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Mini VRF SYSTEM
Control Functions
Example:
2-3-1. Roadmap control in cooling mode
With this control, the below evaporation temperature control and condensation temperature control are both used.
Control is performed according to the following order of priority:
Control order of priority Area C > Area B > Area A
When Evaporation temperature control = Area A, and Condensation temperature control = Area C,
then based on the above order or priority, the result is “Area C = Reduce horsepower.”
Horsepower increase prohibited
Horsepower increase permitted
Horsepower decrease
(Area A)
(Area B)
(Area C)
5.1°C
5.0°C
2.0°C
1.9°C
(1)
(2)
(3)
(4)
(5)
(6)
Fig. 1-1
For indoor units that are operating in Cooling mode, if one unit is selected for a test run, then the air intake
temperature difference (difference between the room temperature setting and indoor unit air intake tempera-
ture) is ignored, and areas B and C are considered to be area A for control purposes. (This is used for addi-
tional refrigerant charging, test run checks, etc.)
For this reason, vapor may be discharged if the test run continues for a long period of time, however this does
not indicate a problem.In addition, the test run is canceled automatically after 1 hour.
Even within the same area, the compressor capacity varies depending on the refrigerant temperature.
For 6 minutes after the compressors start, area C is considered to be area B for control purposes.
During special control, control of the compressor capacity according to Te is not performed.
If the thermostat turns OFF while Te is within area C, the next time the compressor starts it may restart from a
lower capacity.
When the area changes to area C, area C is considered to be area B for control purposes for the first 6 min-
utes, even if the horsepower is the minimum value within the range where capacity control is possible (opera-
tion with inverter frequency of 25 Hz only). Subsequently if C area continues, the thermostat turns OFF.
Horsepower increase prohibited
(Area C)
(Area D)
Horsepower decrease
Horsepower increase permitted
Thermostat OFF
(Area A)
(Area B)
53.5°C
53.4°C
54.6°C
54.5°C
57.5°C
57.4°C
Evaporation temperature (=Te) control
Condensation temperature (=Tc) control
Fig. 1-2
2. Compressor Control
SM830195-04_Mini VRF SYS.indb 4 15/03/10 17:47:32
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