Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 140

SCM-HG (4 room)
(d) Refrigerant pooling protection control
This function prevents the pooling of refrigerant in the indoor unit when stopped during heating operation.
1) Operating conditions (When all of the following conditions are met, the refrigerant pooling protection control
operation will start.)
1 When heating.
2 After start or operation or 4 hours after end of this
control (Cumulative actual operating time of com-
pressor at outdoor unit frequency of 16 Hz or more).
2) Description of control
Outdoor unit frequency
Solenoid valve
(SVA, B, C, D)
[Operating units]
Solenoid valve
(SVA, B, C, D)
[Stopped units]
Electronic expansion valve
(EVA, B, C, D)
[Operating units]
Electronic expansion valve
(EVA, B, C, D)
[Stopped units]
Outdoor fan
Solenoid valve
(SVDf)
(e) Refrigerant flow noise reduction control
This control operates to control the refrigerant flow noise created when the number of indoor units is increased (1 → 2, 2 →
3, 3 → 4). (Note that this does not apply when increasing from 0 → 1).
1) If one indoor unit is going to be added.
Outdoor unit frequency
Solenoid valve
(SVA, B, C, D)
[Operating units]
Solenoid valve
(SVA, B, C, D)
[Stopped → Operating units]
Solenoid valve
(SVA, B, C, D)
[Stopped units]
Electronic expansion valve
(EVA, B, C, D)
[Operating units]
Electronic expansion valve
(EVA, B, C, D)
[Stopped → Operating units]
Electronic expansion valve
(EVA, B, C, D)
[Stopped units]
Outdoor fan
Solenoid valve
(SVDf)
138
Decision frequency
16 Hz
ON
OFF
ON
OFF
According to decision frequency
ON
OFF
Stopped unit ON
Decision frequency
ON
OFF
ON
OFF
ON
OFF
According to decision frequency
According to decision frequency
ON
OFF
3
When the compressor is operating.
All opened
75 pulses
2 minutes 30 seconds 2 minutes 30 seconds
16 Hz
All opened
75 pulses
75 pulses
2 minutes
34 Hz
According to
decision
frequency Hz
All opened
According to
decision
According to 16 Hz
frequency Hz
30 seconds