Daikin VRV II REYQ10MY1B, Service Manual

Page: 84 / 309

Si39-306 Special Control
Function 73
3.3 Defrosting Operation
In order to melt the frost accumulated on the heat exchanger during heating operation,
Defrost operation is performed to restore the heating capacity.
[Starting conditions]
Start defrosting operation referring to the following conditions.
* Heat conductivity of outdoor heat exchangers
* Heat exchange temperature (Tb)
* Timer (Min. 2 hours)
The heat conductivity of outdoor heat exchangers is calculated based on To, Te, and
compressor load.
* 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 units stops during “Defrost preparation operation”)
* Actuators are based on REYQ16M.
<Defrost starting condition>
Defrost operation is started when the outdoor heat exchanger temperature becomes lower than deicer temperature.
Defrost operation is conducted once in max. 2 hours.
Actuator
Defrost preparation
operation
Defrost operation Post-defrost operation
Compressor Upper limit control 143 Hz + ON + ON
1-step increase from
(74Hz + OFF + OFF) to
(Pc - Pe > 0.4 MPa)
Outdoor unit fan
STEP8
or
STEP9
OFF STEP9
Four way valve 1 Heat exchange mode OFF ON
Four way valve 2 Heat exchange mode OFF OFF
Main motorized valve (EV1)
Four way valve 1
OFF:1400 pls
ON:SH control
1400 pls 180 pls
Sub motorized valve (EV2)
Four way valve 2
OFF:1400 pls
ON:SH control
1400 pls 1400 pls
Sub-cooling motorized valve (EV3) 0 pls 0 pls 0 pls
Hot gas bypass valve (SVP) OFF ON ON
Oil equalization valve (SVO) ON ON ON
Receiver gas charging valve (SVL) OFF OFF OFF
Receiver gas discharge valve (SVG) OFF OFF OFF
Discharging pipe stop valve (SVR) ON OFF OFF
Non-operating unit liquid pipe stop
valve (SVSL)
ON OFF OFF
High pressure gas pipe pressure
reduction valve (SVC)
OFF ON ON
Ending conditions 2 min.
•
12 min.
•
Tb >11
°
C
•
160 sec.
•
Pc - Pe>0.4MPa
or or
Indoor unit actuator During defrost
Fan
Cooling Thermostat ON unit Set Fan Speed
Heating Thermostat ON unit OFF
Stopping unit OFF
Cooling Thermostat OFF unit Set Fan Speed
Heating Thermostat OFF unit OFF
Electronic expansion valve
Thermostat ON unit 512 pls
Stopping unit 512 pls
Thermostat OFF unit 512 pls