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SiBE04-624_B
2.7
Draft Prevention Control (Hot-Start Function)
Outline
Draft prevention control prevents cold draft when the unit is started up in heating operation. This
function is activated when the indoor heat exchanger temperature drops.
Detail
Draft prevention control is conducted by monitoring indoor heat exchanger temperature. When
the indoor heat exchanger temperature drops below 33°C, the minimum frequency of the
compressor increases.
When the indoor heat exchanger is not hot enough, the indoor fan does not start at the set
speed. The fan speed increases step by step. The limitation of the fan speed is lifted when the
indoor heat exchanger temperature rises above F°C.
28 class
42/50 class
2.8
Dew Prevention Control
Outline
Cooling the air around us means that the air is dehumidified (condensation of water on the
indoor heat exchanger). But because the air is cooled down, less moisture can present in the air
and as a consequence the relative humidity of the air rises. When the relative humidity of the
outlet air nears 100%, water may be blown out. To prevent this from happening, the unit
changes, its target evaporating temperature and the frequency of the compressor under certain
circumstances. Normally speaking, even under these conditions (dew prevention safety active),
the room should still be cooled down, only slower. Of course, if the capacity of the indoor unit is
small in comparison to the heat load, this is not the case and capacity shortage complaints may
follow.
Detail
Function and Control
35˚C
33˚C
Fan speed
M
ML
Upper
L
limitation
LL
LLL
A (°C)
10
10
When the indoor heat exchanger temperature is lower than the target temperature of the
indoor heat exchanger, the compressor frequency decreases by 2 Hz in every minute.
The target temperature of the indoor heat exchanger is calculated with the room temperature
and the indoor humidity.
Minimum frequency – 2 Hz / 120 seconds
No change (steady area)
Minimum frequency + 4 Hz / 120 seconds
A
B
C
D
E
B (°C)
C (°C)
25
33
25
35
Control Specification
(R5912)
No limitation
F
Temperature
(˚C)
D (°C)
E (°C)
34
35
37
38
(R18150)
F (°C)
36
39
61
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