2WAY SYSTEM
Control Functions - Outdoor unit
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6. Outdoor Unit CCU (command controller
unit) Control
6. Outdoor Unit CCU (command controller unit) Control
2WAY VRF SYSTEM
Control Functions
*
Operating time “XX” under the section “(4) Drain Pump Control” described on previous page is able to set
in EEPROM of the main outdoor unit.
*
The drain pump always operates when the indoor unit is thermostat ON in cooling operation.
*
The above mentioned “XX” is able to set in EEPROM of the main outdoor unit.
∆To : Cooling (Discharge air temperature) - (Preset discharge air temperature)
Heating (Preset discharge air temperature) - (Discharge air temperature)
∆To ≤ - 3.5 degrees Celsius, and this condition continues for 7 minutes
∆To < - 2.0 degrees Celsius, and this condition continues for (20 + XX) minutes
*
In the above 2 cases, the drain pump operates by the signal of indoor PCB, not by the CCU.
Once the drain pump operates, it keeps operating for 20 minutes.
EEPROM setting in main outdoor unit
CODE: 2B
Setting No.
20
30
40
60
XX
20 (minutes)
30 (minutes)
(at factory shipment)
40 (minutes)
50
50 (minutes)
60 (minutes)
*
Regarding the preset discharge air temperature that is set in the indoor unit is able to change,
see the section “5. REMOTE CONTROLLER FUNCTIONS” in this Service Manual.
EEPROM setting in main outdoor unit
CODE: E1
Setting No.
-20
-19
-18
0
XX
-20 (minutes)
-19 (minutes)
...
...
-18 (minutes)
...
10
...
0 (minutes)
(at factory shipment)
10 (minutes)
(5) Discharge Air Temperature Control
For Type F2, M1 and E2 indoor units, discharge air temperature is controlled from the CCU to prevent
dew condensation on duct surface in cooling operation.
The CCU monitors and adjusts ∆To of indoor unit.
The adjustment is made by compressor capacity and MOV operation in the indoor unit.
Situation in which indoor unit thermostat OFF by discharge air temperature control
2WAY VRF SYSTEM
Control Functions
7. Oil Control
(1) Oil Level
(2) Oil Level Detection
Conditions of oil level in compressor
Judgment
Oil level
2
1
0
State
Sufficient
Possibility of
shortage
Shortage
The compressor contains sufficient oil.
There is no problem.
There will be a risk of oil shortage soon.
Confirm that oil is improved after performing
the oil recovery control operation.
The compressor oil is short against
required level for normal operation.
Confirm that oil level is improved after
performing the oil recovery control among
systems.
(4) Inter Outdoor Units Oil Recovery Control – Utilizing Balance Tubes
If the low oil level (1 or 0) continues, that outdoor unit (oil-receiving outdoor unit) receives oil from operating
outdoor units where the oil level is not low (oil-supply outdoor units whose all compressor oil levels are 2 or 1).
At the time immediately after the oil level changes from 2 to 1, there is a specified amount of oil in the compressor.
Namely, soon after the oil level is changed from 1 to 2, the oil in the compressor is sufficient.
After about 1-hour operation, if the oil level “0” indication continues for more than 5 to 10 minutes, it seems to come
short of oil in the system. Check valves related to oil recovery operation, the refrigerant tubing and for any oil leakage.
The compressor oil in the crankcase is sent by bypass via a capillary tube to the low-pressure circuit.
The temperature detected by an oil sensor is used to determine whether it is oil (warm) or refrigerant (cold).
(3) Self-separator Oil Recovery Control
When a low oil level (1 or 0) is detected, oil is recovered from the oil separator to the compressor through the ORVR.
Control at the oil-supply outdoor unit begins after an outdoor unit falls into low oil level state.
Oil supply is performed for a maximum of 5 minutes from each unit.
When oil supply is ended, oil supply from that outdoor unit will not occur again for a period of [(No. of outdoor
units minus 1) × 5 minutes]. In addition, oil supply is ended if the oil-receiving outdoor unit oil level changes to 2,
or if the oil-supply outdoor unit oil level becomes “0”.
The supply of oil is received from 1 unit at a time, in sequence, according to the order of priority of their inverter
compressors.
Solenoid valve control during unit compressor oil recovery
1. Oil-receiving outdoor unit
The ORVR turns ON and remains ON during compressor oil recovery.
2. Oil-supply outdoor unit
* The oil recovery might be performed regardless of oil level.
The BPV repeatedly turns ON and OFF according to a constant cycle.
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