Defrosting Operation - Daikin LXE10E-A18C Service Manual And Parts List

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3. DEFROSTING OPERATION

(1) Defrosting system
A hot-gas defrost system is adopted in the units; i.e. the high temperature and high pressure refrigerant
(hot gas) from the compressor is sent to the evaporator and drain pan for defrosting. Since the evaporator
is heated directly by the hot gas (refrigerant), defrosting can be performed effectively.
(2) Defrosting initiation
Defrosting is initiated by the timer or the manual defrost key.
However, defrosting is not initiated when frosting on the evaporator can not be detected.
Evaporator inlet temperature : 5˚C or higher (during chilled operation)
¡
¡ Evaporator outlet temperature : 20˚C or higher
qInitiation by timer (Timer is set at the electronic controller, refer to section 3.3.2 of service manual for its
operating method.)
Type of timer
Long timer
Short timer
Out-range timer
※1. On-demand defrost selection (12 hours for Frozen mode and 6 hours automatic for Chilled mode)
※2. 6 hours when the control temperature is –20˚C or below.
wStarting by MANUAL DEFROST key (on the operation panel sheet key)
Press the MANUAL DEFROST key, then press the ENTER/ESC key while indicate "ON" on the LED
display. The manual defrosting operation starts.
eInitiation by frost detection
If the suction air temperature does not drop at the speed of 0.2˚C/1hr during frozen pull-down
operation, defrosting will be initiated because it is judged that frost is formed on the evaporator.
However, if the suction temperature is –20˚C or lower, defrosting will not be initiated. (activated)
(3) On demand defrost setting
When "99" in long timer is selected, defrosting is activated upon the condition of frost on evaporator
coil. This function is only for Frozen setting (SP < –10.1 deg C). and starting with 12 hours.
(If this function is selected for chilled setting, defrost initiates every 6 hours automatically.)
Procedure:
Step 1: After defrost, the controller records compressor running time for 1
Step 2: When 12 hours passed after defrost, controller records compressor running time for last 1
hour (T2). And the controller check whether the below condition is satisfied.
Step 3: If the above condition is satisfied, defrost is activated.
If above condition is not satisfied, defrost is postponed another one hour.
After counting up 13 hours, then repeat "Step 2".
Defrost will be postponed every one hour until the above condition (Step 2) is satisfied.
(Max. 24 hours)
Defrosting interval set
3, 6, 9, 12, 24 and 99 ※1 hours are
selectable
Optional function setting mode:
If the"AUT-INT"is set to ON, the set time
may be changed. For details, refer to
information in"defrosting interval automatic
changing function"
(on page 10).
4 hours ※2
30 minutes
T2 > T1×1.15
Regardless of the control temperature,
defrosting is initiated according to the
selected interval.
Defrosting is initiated every 4 hours until the
control temperature comes within the in-
range after pull-down.
After the control temperature comes within
in-range once, defrosting will be started 30
minutes later if the control temperature
rises out of the in-range.
11
Function
st 1 hour. (T1)