Daikin VRV III RXYQ5-54PY1, Service Manual

Page: 124 / 398

Si34-601A Special Control
Function 113
3.4 Defrosting Operation
To defrost the outdoor unit heat exchanger while in Evaporator, the defrost operation is conducted to recover the
heating capacity.
[Start conditions]
Referring to the set conditions for the following items, start the defrosting operation.
• Heat transfer coefficient of the outdoor unit heat exchanger
• Heat exchange temperature (Tb)
• Timer (Set to two hours at minimum.)
Furthermore, the heat transfer coefficient of the outdoor unit Evaporator is computed from Tc, Te, and compressor
loads.
* In the case of multi-outdoor-unit system,
Master unit: Performs the operations listed in the table above.
Slave units: Operating units perform the operations listed in the table above.
Non-operating units perform the operations listed in the table above from the Defrost operation.
(Non-operating unit stops during “Defrost preparation operation”.)
*
Actuators are based on RXYQ14~18P.
Outdoor unit actuator
Defrost preparation
operation
Defrost operation Post Defrost operation
Compressor Upper limit control 176 Hz + ON + ON
124 Hz + OFF + OFF
2-steps increase/20sec.
till Pc - Pe>0.4 MPa
Outdoor unit fan
STEP7
or
STEP8
OFF STEP8
Four way valve ON OFF ON
Main motorized valve (EV1) SH control
→
480 pls 480 pls 55 pls
Subcooling motorized valve (EV2) 0 pls 0 pls 0 pls
Hot gas bypass valve (SVP) OFF OFF OFF
Accumulator oil return valve (SVO) ON ON ON
Injection (SVT) (RXYQ5P model only) OFF OFF OFF
Ending conditions 170 sec.
•
10 min.
•
Tb>11
°
C
•
10 sec.
•
Pc - Pe>0.4MPa
or
or
Indoor unit actuator During defrost
Fan
Thermostat ON unit OFF
Stopping unit OFF
Thermostat OFF unit OFF
Electronic expansion valve
Thermostat ON unit Defrost EV opening degree
Stopping unit 256 pls
Thermostat OFF unit Defrost EV opening degree