Hitachi RPC-1.5FSR Technical Catalogue page 77

<Condition for Starting Defrost>
(1) Standard Defrost
(a) Temperature Condition
Temperature
Condition
under
Defrosting
Operation
(b) Condition for Operating Time of Defrosting Operation Start
The defrosting operation starts when the temperature condition shown in "(a) Temperature
Condition" is met after the heating operation is performed for 40 to 120 minutes. The heating
operation time is determined by estimating the amount of frost on the heat exchanger.
(2) Forced Defrost
< Condition for Starting >
The forced defrosting operation starts when all the following conditions are met.
(a) The reversing valve is "ON" for more than 120 minutes.
(b) The outdoor temperature is lower than 10
(c) The accumulated heating operation time is more than 60 minutes.
(The accumulated time is reset when the operation is stopped or the defrosting operation is
performed.)
(d) The compressor is operated continuously for more than 1 and a half minutes.
(e) The outdoor evaporating temperature is lower than 5
(f) The pressure switch for control is "OFF".
<Condition for Completing Defrosting Operation>
The defrosting operation stops when any of the following conditions is met.
(1) The outdoor evaporating temperature reaches more than 25
operation starts.
(2) The outdoor evaporating temperature reaches more than 15
2 minutes after the defrosting operation starts.
(3) The outdoor evaporating temperature reaches more than 5
2 minutes after the defrosting operation starts.
(4) The pressure switch for control is "ON".
(5) More than 9 minutes pass after the defrosting operation starts.
NOTE:
The defrosting operation does not start immediately even if the above conditions are met.
(The defrosting condition may be met temporarily depending on the refrigerant cycle variability.)
The defrosting operation starts when the conditions are met continuously for a period of time.
TCI-20007-rev.1
15
Outdoor
Evaporating
10
Temp. ( C)
o
(Pipe)
5
-15 -5
-10 5 6 10
0
-2
Outdoor
-5
Temp. ( C)
o
-6.7
Defrosting
-10
Operation
Start Area
-15
o C.
Defrosting
Operation
Stop Area
15
o
C right before the operation starts.
o
C for 2 minutes after the defrosting
o
C (the outdoor temperature < 10
o C (the outdoor temperature > 10
CONTROL SYSTEM
o
C)
o C)
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