Si33-105
Outline of Control (Outdoor Unit) < Symbols using in this manual >
Function R407C PLUS Series Heat Recovery System
91
3.6.3 Defrost Control
Activates the defrosting operation to melt frost accumulated on the outdoor heat exchanger
during heating operation.
[Defrost start conditions]
When the following conditions are met during heating operation, the defrosting operation is
activated.
Tb : Distributor pipe temperature (°C) at heat exchanger outlet (in cooling operation)
Ta : Outside temperature (°C)
When the above conditions are met, the following “defrosting operation preparation” operation is
conducted for 2 minutes, then the defrosting operation is activated.
1. Outputs “oil return, defrost preparation” signal to indoor units.
2. Turns on the liquid injection solenoid valve (SVT) based on Td or DSH.
Td : Discharge pipe temperature
DSH : Discharge super heat temp.
"
Liquid injection : Refer to page 77.
Note:
Note.1
When compressor stops operation at outdoor temperature >1°C, reset cumulating timer.
OR
&
When cumulative compressor operating time from power On or completion of
previous defrosting operation exceeds 30 minutes Note.1
When condition (Tb
≤
X × Ta – A) remains for 5 minutes (–25
≤
Tb
≤
–10)
(Value of A based on the following table. When Ta
≥
7, Ta = 7°C is used in calculation)
When forced defrost setting (local setting) is turned on and Tb < 12.5°C
Defrost setting
Defrost change
setting
X
L
M
H
No-setting (Factory set) A=12 A=14 A=16
Outside air Ta > 0°C
0.6
Outside air Ta
≤
0°C
0.8
Summary of Contents for R407C PLUS
Page 1: ...System R407C PLUS Series Heat Recovery System Si33 105 Service Manual ...
Page 11: ...Introduction Si33 105 x ...
Page 41: ...Specifications Si33 105 30 Specifications R407C PLUS Series Heat Recovery System ...
Page 147: ...Test Operation Si33 105 136 Test Operation R407C PLUS Series Heat Recovery System ...
Page 263: ...Si33 105 iv Index ...
