Daikin VRV IV-S RXTQ-TAVJU Series, Service Manual

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Basic Control SiUS331604E
35 Functions and Control
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Depending on the operating conditions of the compressor, the compressor can be run in an operating mode
different from the modes listed in the table above.
2.3 Electronic Expansion Valve PI Control
Main Electronic Expansion Valve Control
Carries out main electronic expansion valve PI control to maintain evaporator outlet superheated degree (SH) at
constant during heating operation thus making maximum use of the outdoor unit heat exchanger (evaporator).
The optimum initial value of the evaporator outlet superheated degree is 3°C (5.4°F), but varies depending on the
inverter compressor discharge pipe superheated degree.
Subcooling Electronic Expansion Valve Control
Carries out PI control of subcooling electronic expansion valve to keep the superheated degree (SH) of the outlet
gas pipe on the evaporator side for the full use of the subcooling heat exchanger.
RXTQ36TAVJU RXTQ48/60TAVJU
Step Frequency (Hz) Step Frequency (Hz)
1 48 1 45
2 52.5 2 52.5
3 57 3 57
4 61.5 4 61.5
5 67.5 5 66
6 75 6 72
7 81 7 78
8 90 8 85.5
9 100.5 9 96
10 105 10 105
11 111 11 108
12 114 12 112.5
13 118.5 13 115.5
14 129 14 121.5
15 141 15 128.1
16 153 16 145.5
17 163.5 17 154.5
18 174 18 163.5
19 181.5 19 178.5
20 192 20 196.5
21 201 21 216
22 211.5 22 223.5
23 222 23 232.5
24 228 24 244.5
25 243 25 253.5
26 253.5 26 255
27 265.5 27 273
28 277.5 28 288
29 289.5 29 309
30 301.5 30 327
SH = Ts1 – Te SH: Evaporator outlet superheated degree
Ts1: Suction pipe temperature detected by thermistor R3T
Te: Low pressure equivalent saturation temperature
SH = Tsh – Te SH: Evaporator outlet superheated degree
Tsh: Subcooling heat exchanger gas pipe temperature detected
with the thermistor R6T
Te: Low pressure equivalent saturation temperature