Heat Exchanger Capacity Control; Cooling Main / Heating Main; Heat Exchanger Capacity Shift Controlling; Operation Mode Selection And Controlling - Fujitsu Airstage VR-II Series Service Manual

2-5 HEAT EXCHANGER CAPACITY CONTROL

2-5-1 Operation mode selection and controlling

Under The heat exchanger capacity is controlled using the 4WV, fan, and EEV according to the target high and low pressures.
The method for changing the capacity of the heat exchanger differs depending on the operation mode.
System demand Heat-Ex conditions
Cooling
Heating
Cooling main
Heating main
2-5-2 Capacity control
The heat exchanger is operated at maximum efficiency by using each outdoor unit. (Max. 6 Heat exchanger can be used)
Slave1 r
Master r
HEX1
HEX1
HEX2
HEX2
(1) Cooling (In case of 3 outdoor units connection)
Heat Exchanger condition: Condensor
- 4WV ON / OFF (Dpending on HEX capacity shift)
Fan speed Controlling range
- 0 to 500 rpm Only one HEX in use
- 300 to 500 rpm During HEX capacity shift
- Over 500 rpm Full of Heat-Ex capacity

Heat Exchanger capacity shift controlling

- Increas: Upper HEX has a priority in usage condition.
(No available Upper HEX, Lower HEX use)
- Decrease: Lower HEX has a priority in stop condition.
Number of Condensor
Fan Speed
(rpm)
1 2
Target High pressure < Operating High Pressure
880
(920)
500
(500)
300 (300)
0
Target High pressure > Operating High Pressure
( ) :L-Chassis
(3) Cooling Main / Heating Main (In case of 3 outdoor units connection)
Heat Exchanger condition: Depending on the difference between operating pressure and the Target High pressure and the Target Low pressure.
Fan speed controlling: Depending on the condition of HEX (Condensor / Evaporator)
Heat Exchanger capacity shift controlling:
- Increas: Upper HEX has a priority in usage condition.
(No available Upper HEX, Lower HEX use)
- Decrease: Lower HEX has a priority in stop condition.
Number of Evaporator
Fan Speed
(rpm)
6 5
880 (920)
500 (500)
(300)
300
0
( ) :L-Chassis
Controling device
Condensor Fan Motor + 4WV (ON/OFF) +EEV
Evaporator Fan Motor (Max rpm) + 4WV (ON) +EEV
Condensor Fan Motor + 4WV (ON/OFF) + EEV
Evaporator Fan Motor + 4WV (ON) + EEV
Slave2 r
HEX1
HEX2
3 4 5 6
Heating Main
4 3 2 1 1
(2) Heating
Heat Exchanger condition: Evaporator
- 4WV ON state
Fan speed Controlling range
- Maximum speed
Heat Exchanger capacity shift controlling
- Use all of available HEXs (Maximum capacity)
Fan Speed
(rpm)
880 (920)
0
( ) :L-Chassis
Cooling Main
Number of Condensor
2 3 4 5 6
02 - 07
Control target
Target High pressure
Maximum control
Target High / Low pressure
Target High / Low pressure
Number of Evaporator
Maximum number of HEX available in use