Wellea Monobloc
23
P
art
3
- Con
tr
ol
6
Special Control
6.1
Oil Return Operation
In order to prevent the compressor from running out of oil, the oil return operation is conducted to recover oil that has
flowed out of the compressor and into the refrigerant piping. When the oil return operation is being conducted, the
outdoor unit refrigerant system main PCB displays code d0.
Timing of oil return operation:
When the compressor cumulative operating time with running rotation speed less than 42rps reaches 6 hours.
The oil return operation ceases when any one of the following three conditions occurs:
Oil return operation duration reaches 5 minutes.
Compressor stops.
Mode change command is received.
Tables 3-7.1 show component control during oil return operation in cooling mode.
Table 3-7.1: Outdoor unit component control during oil return operation in cooling mode
Component
Wiring diagram
label
5/7/9kW
12/14/16
kW
Control functions and states
Inverter compressor
COMP
●
●
Runs at oil return operation rotation speed
DC fan motor / Upper DC fan motor
FAN1 / FAN_UP
●
●
Controlled according to outdoor heat exchanger pipe
temperature
Lower DC fan motor
FAN_DOWN
●
Electronic expansion valve
EXV
●
●
304 (steps)
Four-way valve
ST
●
●
Off
Tables 3-7.2 show component control during oil return operation in heating and DHW modes.
Table 3-7.2: Outdoor unit component control during oil return operation in heating and DHW modes
Component
Wiring diagram
label
5/7/9kW
12/14/16
kW
Control functions and states
Inverter compressor
COMP
●
●
Runs at oil return operation rotation speed
DC fan motor / Upper DC fan motor
FAN1 / FAN_UP
●
●
Controlled according to outdoor heat exchanger pipe
temperature
Lower DC fan motor
FAN_DOWN
●
Electronic expansion valve
EXV
●
●
304 (steps)
Four-way valve
ST
●
●
On
6.2
Defrosting Operation
In order to recover heating capacity, the defrosting operation is conducted when the outdoor unit air side heat exchanger
is performing as a condenser. The defrosting operation is controlled according to outdoor ambient temperature, air side
heat exchanger refrigerant outlet temperature and the compressor running time.
The defrosting operation ceases when any one of the following three conditions occurs:
Defrosting operation duration reaches 10 minutes.
The air side heat exchanger refrigerant outlet temperature is above 8°C for more than 10 seconds.
The air side heat exchanger refrigerant outlet temperature is above 12°C.
