Danfoss AK-CC55 Compact - Defrost; Electrical Defrosting; Simple Hot Gas Defrosting; Natural Defrost

Defrost
Depending on the application, you may choose between the following defrost methods:
• Natural: Here the fans are kept operating during the defrost
• Electric: The heating element is activated
• Hot gas: Simple hot gas defrost can be selected in application modes where a compressor is controlled. The
compressor unit will operate during defrosting
• Brine defrost: The brine valve is forced open while defrosting (only possible when selecting modulating control in
TXV applications)
Electrical defrosting
At electrical defrost, an electrical heater is placed in front of the evaporator and the fan will “pull” the hot air through
the evaporator during defrosting.
Figure 14: Electrical defrosting
Danfoss 84B8330
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Simple hot gas defrosting
If hot gas defrost is selected in application 1-5, the compressor will be running during defrost and a hot gas valve
(HGV) is bypassing the compressor discharge gas to the evaporator inlet and thereby the evaporator is defrosted.
Natural defrost
At natural defrost, the ice is melted by running the fans and thereby circulating warm air through the evaporator.
Figure 15: Natural defrost
Danfoss 84B8331
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Start of defrost
A defrost can be started in dierent ways:
Interval:
Defrost is started at xed time intervals like e.g. every eighth hour. An interval must ALWAYS be set to a "higher"
value than the period set between two defrostings when a schedule or network signal is used.
Week schedule:
Here defrost can be started at xed times of the day and night. However, max. 6 defrosts per day.
Contact:
Defrost is started with a contact signal on a digital input.
AK-CC55 Compact
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