Daikin UATYA-B, Operation Manual

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Service manual Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
3.17.6 Management of auxiliary heating during defrost cycle
Irrespective of the auxiliary heating type in the unit, the controller can enable it during the defrost cycle to preserve comfort
in the room, where this is required for winter operation.
The controller outputs the demand to the auxiliary heating function at the percentage value set in parameter “STH132”.
3.17.7 Special management logics during defrosting
There are some operating modes during which the controller adjusts ventilation in a special way.
3.17.7.1 Ventilation management during defrosting
For enhanced room comfort during the defrost cycle, the fan in the delivery line follows the setpoint in parameter “FA81”.
This only applies when either a constant or variable flow control is featured and parameter “FA82” is set to “1”.
For enhanced room comfort during the defrost cycle, the fan in the return line follows the setpoint in parameter “RFA31”.
This only applies when constant flow control is featured or when variable flow control is featured in the delivery line and
parameter “RFA32” is set to “1”.
Reduced air flow during the defrost cycle enhances room comfort, but it also reduces the efficiency of the
defrost cycle.
Great attention should be paid when setting reduced flow parameters.
Very low flow values may cancel the defrost cycle efficiency.
3.17.7.2 Management of external air damper during defrosting
For continuous comfort in the room, the external air and exhaust air dampers can be overridden to close using the value
set in parameter “DA14”. This is the case when defrosting takes place reversing the refrigeration cycle, for as long as the
coil of the 4-way valve in the refrigerant circuit is de-energised. As a consequence, the recirculated air damper is fully open.
3 Software functions