Daikin VRV III RXYQ5-54PY1 Service Manual page 151

Outline of Control (Indoor Unit)
(2) Heating operations
Discharge
air
T4
EV
T1: Temperature detected by suction air thermistor Th1
T2: Temperature detected by liquid pipe temp. thermistor Th2
T3: Temperature detected by gas pipe temp. thermistor Th3
T4: Temperature detected by discharge air thermistor Th4
Tc : Outdoor unit condensing temperature
EV: Electronic expansion valve opening
If the discharge temperature
T4 is lower than the discharge
setting temperature Ts
No
Judge if the superheat degree
is not too small when the EV is
opened.
EV=EV+∆EV
140
T2
Yes
Is EV possible
to open?
Yes
If yes,
EV is opened
CPU
T1
SC=Tc–T2
T4 < Ts?
EV possible to
If yes,
EV is closed.
EV=EV–∆EV
Refrigerant
Tc
(From Outdoor unit)
Ts
Temp.
Setting
Refrigerant
Calculate superheat degree.
If the discharge temperature T4
is higher than the discharge
setting temperature Ts
No
Is
close?
Judge if the superheat degree
Yes
is not too large when the EV is
closed.
Si34-601A
No
Function