SiUS12-928_B
Control Specification
Function and Control
62
3.10 Defrost Control
Outline
Defrosting is carried out by the cooling cycle (reverse cycle). The defrosting time or outdoor heat
exchanger temperature must be more than a certain value to finish.
Detail
Conditions for Starting Defrost
The starting conditions are determined with the outdoor temperature and the outdoor heat
exchanger temperature.
The system is in heating operation.
The compressor operates for 6 minutes.
More than
A
minutes of accumulated time pass after the start of the operation, or ending the
previous defrosting.
Conditions for Canceling Defrost
The target heat exchanger temperature as the canceling condition is selected in the range of
39.2 ~ 53.6°F (
4 ~ 12
°C) according to the outdoor temperature.
18 class: The pulses
E
and
F
are the same.
18 class
24/32 class
A
(minutes)
43
38
B
(Hz)
54
39
C
(Hz)
82
62
D
(seconds)
30
60
E
(pulses)
450
350
F
(pulses)
450
400
G
(pulses)
140
160
Frequency
Compressor
Four way valve
Fan
ON
OFF
ON
OFF
ON
OFF
0 Hz
B
Hz
5 sec.
F
pulses
E
pulses
450 pulses
Initial opening
0 pulse
G
pulses
Initial opening
PI control
5 sec.
D
sec.
60 sec.
530 sec.
120 sec.
(R17363)
C
Hz
Outdoor electronic
expansion valve
opening (operating
room)
Outdoor electronic
expansion valve
opening (stop room)
