CRD-XP
Page 10 of 16 Subject to technical changes CRD-XP_2005-12_EN
5 Fan control – Cooling operation and defrosting
The parameters P28 and P31 can influence ventilator behaviour. P28 is used to set controls in normal
operation, P31 during defrosting.
Continuous operation (P28 = 0)
If parameter P31 is set to "1", the ventilator is triggered without interruption. At position "0", the
ventilator is switched off during defrosting. It is switched on again after any draining (P26) and
ventilator delay time (P32).
Timed ventilator control (P28 =1)
With this ventilator control, the ventilator output is timed with the cooling command, taking into account
the parameters P33 and P34. The ventilator starts in advance of cooling by the time set in P33 and
continues to run after cooling is switched off for the time set in P34.
If the ventilator should be switched off during defrosting, parameter P31 must be set to "0". The
ventilator starts again after defrosting and after the ventilator delay time P32.
Thermostatic ventilator control (P28 = 2)
The ventilator is only switched on when the regulating actual value falls below the temperature set in
parameter P29 minus half the hysterisis (from P30). The ventilator is switched off when the regulating
actual value lies above the temperature set in P29 plus half the hysterisis.
Fan controller
Fan beahaviour
during defrost
T Draining Time
Application
examples
P28
P31
P33
P26
P34
P33
P34
Cool T
Deep-freese cabinet
Defrost Electric/hot gas/cold gas defrost
OFF Fan
Island / Shelf / Counter
Cool T Circulation air/electric/hot gas/cold gas defrost
Defrost
Standard cooling cabinet
ON Fan Circulation air defrost
Timed Cool T
Room
Defrost Electric/hot gas/cold gas defrost
OFF Fan
Cool T
Room
Defrost Circulation air defrost
ON Fan
Thermostatic Cool T
Room
Defrost Electro/hot gas/cold gas defrost
OFF Fan
Cool T
Room
Defrost Circulation air defrost
ON Fan
Continuous
operation
V Run-up time prior
to cooling
N Rundown time
following cooling
P33
P34
P32
LV Fan delay
V Run-up time prior
to cooling
N Rundown time
following cooling
V Run-up time prior
to cooling
VNV
N Rundown time
following cooling
LV
LV
VNV N
VNN
VN
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