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Controlling the Indoor Unit
< Indoor unit control >
Inside the indoor units 16 and 20 HP are two control boards to accommodate two-refrigerant circuits, and there is
one control board inside indoor unit 10HP to accommodate one-refrigerant circuits. Each refrigerant circuit is
controlled independently. See the following for various functions they perform.
[1] Thermostat Functions
(1) Functions of Thermostat and Selection of Function
· There are two control methods. One is to use suction temperature; the other is to use discharge temper-
ature.
· The switches on the address board inside indoor unit is used to switch between the above options.
· Factory setting: Discharge Temperature Control.
· When changing the setting, set the switches on both address boards inside the control to OPTION to
use suction temperature control. Set the switches to STANDARD to use discharge temperature control.
· Make sure that the settings on the two address boards inside 16 and 20P units match.
✻
Not applicable to 10HP
(2)
Thermostat Reading
1
Discharge Temperature Control (SWC is set to Standard)
(a) Thermo ON Condition
• Three minutes have past since thermo OFF AND
• TH24 - Target Temperature >1˚C AND
• TH21 is higher than when thermo is OFF.
TH24: Discharge thermistor
TH21: Suction thermistor
(b) Thermo OFF Condition
< When outdoor unit Dipsw3-7 are ON >
· 30 minutes have past since thermo ON AND
· TH24- Target Temperature < -1˚C has been detected for 10 minutes
OR TH24 - Target Temperature < 15˚C was detected
< When Outdoor unit Dipsw 3-7 are OFF>
· Two minutes have past since thermo ON
· TH24 - Target Temperature < -1˚C has been detected for 5 minute.
· When operating with the compressor running at its minimum capacity.
2
Suction Temperature Control (SWC is set to Option.)
(a) Thermo ON Condition
• Three minutes have past since thermo OFF AND
• TH21 - Target Temperature > 1˚C
(b) Thermo OFF Condition
< When outdoor unit Dipsw 3-7 are ON >
• Thirty minutes have past since thermo ON AND
• TH21 - Target Temperature < -1˚C has been detected for 10 minutes OR TH21 - Target
Temperature < -5˚C was detected.
< When outdoor unit Dipsw 3-7 are OFF >
• Two minutes have past since thermo ON AND
• TH21 - Target Temperature < -1˚C has been detected for 5 minute.
• When operating with the compressor running at its minimum capacity.
Address board
SWC
SWC
Option: Suction temperature control
Standard: Discharge temperature control
Control box
Address board
Control board
Remote controller