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

Case/room controller (eev)

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AK-CC55 Compact

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)

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

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.

At natural defrost, the ice is melted by running the fans and thereby circulating warm air through the evaporator.

Figure 15: Natural defrost

A defrost can be started in different ways:

Interval:

Defrost is started at fixed 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 fixed times of the day and night. However, max. 6 defrosts per day.

Contact:

Defrost is started with a contact signal on a digital input.

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