Si04-115
General Functionality
Main Function
23
1.4
Defrost Control
Principle
Defrost control is carried out by reversing the cycle from heating to cooling.
Start conditions
Defrost control is set by the following conditions:
"
during heating
"
More than 6 minutes after the compressor has started up
"
when condition 1 or 2 in the table below are applicable:
Conditions
The following table shows the different conditions on which defrost control is based:
Stop conditions
Defrost control is reset by the following conditions:
"
T
[heat exchanger]
> 4°C if T
[ambient outdoor]
< 19°C
"
T
[heat exchanger]
> 18°C if T
[ambient outdoor]
< -3°C
"
T
[heat exchanger]
> (-1°C × T
[ambient outdoor]
) +
C
if -3°C < T
[ambient outdoor]
< 19°C.
Condition
Description
1
"
A
minutes of accumulated runtime
"
not yet 90 minutes of accumulated runtime
"
condition 1 or 2 or 3 in the table below
2
"
90 minutes of accumulated runtime
"
condition 1 or 4 or 5 in the table below
Conditions
Description
1
T
[outdoor heat exchanger]
<
B
°C for 1 min.
2
"
T
[ambient outdoor]
< 5°C
"
T
[outdoor heat exchanger]
< (-5 + T
[ambient outdoor]
× 0.4)
"
check if T
[indoor heat exchanger]
decreases 5 times every 10 seconds
3
"
T
[ambient outdoor]
≥
5°C
"
T
[outdoor heat exchanger]
< -3°C
"
check if T
[indoor heat exchanger]
decreases 5 times every 10 seconds
4
"
T
[ambient outdoor]
<
5°C for 60 seconds
"
T
[outdoor heat exchanger]
< (-5 + T
[ambient outdoor]
× 0.4) for 60 seconds
5
"
T
[ambient outdoor]
≥
5°C for 60 seconds
"
T
[outdoor heat exchanger]
< -3°C for 60 seconds
Class
A
B
C
J type
25
32
-15
17
35
32
-14
17
