Standard Control Functions; Freezing Protection During Cooling Process Or Dry Operation - Hitachi RASC-4HNPE Service Manual

5 Control system

Standard control functions

5.4 Standard control functions

5.4.1 Freezing protection during cooling process or dry operation

Anti-freeze control depends on 2 conditions:
CONDITION 1:
Cooling or dry
operation
No
operated for more
Higher than 0 ºC
surface temperature of
indoor heat exchanger
No
Is it continuous for
more than 3 min.?
Compressor and indoor
Gas or liquid pipe
surface temperature of
indoor heat exchanger
temperature of indoor
89 SMGB0091 rev.2 - 11/2015
Power supply
Is compressor
than *30 min.?
*) The check interval differs
Yes
depending on the conditions
Gas or liquid pipe
Lower than 0 ºC
Yes
unit fans OFF
Lower than
11ºC
Higher than 11 ºC
Lower than
Liquid pipe
2 ºC
heat exchanger
Higher than 2 ºC
CONDITION 2:
Power supply
Cooling or dry
operation
Higher than 25 ºC
Outdoor ambient
temperature
Gas or liquid pipe
Higher than 2 ºC
surface temperature of
indoor heat exchanger
No
Is it continuous for
more than 60 min.?
Yes
Compressor and indoor
unit fans OFF
Gas or liquid pipe
surface temperature of
indoor heat exchanger
Liquid pipe
temperature of indoor
heat exchanger
Lower than 25 ºC
Lower than 2 ºC
Lower than
11ºC
Higher than 11 ºC
Lower than
2 ºC
Higher than 2 ºC
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