Defrosting Operation - Daikin VRV III-S RXYMQ6PV4A Service Manual

Special Control
3.3

Defrosting Operation

The defrost operation is performed to solve frost on the outdoor unit heat exchanger when
heating, and the heating capacity is recovered.
[Conditions to start]
The defrost operation is started referring following conditions.
Outdoor unit actuator
Compressor
Outdoor unit fan
Four way valve
Main electronic expansion valve
(EV1)
Subcooling electronic expansion
valve (EV3)
Hot gas bypass valve (SVP)
Ending conditions
* From the preparing operation to the defrost operation, and from the defrost operation to the
operation after defrost, the compressor stops for 1 minute to reduce noise on changing of the
four way valve.
Fan
Electronic expansion valve
54
Outdoor heat exchanger heat transfer co-efficiency
Temperature of heat-exchange (Tb)
Timer (2 hours at the minimum)
In addition, outdoor heat-exchange co-efficiency is derived from Tc, Te, and the compressor
load.
Defrost preparation
operation
Upper limit control
STEP8
ON
SH control
0 pls
OFF
2 min.
Indoor unit actuator
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Defrost operation
140 Hz Full load
OFF
OFF
480 pls
0 pls
ON
• 15 min.
or • Tb>11°C
{
&
• Ts1 - Te<5°C
Heating oil return operation
SiME34-608
Post Defrost operation
2-step increase from
36 Hz Unload to
(Pc - Pe>0.4 MPa)
every 20 sec.
STEP8
ON
55 pls
0 pls
ON
• 160 sec.
or
• Pc - Pe>0.4MPa
OFF
OFF
OFF
416 pls
256 pls
416 pls
Function