Defrost Mode - Daikin LX10F11B Service Manual

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1.4.4 Defrost Mode

●Hot-Gas Defrost System
A hot gas system is adopted for the heat source;
I.e. the high temperature and high pressure
refrigerant discharged from the compressor is
supplied to the evaporator and drain pan for
defrosting. Since the ice built on the evaporator
is directly and evenly heated up from the inside,
defrosting can be efficiently performed.
●Display
"DEFROST" is displayed
on the upper right of the
screen.
●LED display
The DEFROST indicator (orange) lights.
●Defrost operation
The pump-down operation is executed by closing
EEV and opening DMV first.
Then the defrost operation will start by closing
DMV and opening HSV and hot gas is supplied to
the evaporator and drain pan. During defrosting,
the compressor speed is adjusted in order to
maintain the optimum hot gas temperature. (High
Pressure Constant Control). Release control
(DMV open, CFM ON) or charge control (ESV and,
EMV open) may be carried out depending on the
operating conditions. After termination of defrosting,
normal temperature control operation will start.
However, the delay timer will cause the evaporator
fan to remain stopped for a maximum of 3 minutes.
●In-Range masking
The control temperature temporarily becomes out-
rage during defrosting, but the IN RANGE LED is
kept ON.
This will avoid misunderstanding that there will be a
problem if the IN RANGE LED is turned OFF.
Evaporator
Reheat coil (option)
LPT
HPT
HPS
Compressor
●Defrost Initiation
Pull-down
In-Range
Manual Defrost
▲
▼
●Defrost Initiation Conditions
Defrost interval (Frozen)
Short timer
Out-range timer
Manual defrost
Defrost interval (Chilled)
If the initiation conditions are not satisfied when
timer counts down, the defrosting will not be
initiated. If "AUTO" is selected, defrosting will be
executed automatically in accordance with the
accumulation of ice on the evaporator coil.
●Defrost Termination Conditions
Defrosting Time
EFM
EEV
PRV
HSV RSV
CFM
DMV
Condenser
Receiver
1-14
6Hr
Short timer
（12Hr when RS<-15℃）
When supply air temperature does not
Automatic
drop 0.2℃ per 1 hr in frozen mode.
detecting
"AUTO"
Defrost
Defrost interval setting
interval
"3, 6, 9, 12 or 24" Hr
setting
Executed by 30 min. timer
Out-range
after the control temperature
timer
rises out of in-range.
Executed by Manual defrost key.
Timer Count-down
Termination Conditions
EOS≧20℃
＜45 minute & (RS≧5℃ or RS≧5℃ with 10 min.
elapse if RS<-20℃ at defrost initiation)
EOS≧25℃
≧ 45 minute & (RS≧15℃ or RS≧5℃ with 10 min.
elapse if RS<-20℃ at defrost initiation)
Defrost is forcibly terminated at
90 minute
90 minutes. (E207）
EMV
ESV
LSV
Sight glass
Initiation Conditions
EOS≦20.0℃
EOS≦20.0℃
& EIS<5.0 ℃
Economizer
Dryer