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DEFROSTING
- Areversing vaive defrosting format is used, and the defrosting cycle consists of [balancing period of 90 seconds when defrosting starts -> reverse
cycle period for 12 minutes maximum -> balancing period of 90 seconds when defrosting stops] . Since this system uses the outdoor heat-exchanger
concurrently in two cycles, defrosting is executed for both cycles during 2-cycle heating operation.
(1) Defrosting start conditions
- Defrosting i performed when ail the following conditions are satisfied (however, this does not apply when a defrosting request from another cycle
is received.):
:
For normal operation
Heat-exchanger low temperature (heat-exchanger temperature
= DEF. > ON)
When defrosting inhibit time is up {instructed by EEPROM [FLGSET (3.2.1)j and set when normal operation is started)
(2) Defrosting stop conditions
* Defrosting is released when either of the following conditions is established (however, defrosting will continue when a defrosting request from
another cycle is received.):
Heat-exchanger temperature is recovered (heat-exchanger temperature = DEF.
> OFF)
When maximum defrosting time (12 minutes) is up
3 Release during balancing at start: To be returned to normal when remaining balancing time is up.
Release during reverse cycle period: To be returned to normal when balancing time (90 seconds) is up at the end.
(3) Qutputs during defrosting
:
| Defrosting request between outdoor microcomputers] To be transferred only when heat-exchanger low temperature is detected and
defrosting
ts being executed.
[Indoor
defrosting request] To be transferred to all units which are in heating operation.
[Compressor] To increase the speed at the rate of DFSTEP mm/TDFSPT second and reach the maximum defrosting speed [DEFMAX].
[Expansion valves] Units with compressor off: To be fully closed when defrosting starts and the balancing time (30 seconds) is up.
Units with compressor on: To be opened by [DFSPPS]| pulses, synchronized with a step-up of rotation speed, and fully
opened [DFPSMX] when the speed reaches [DEFMAX].
Kit ree is no compressor on machine in one cycle, the above control can be performed by turning the operation bit on
and off.
(4) Special remarks
* During one-cycle heating operation, defrosting should be executed with one cycle only. Other cycles should remain in the stop mode.
' During
2-cycle heating operation, defrosting is released and finished for both cycles.
Therefore, each period may exceed the specified time.
' If unit fails and stops while defrosting is being executed by a defrosting request issued from another cycle, defrosting will be executed from start (for
balancing 90 seconds) after balancing 3 minutes are up and failure is released.
During one-cycle heating operation
Detrosting signal
Detrosting request between
Ouldoor microcomputers
j
, | ee |
FESS 7 nN
SSE ET
GS
Defrosting request to another cycle
: Defrosting reques'
mm
ee
TSKTML
®@ Defrosting
sequence
TEP ame
DEFMAX
\
DFS
TDFSPT s
Start sequence
,
—
Compressor
rotation speed
SDRCT1
weer
ee gree
DFCTPS
DFPSHX
ee
ere:
ere
DFCTPS
%€ - See other sections for details of expansion valve TD control, AN correction and distribution control.
- DEF-ON, DEF-OFF, TSKTM1, SDRCT1, TDFSPT, DFSTEP, DEFMAX, PSTART, DFCTPS, DFSPPS and FLGSET are EEPROM data.
- 112 -
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