Refrigerant Drift Prevention - Daikin VRV-WIII RWEYQ72PTJU Service Manual

Special Operation
7.4

Refrigerant Drift Prevention

"Refrigerant drift prevention control" is carried out, in order to prevent refrigerant drift among
condensing units during heating operation using condensing multiple connection. Refrigerant
overcharged in condensing units are collected and transferred to other condensing units that are
refrigerant shortage by controlling the electronic expansion valve.
7.4.1 In case of cooling/heating changeover connection
When the evaporator outlet superheated degree is large, open the solenoid valve (Y4S) for venting
receiver refrigerant of the condensing units that are refrigerant shortage.
7.4.2 In case of cooling/heating simultaneous connection
When the evaporator outlet superheated degree is large, open the solenoid valve (Y4S) for venting
receiver gas of the condensing units that are refrigerant shortage and the solenoid valve (Y3S) for
pressurizing the receiver of the overcharged condensing units.
64
Normal operation
(Y4S = OFF)
Normal operation
(Y4S = OFF)
(Y3S = OFF)
When the evaporator outlet
superheated degree is large
When the evaporator outlet
superheated degree is small
When the evaporator outlet
superheated degree is large
When the evaporator outlet
superheated degree is small
SiUS30-1301
Y4S = ON
Y4S = ON
Y3S = ON
Function and Control