Daikin VRV II RXYQ8MY1K, Service Manual

Page: 69 / 310

Basic Control Si39-502A
58 Function
2.3 Electronic Expansion Valve PI Control
Main Motorized Valve EV1 Control
Carries out the motorized valve (Y1E) PI control to maintain the evaporator outlet superheated
degree (SH) at constant during heating operation to make maximum use of the outdoor unit
heat exchanger (evaporator).
The optimum initial value of the evaporator outlet superheated degree is 5°C, but varies
depending on the discharge pipe superheated degree of inverter compressor.
Subcooling Motorized Valve EV2 Control
Makes PI control of the motorized valve (Y2E) to keep the superheated degree of the outlet gas
pipe on the evaporator side for the full use of the subcooling heat exchanger.
2.4 Step Control of Outdoor Unit Fans
Used to control the revolutions of outdoor unit fans in the steps listed in table below, according to condition changes.
∗
Figures listed above are all those controlled while in standard mode, which vary when the system is set to high static
pressure or capacity precedence mode.
SH = Ts - Te SH : Evaporator outlet superheated degree (°C)
Ts : Suction pipe temperature detected by
thermistor R2T (°C)
Te : Low pressure equivalent saturation
temperature (°C)
SH = Tsh -Te SH : Outlet superheated degree of evaporator (
°
C)
Tsh : Suction pipe temperature detected with the
thermistor R5T (
°
C)
Te : Low pressure equivalent saturation
temperature (
°
C)
STEP
No.
Fan revolutions (rpm)
RXYQ8M RXYQ10M
0 0 0
1 300 300
2 320 320
3 345 345
4 385 385
5 465 465
6 575 575
7 765 785
8 825 825