Hitachi UTOPIA RAS-4HVRP2E - Freezing Protection During Cooling Process or Dry Operation; Standard Control Functions

5 Control System
Standard control functions
SMGB0136 rev.0 - 07/2021
103
5
5.6 Standard control functions
5.6.1 Freezing protection during cooling process or dry operation
Cooling or dry
operation
Is
compressor
operated for more than
30min.
*1)
?
*1)
: The check interval differs
depending on the conditions
MIF operation at set fan speed
(in case of dry operation.
MIF operation: OFF for 6 min.)
Power supply
No
Yes
Gas
or liquid
pipe surface
temperature on heat
exchanger
Lower than 0ºC
Is
it
continuous for
more than 3 min.?
Yes
For individual
operation
IU electronic expansion valve:
completely closed
Is
it
continuous for more
than 3 min.? (6 min in case
of dry operation)
No
Yes
a
Gas or
liquid pipe surface
temp of indoor heat
exchanger
Lower than 14ºC
Higher than 14ºC
15
min
progress
Yes
No
No
Yes
Either
of pipe surface
temp
*2)
> 2ºC
Inverter frequency = 0 Hz
For simultaneous or
single operation
No
Higher than 0ºC
Cooling or dry
operation
*2)
: Pipe surface temperature
NOT adpopted at
a
IU: Indoor unit