Hitachi RAS-8FSXN - Defrost Operation

5.2.8 Defrost operation
No
Yes Big
Small
Heating
Defrosting
RVR2 : OFF
RVR1 : ON
RVR1 : OFF
Outdoor FAN MOF1 : OFF
Temperature Difference
betw
ee
n Outdoor Temperature
and Evaporating Temperature (Te)
at Heat Exchanger
Heating Operation Time
40 Minu
tes or Above
No No
Yes
No
Yes
Discharge Gas Pressure
is 1.7MPa or Above
Evaporating Temperature
(Te) at Heat Exchanger is
1
5ºC or Above
Yes
Defrosting Time is
9 Minu
tes or Above
Defrosting
Completion
Heating
Fixed Opening
Deg
ree of Electronic
Expansion
Valve
PID Control for
Super Cooling Electronic
Expansion
Valve
RVR2 : ON
Compressor Operating
at Low Frequency
High Frequency
O
p
eration
1 Minute Later
(1)
The
defrost signal is transmitted to the indoor unit during the defrost operation. After the signal is received, the remote
control liquid crystal display indicates DEFROST and the indoor unit fan stops.
(2)
For heat recovery systems with 20 HP or more, the RVR1 reversing valve will not operate.
(3)
For heat recovery systems with 20 HP or more, switching power ON/OFF of the RVR2 reversing valve will be carried out
in each outdoor unit.
5 Control system
104
SMGB0065 rev. 1 - 12/2010