Outline Of Heating Operation - Mitsubishi Heavy Industries SRK20ZIX-S Service Manual

1.6.9 Outline of heating operation

(1) Operation of major functional components in heating mode
Compressor
Indoor fan motor
Outdoor fan motor
4-way valve
(2) Details of control at each operation mode (pattern)
(a) Fuzzy operation
Deviation between the indoor temperature setting correction temperature and the return air temperature is calculated in
accordance with the fuzzy rule, and used for control of the air capacity and the compressor speed.
Fan speed
Auto
HI
MED
LO
When the defrosting, protection device, etc. is actuated, operation is performed in the corresponding mode.
(b) Hot keep operation
If the hot keep operation is selected during the heating operation, the indoor blower is controlled based on the temperature
of the indoor heat exchanger (Th) to prevent blowing of cool wind.
(3) Defrosting operation
(a) Starting conditions (Defrosting operation can be started only when all of the following conditions are met.)
) After start of heating operation
When it elapsed  (model 0, 0 : ) minutes. (Accumulated compressor operation time)
) After end of defrosting operation
When it elapsed  (model 0, 0 : ) minutes. (Accumulated compressor operation time)
) Outdoor heat exchanger sensor (TH) temperature
When the temperature has been below － ºC for  minutes continuously.
) The difference between the outdoor air sensor temperature and the outdoor heat exchanger sensor temperature
¡ The outdoor air temperature ≧ 0ºC (model 0, 0 : ≧ － ºC) : ºC or higher
¡ － ºC ≦ The outdoor air temperature ＜ 0ºC (model 0, 0 : ＜ － ºC) : / × The outdoor air temperature + ºC
or higher
¡ The outdoor air temperature ＜ － ºC : － ºC or higher
) 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 0 times or more and all conditions of ), ), ) and ) above and the outdoor air temperature is ºC or less are
satisfied (note that when the temperature for outdoor heat exchanger sensor (TH1) is － ºC or less:  rps or more,
－ ºC or less: less than  rps), defrost operation is started.
(b) Ending conditions (Operation returns to the heating cycle when either one of the following is met.)
) Outdoor heat exchanger sensor (TH) temperature: ºC (model 0, 0 : 0ºC) or higher
) Continued operation time of defrosting → For more than 15 min.
Thermostat ON
ON
ON
ON
ON
Model
SRK20ZIX-S
30~94rps
30~94rps
30~66rps
30~40rps
Heating
Thermostat OFF
OFF
ON(HOT KEEP)
OFF
(few minutes ON)
ON
(3 minutes ON)
SRK25ZIX-S SRK35ZIX-S
30~102rps 30~115rps
30~102rps 30~115rps
30~72rps 30~76rps
30~42rps 30~46rps

- -
Failure
OFF
OFF
OFF
OFF
SRK50ZIX-S
12~106rps
12~106rps
12~74rps
12~42rps
SRK60ZIX-S
12~120rps
12~120rps
12~90rps
12~58rps