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HWE09080 GB
-11- Subcool Coil Control (Linear Expansion Valve <LEV1>) <PQHY only>
The OC, OS1, and OS2 controls the subcool coil individually.
The LEV is controlled every 30 seconds to maintain constant the subcool at the heat source 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). In a single-heat source-unit system, the LEV is closed (0) in the heating
mode, while the compressor is stopped, and during cooling Thermo-OFF. In a multiple-heat source-unit system, the LEV clos-
es (0) during heating operation, while the compressor is stopped, or during cooling Thermo-OFF. The LEV opens to a speci-
fied position when 15 minutes have passed after Thermo-OFF. (65 pulses)
LEV1 outputs 0 pulse during the defrost cycle, and 300 pulses if either of the following formulas are satisfied: 63LS<2kgf/cm
2
or TH4100ºC [212ºF].
-12- Refrigerant flow control (Linear expansion valve <LEV2a, LEV2b>)<PQHY only>
Refrigerant flow is controlled by each unit in the combined models during heating. Refrigerant flow control is performed by the
OC, OS1, and OS2 individually. The valve opens to a specified angle during cooling (Opening: 1400 pulses)
Valve opening is controlled based on the values of high pressure (63HS1), discharge temperature (TH4), low pressure(
63LS), and piping temperature (TH5).
The valve moves to the predetermined position while the unit is stopped.
-13- Control at Initial Start-up
When started up for the first time before 12 hours have elapsed after power on, the unit goes into the initial startup mode.
At the completion of the initial operation mode on the OC, OS1, and OS2, they will go into the normal control mode.
1. Flowchart of initial operation
(1) P72, P96, P120 models
50 F 60Hz
or F < 50Hz
Initial startup mode starts.
Completed in the integrated operation time of 35 minutes.
Initial startup mode complete
Completed in the integrated operation time of 90 minutes.