Daikin UATYA-B, Operation Manual

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Service manual Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
3.17 Defrosting
During operation in heat pump mode, defrosting is the process used to prevent frost build-up on the condensing/evapora -
ting coil and/or to remove any frost that may have formed.
An effective defrost cycle ends with a completely clean condensing/evaporating coil.
The controller manages defrosting differently according to the settings made and the air temperature conditions.
The parameters concerned are shown in the table.
Parameter Min Max UM Description
DF1 0 2 - Defrost method
DF2 0 4 - Defrost entry method
DF3 0 4 - End-of-defrost exit method
DF10 -50.0 110.0 °C Fixed evaporating threshold to start defrost
DF11 0 999 s Defrost start delay
DF12 -1.00 1.00 - Moving defrost - Parameter A with full load
DF13 -100.0 100.0 - Moving defrost - Parameter B with full load
DF17 0 999 min Delay to defrost after the unit is switched on
DF18 0 999 min Time interval between two defrost cycles of the same circuit
DF19 0 999 min Time interval between two defrost cycles of different circuits
DF20 0 1 - Enable manual defrost - from keypad
DF21 -50.0 110.0 °C Evaporating temperature threshold for activating a forced defrost
DF22 0 999 s Delay time for forced defrost
DF25 -5.0 25.0 °C Max. setpoint for defrost start (DF10 + DF25)
DF30 0 2 - Defrost entry method
DF31 0 999 s Forcing time of circuit at 100% on entering defrost mode (if DF30 = 0)
DF32 0 999 s Forcing time of circuit at minimum on entering defrost mode (if DF30 = 1)
DF33 0 999 s Forcing time of circuit OFF on entering defrost mode (if DF30 = 2)
DF34 -50.0 110.0 °C Outside air temperature limit for air defrost
DF49 -50.0 110.0 °C End-of-defrost threshold for condensing temperature
DF50 1 360 s Minimum defrost duration time
DF51 90 999 s Maximum defrost time
DF52 33 88 % Inverter - Pre defrost percentage
DF53 33 88 % Inverter - Percentage during defrost
DF54 33 88 % Inverter - Percentage after defrost
DF61 0 2 - Defrost exit method
DF62 0 999 s
Time compressors are with capacity reduction during end of defrost (if DF61
= 1)
DF63 0 999 s Time compressors are OFF during end of defrost (if DF61 = 2)
Activation of simultaneous or separate defrost of the refrigerant circuits and the start conditions at fixed or
sliding evaporating pressure are done at the factory.
The stages of a defrost cycle are as follows:
- check of defrost start conditions (at fixed or sliding evaporating pressure);
- check of type of defrost to carry out (with air or with refrigeration cycle reversal);
- preparation for cycle reversal;
- refrigeration cycle reversal and defrost of the condensing/evaporating coil;
- check of complete defrosting;
- preparation and new cycle reversal with return to operation in heating mode.
To complete defrost management, in addition to the main stages, the controller gives the possibility of manual forcing by
operators or automatic forcing when particular conditions occur.
For optimised defrosting and constant comfort in the rooms the controller can adjust the dampers and the air flow rate.
3 Software functions