Si30-408 Points of Refrigerant Control of VRV System
Basic Information 27
3.4 Control of Electronic Expansion Valve
Electronic
Expansion Valve
of Outdoor Unit
In Cooling Operation
In cooling operation, outdoor electronic expansion valve should basically be fully open.
Note: In some models of type L or newer, the valve can be fully closed with a bridge circuit.
In Heating Operation = Superheated Degree Control
Superheated degree [SH] is calculated from the low pressure equivalent saturation temperature
(Te) converted from the pressure detected by the low pressure sensor of outdoor unit (Pe) and
temperature detected by suction pipe thermistor (Te). Electronic expansion valve opening
degree is so regulated that the superheated degree [SH] becomes close to targeted
superheated degree [SHS].
When SH > SHS, adjust to make opening degree wider than present one.
When SH < SHS, adjust to make opening degree narrower than present one.
SH : Superheated degree (Ts – Te)
SHS : Target superheated degree (Normally 5°C)
Electronic
Expansion Valve
of Indoor Unit
In Cooling Operation = Superheated Degree Control
Superheated degree [SH] is calculated from temperature detected by the gas pipe thermistor of
indoor machine (Tg) and the temperature detected by liquid pipe thermistor (Tl). Electronic
expansion valve opening degree is so controlled that the superheated degree [SH] becomes
close to targeted superheated degree [SHS].
The compensation is made based on the temperature difference between setting temperature
and suction air thermistor temperature (∆T).
When SH > SHS, adjust to make opening degree wider than the present one.
When SH < SHS, adjust to make opening degree narrower than the present one.
SH : Superheated degree (Tg – Tl)
SHS : Target superheated degree
[Normally 5°C, however, when the temperature difference (∆T) decreases, SHS
increases. (even when SH is large, the opening degree becomes small.)]
∆T : Remote controller setting temperature - suction air thermistor detection value
Subcooled Degree Control in Heating Operation
Subcooled degree [SC] is calculated from the high pressure equivalent saturation temperature
(Tc) converted from the pressure detected by high pressure sensor of outdoor unit and the
temperature detected by liquid pipe thermistor of indoor unit (Tl). Electronic expansion valve
opening degree is so regulated that the subcooled degree [SC] is close to target subcooled
degree [SCS].
The compensation is made based on the temperature difference between setting temperature
and suction air thermistor temperature (∆T).
When SC > SCS, adjust so to make opening degree wider than present one.
When SC < SCS, adjust so to make opening degree narrower than present one.
SC : Superheated degree (Tc – Tl)
SCS : Target subcooled degree.
[Normally 5°C, however, when the temperature difference (∆T) decreases, SCS
increases. (even when SC is large, the opening degree becomes small.)]
∆T : Remote controller setting temperature - suction air thermistor detection value
(Reference) Control range of outdoor electronic expansion valve
• R22 unit ... 0 to 2000pls
• R407C unit ...
Ve-up standard (RSXYP 5 to 10L): 0 to 480 pls
Others: 0 to 2000 pls
• R410 A unit ... 0 to 1400 pls
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