Hitachi RAS-(4-12)HNP(1)(E) - Condition for Starting Defrost

5 Control System
153
SMGB0087 rev.0 - 12/2013
5

Condition for Starting Defrost
1 Standard defrost
a. Temperature condition
Model
RAS-(2-2.5)HVNP1
RAS-3HVNC1
RAS-3HVNP1E
RAS-(4-12)H(V)N(P/C)(1)(E)
Temperature
condition under
defosting
operation
-4.6
Defrosting
operation
start area
Defrosting
operation
stop area
Outdoor
temperature
(ºC)
Outdoor evaporating
temperature (ºC)
(pipe)
Defrosting
operation
start area
Defrosting
operation
stop area
Outdoor
temperature
(ºC)
Outdoor evaporating
temperature (ºC)
(pipe)
b. Condition for Operating Time of Defrost Operation Start
The defrosting operation is started when the temperature condition is met “(a) Temperature Condition” after the heating
operation is performed for 40 to 120 minutes. The heating operation time is determined by estimating the amount of fros-
ting on the heat exchanger.
2 Forced Defrost
Condition for Starting
The forced defrosting operation is started when all the following conditions are met.
a. 120 minutes are passed after the reversing valve is “ON”.
b. The outdoor temperature is lower than 10ºC.
c. The accumulated heating operation time is more than 60 minutes. (*1)
(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 half minutes. (*2)
e. The outdoor evaporating temperature is lower than 5ºC (*3) right before starting the operation.
f. The pressure switch for control is “OFF”.
 N O T E
ForRAS-(2-2.5)HVNP1/RAS-3HVNC1:
• (*1)Morethan39minutes.
• (*2)Ifoutdoortemperatureislessthan-6ºCthenthecompressorisoperatedcontinuouslyformorethan2minutes.If
outdoortemperatureismorethan-6ºCthenthecompressorisoperatedcontinuouslyformorethan9minutes.
• (*3)Lessthan6ºC.