Mitsubishi Heavy Industries SRRM40HENG-L, Handbook, Page: 23 / 1106

21
SRK-GZ
(v) Defrosting operation
S
Models SRK25GZ-L1, 35GZ-L1
1) Starting conditions (Defrosting operation can be started only when all of the following conditions are met.)
¡
Model SRK25GZ-L1
1
After start of heating operation
→
When it elapsed 40 minutes. (Accumulated operation time)
2
After end of defrosting operation
→
When it elapsed 40 minutes. (Accumulated compressor operation time)
3
Outdoor unit heat exchanger thermistor (Th5) temperature
→
When the temperature has been below –3ºC
for 3 minutes continuously.
4
When there is a big temperature difference between the outdoor unit heat exchanger thermistor (Th5) and
the outdoor air temperature thermistor (Th6).
5
When the compressor is operating.
Moreover, the defrosting operation starts when the frequency command released from the indoor unit con-
troller has counted 0 Hz for more than 10 times and when all conditions of 1 , 2 and 3 above (however,
temperature of Th5 at –3ºC or under) are met.
OFF
OFF
ON
OFF
ON
116Hz
34Hz
Outdoor
Indoor
Indoor fan
Depending on
frequency
Flash
Note (1) Frequency command is released
from the outdoor controller during
defrosing operation.
10˚C or 15˚C at end of defrosting, or 10 min.
Operation after end
of defrosting
100 sec.
Defrosting
operation
Defrost ON
operation
80 sec.
Fuzzy calculation
value
Outdoor fan
Inverter command
frequency
Operation lamp
Depending on
frequency
4-way valve
Note (1) Steps marked with ( ) of indoor
blower are subject to the hot keep
control.
3) Ending conditions (Operation returns to the heating cycle when either one of the following is met.)
1
Outdoor heat exchanger thermistor (Th5) temperature: 10ºC or 15ºC or higher
2
Continued operation time of defrosting
→
For more than 10 min.
¡
Model SRK35GZ-L1
1
After start of heating operation
→
When it elapsed 40 minutes. (Accumulated operation time)
2
After end of defrosting operation
→
When it elapsed 40 minutes. (Accumulated compressor operation time)
3
Outdoor unit heat exchanger thermistor (Th5) temperature
→
When the temperature has been below –5
°
C
for 3 minutes continuously.
4
Outdoor air temperature thermistor (Th6) - Outdoor unit heat exchanger thermistor (Th5) temperature
0.44
×
Outdoor air temperature thermistor tempe 9ºC or higher
5
When the compressor is operating.
Moreover, the defrosting operation starts when the frequency command released from the indoor unit con-
troller has counted 0 Hz for more than 10 times and when all conditions of 1 , 2 and 3 above (however,
temperature of Th5 at –3ºC or under) are met.
2) Operation of functional components during defrosting operation