[ VII Control ]
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HWE1018A GB
-8- Refrigerant Recovery Control
Recovery of refrigerant is performed during heating operation to prevent the refrigerant from accumulating inside the unit while
it is stopped (unit in fan mode), or inside the indoor unit that is in cooling mode or in heating mode with thermo off. It is also
performed during cooling operation to prevent an excessive amount of refrigerant from accumulating in the outdoor heat ex-
changer.
It is also performed during cooling operation to prevent an excessive amount of refrigerant from accumulating in the outdoor
heat exchanger.
(1) During heating operation
Starting refrigerant recovery mode
The refrigerant recovery mode in heating starts when all of the following three conditions are met:
15 minutes have passed since the completion of previous refrigerant recovery.
TH4 > 115°C [239°F]
Frequencies below 50 Hz
Refrigerant recovery
1) Refrigerant is recovered with the LEV on the applicable indoor unit (unit under stopping mode, fan mode, cooling, heating with
thermo off) being opened for 30 seconds.
2) Periodic capacity control of the outdoor units and periodic LEV control of the indoor units will be suspended during refrigerant
recovery operation; they will be performed after the recovery has been completed.
(2) During cooling operation
Starting refrigerant recovery mode
The refrigerant recovery mode starts when all the following conditions are met:
30 minutes have passed since the completion of previous refrigerant recovery.
When the unit keeps running for 3 minutes in a row or more with high discharge temperature
TH4 > 105°C [221°F] or 63HS1 > 3.43 MPa [497 psi] (35 kg/cm
2
G) and SC0 > 10°C [18°F]
Refrigerant recovery
The opening of LEV1 is increased and periodic control begins again.
-9- Capacity Control of Outdoor Fan
(1) Control method
Depending on the capacity required, the rotation speed of the outdoor unit fan is controlled by the inverter to keep a constant
condensing temperature during cooling operation and a constant evaporation temperature during heating operation.
(2) Control
Outdoor unit fan stops while the compressor is stopped (except in the presence of input from snow sensor).
The fan operates at full speed for 5 seconds after start-up.(Only when TH7<0°C [32°F])
The outdoor unit fan stops during defrost operation.
-10- Subcool Coil Control (Linear Expansion Valve <LEV1>)
The OC and OS control the subcool coil individually.
The LEV is controlled every 30 seconds to maintain constant the subcool at the outdoor unit heat exchanger outlet that is
calculated from the values of high pressure (63HS1) and liquid piping temperature (TH3), or the superheat that is calculated
from the values of low pressure (63LS) and the bypass outlet temperature (TH2) of the subcool coil.
LEV opening is controlled based on the values of the inlet (TH6) and the outlet (TH3) temperatures of the subcool coil, high
pressure (63HS1), and discharge temperature (TH4). The LEV is closed (0) in the heating mode, while the compressor is
stopped, and during cooling Thermo-OFF. The LEV opens to a specified position when 15 minutes have passed after Thermo-
OFF. (65 pulses)
During defrost, normally, the valve is initially set at 0 pulse, although it may operate at higher pulses depending on the 63 LS
and TH4 status.
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