Daikin VRVIII-S, Service Manual

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Outline of Control (Indoor Unit) SiENBE34-703
64 Function
6.6 Electronic Expansion Valve Control
• Electronic expansion Valve Control
In cooling, to maximize the capacity of indoor unit heat exchanger (evaporator), operate the
electronic expansion valve under PI control so that the evaporator outlet superheated degree
(SH) will become constant.
In heating, to maximize the capacity of indoor unit heat exchanger (condenser), operate the
electronic expansion valve under PI control so that the evaporator outlet superheated degree
(Condenser outlet subcooled degree) will become constant.
Furthermore, the default value of the optimal evaporator outlet superheated degree (condenser
outlet subcooled degree) is 5 deg. However, this default value varies with the operating
performance.
6.7 Hot Start Control (In Heating Operation Only)
At startup with thermostat ON or after the completion of defrosting in heating operation, the
indoor unit fan is controlled to prevent cold air from blasting out and ensure startup capacity.
[Detail of operation]
When either the start condition 1 or the start condition 2 is established, the operations shown
below will be conducted.
Cooling SH=TH
2
-TH
1
SH : Evaporator outlet superheated degree
(Heating SC=TC-TH
1
) TH
1
: Temperature (°C) detected with the liquid thermistor
TH
2
: Temperature (°C) detected with the gas thermistor
SC : Condenser outlet subcooled degree
TC : High pressure equivalent saturated temperature
TH
2
: Temperature (°C) detected with the gas thermistor
TC : High pressure equivalent saturated temperature
Defrost ending or oil return ending
or Thermostat ON
The fan is not OFF before initiating the hot start: LL
The fan is OFF before initiating the hot start: OFF
Hot start control Hot start in progress
Normal control
Normal control
H/L remote
control setting
LL
OFF
Remote control
setting
Po (Horizontal)
Fa
n
Louv
er
Hot start ending conditions
·
lapse of 3 minutes
·
[TH2]>34°C
·
"Tc">52°C
OR