Defrosting Operation - Daikin Super Multi Plus D-Series 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 (EV2)
Hot gas bypass valve (SVP)
Receiver gas discharging valve
(SVG)
Ending conditions
* From the preparing operation to the defrost operation, and from the defrost operation to the
operation after defrost, the compressor stops for 110 sec. to reduce noise on changing of the
four way valve.
Indoor unit fan
BP unit electronic expansion
valve
64
Outdoor heat exchanger heat transfer co-efficiency
Temperature of heat-exchange (Tb)
Low pressure equivalent saturation temperature (Te)
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
ON → OFF
130 sec.
Indoor actuator
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Defrost operation
140 Hz
OFF
OFF
2000 pls
0 pls
ON
ON → OFF
• Max. 18 min.
or
• Tb >11°C
During defrost
SiEBE18-526
Post Defrost operation
2-step increase from
52 Hz to
(Pc - Pe>0.4 MPa)
every 20 sec.
STEP8
ON
200~400 pls
0 pls
ON
ON → OFF
• 160 sec.
or
• Pc - Pe>0.4MPa
OFF
OFF
OFF
SH control
80 pls
SH control
Function