Hitachi RAS-(3-6)HVNC1(E) - Defrost Operation Control; Defrosting Operation

5 Control System
152
SMGB0087 rev.0 - 12/2013
5.4.5 Defrost operation control
Heating
operation
Yes
De-
frosting start
condition
No
DEFROST indication
Power to MIF: OFF
Power to MOF: OFF
Power to
YH2: ON
Power to EHW: ON
For unit with
EHW
Power to RVR: OFF
Defrosting
operation
De-
frosting stop
condition
No
Yes
Power to
MC: OFF
Power to
MC: ON
After
30 seconds
After
90 seconds
*
Power to
RVR: ON
No No
Yes
Yes
* DSW-1 ON (and DSW2-2 ON for RAS-2.5HVNP)
RAS-(2-2.5)HVNP / RAS-3HVNC
Power to RVR: ON
Yes
Other than above
DEFROST desappears
IU
demand
frequency
> 90 Hz
Power to
YH2: OFF
Power to
YH2: ON
For unit with EHW
Power to EHW: ON
≥ 90 Hz
IU
intake air
temp.
IU fan operation: LOW
Power to MC: OFF
Higher than set
temperature + 2ºC
IU
intake air
temp.
Operation at setting fan speed MIF
≥ 30ºC
Lower than set
temperature
+ 2ºC
25ºC to 30ºC
< 25ºC
Operation at low
fan speed MIF
Operation at
slow fan speed MIF

Defrosting Operation
The following defrosting operations, “Standard Defrost”, “Forced Defrost” and “Manual Defrost” are available.
1 Standard Defrost
This operation is started according to the outdoor temperature, the outdoor evaporating temperature and operating time.
2 Forced Defrost
This operation starts when the indoor unit is operated Thermo-ON/OFF repeatedly and the standard defrost is not used.
3 Manual Defrost
This operation starts when the push switch “PSW1” on the outdoor PCB is pressed and hold for more than 3 seconds du-
ring the maintenance work. (It is not performed when the defrosting operation is started, the high pressure and the outdoor
evaporating temperature is high.)
 N O T E
Donotrepeatdefrostoperationfrequently.