Operation Control Function By The Outdoor Control - Mitsubishi Heavy Industries SRR25ZJ-S Technical Manual

(4) Operation control function by the outdoor control
(a) Defrosting operation
Starting conditions (Defrosting operation can be started only when all of the following conditions are met.)
(i)
1) After start of heating operation
When it elapsed 45 minutes. (Accumulated compressor operation time)
2) After end of defrosting operation
When it elapsed 45 minutes. (Accumulated compressor operation time)
3) Outdoor heat exchanger sensor (TH1) temperature
When the temperature has been below –5ºC for 3 minutes continuously.
4) The difference between the outdoor air sensor temperature and the outdoor heat exchanger sensor temperature
¡ The outdoor air temperature ≧ 0°C : 7°C or higher
¡ -15°C ≦ The outdoor air temperature ＜ 0°C : 4/15 × The outdoor air temperature + 7°C or higher
¡ The outdoor air temperature < -15°C : -5°C or higher
5) During continuous compressor operation
In addition, when the speed command from the indoor controller of the indoor unit during heating operation
has counted 0 rps 10 times or more and all conditions of 1), 2), 3) and 5) above and the outdoor air tempera-
ture is 3°C or less are satisfied (note that when the temperature for outdoor heat exchanger sensor (TH1) is -5
°C or less: 62 rps or more, -4°C or less: less than 62 rps), defrost operation is started.
(ii) Ending conditions (Operation returns to the heating cycle when either one of the following is met.)
1) Outdoor heat exchanger sensor (TH1) temperature: 13ºC or higher
2) Continued operation time of defrosting → For more than 16 minutes and 50 seconds.
Models 20～35
0
-5
-10
-15
-20
-20
¡Defrost operation
Heating operation
Depends on an operation condition, the time can be longer than 7 minutes.
Defrost operation
start
-15 -10 -5 0
Outdoor air temperature (℃)
Max. 16 minutes and 50 seconds
69
- -
'14 • SR-T-157
Model 50
0
-5
-10
-15
-20
5 10 -20 -15
2~7 minutes
Hot keep operation
Defrost operatio
start
-10 -5 0 5
Outdoor air temperature (℃)