Set Time (Defrosting Operation Prohibiting Time)
(5)
Defrost ends when either of the below defrost end judgment conditions is met.
Defrost End Judgment Conditions
(6)
If there is only 1 outdoor unit in the refrigerant system, a reverse cycle defrost will be carried out.
It is possible to change the stopped time according to the setting.
For the maximum defrost time, see the table shown above.
Reverse Cycle Defrost
* XX is able to set in EEPROM of main outdoor unit.
* Defrost control is also performed at outdoor units where the outdoor unit heat exchanger is not functioning as
an evaporator (such as stopped outdoor units).
EEPROM setting in main outdoor unit
CODE: A3
Setting No.
0
1
...
XX
0 (minutes)
35 (minutes)
(factory preset code)
1 (minutes)
...
35
...
60
...
60 (minutes)
Condition 1: The temperatures are 15°C or higher at all heat exchanger sensors installed on the outdoor
unit.
One minute has elapsed under the condition that the temperatures are 10°C or higher at all heat
exchanger sensors installed in the outdoor unit.
Condition 3:
Condition 2:
13 minutes have elapsed.
Defrost flow
E:
C:
Evaporator operation
Condenser operation
E → C:
C → E:
Switching evaporator operation to condenser operation
Switching condenser operation to evaporator operation
Indoor unit Cooling mode
Heating mode
Defrost
preparation
Defrost in
progress
Defrost
end
judgment
Defrost end
Thermostat ON
E
C→E
E → C
Thermostat OFF
E
C→E
E → C
Thermostat ON
E
C→E
E → C
Fan (only)
E
C→E
E → C
Thermostat OFF
E
C→E
E → C
Compressor
Operating
Operating
Stopped
4-way valve
OFF
ON→OFF
OFF→ON
Stopped
E
C→E
E → C
Outdoor unit status
C
E → C
C → E
Time
Maximum 15 minutes
40 seconds
1 minute
SM830258-01_欧州向け_1fan_mini_VRF.indb 24
18/03/06 9:09:51
Summary of Contents for S-22ML1E5
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