Electronic Expansion Valve Control; Circulation Airflow (Fxfsq-Ar Only) - Daikin VRV S RXQ4/5ARV1 Service Manual

Outline of Control (Indoor Unit)

3.10 Electronic Expansion Valve Control

Electronic expansion valves in indoor units have the functions of conducting superheating
degree control in cooling operation. However, if the indoor units receive any control command
such as a protection control command or a special control command from the outdoor unit, the
units will give a priority to the control command.
• Superheating degree control in cooling operation
This function is used to adjust the opening of the electronic expansion valve so that
superheating degree (SH), which is calculated from the detection temperature (Tg) of the gas
pipe thermistor (R3T) and the detection temperature (Tl) of the liquid temperature thermistor
(R2T) of the indoor unit, will come close to a target superheating degree (SHS).
At that time, correction to the superheating degree is made according to the differences (ΔT)
between set temperature and suction air temperature.
SH = Tg – Tl
where,
SH: Evaporator outlet superheating degree (°C)
Tg: Indoor unit gas pipe temperature (R3T)
Tl: Indoor unit liquid pipe temperature (R2T)
SHS (Target superheating degree)
• Normally 5°C.
• As ΔT (Remote controller set temp. – Suction air temp.) becomes larger, SHS becomes lower.
• As ΔT (Remote controller set temp. – Suction air temp.) becomes lower, SHS becomes larger.

3.11 Circulation Airflow (FXFSQ-AR only)

Unevenness of room temperature and the startup time are improved by repeating 2-direction
horizontal blow-off and swing alternately.
3.11.1 Initiation Conditions of Circulation Operation
When operation starts (in the startup state)
Circulation airflow operation is performed.
During normal operation
The unit automatically determines operation based on the room temperature condition and time
to switch circulation airflow operation and the normal auto airflow rate and direction (eco full
automatic control).
Circulation airflow
88
Circulation airflow operation continues for up to 90 minutes
Auto airflow rate and direction
Time
Circulation airflow
Set temp.
Target temp. Δt
Part 4 Functions and Control
SiAF332111E