Daikin UATYA-B, Operation Manual

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Service manual Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
3.11.3 Capacity reduction override
The unit capacity may need to be limited in some operating conditions.
Capacity limitation may be connected to the pressure values measured on the intake and delivery lines. All parameters
concerning capacity reduction override are shown in the table.
Parameter Min. Max. UM Description
UN5 0.10 99.90 bar High pressure - Prevention threshold
UN6 0.10 99.90 bar High pressure - Prevention differential
UN9 0.10 99.90 bar Low pressure - Prevention threshold
UN10 0.10 99.90 bar Low pressure - Prevention differential
UN13 0 100 % Max. percentage limit in circuit 1 with capacity reduction
UN14 0 100 % Inverter scroll - Capacity reduction percentage override
UN15 0 100 % Max. percentage limit in circuit 2 with capacity reduction
UN17 0 999 min Capacity reduction activation time limit
UN18 0 999 min Time between two capacity reductions of the same circuit
Capacity reduction induced by low pressure probe
The controller offers the opportunity to override reduction capacity in the refrigerant circuit in order to keep the intake pres -
sure at higher values so as to prevent triggering alarms resulting from low pressure in the circuit.
The parameters involved are shown in the table.
Parameter Value UM Description
UN9 6.50 bar Low pressure - Prevention threshold
UN10 2.00 bar Low pressure - Prevention differential
UN13 50 % Max. percentage limit in circuit 1 with capacity reduction
UN14 42 % Inverter scroll - Capacity reduction percentage override
UN15 50 % Max. percentage limit in circuit 2 with capacity reduction
UN17 2 min Capacity reduction activation time limit
UN18 2 min Time between two capacity reductions of the same circuit
A graphical representation of capacity reduction due to low pressure is shown below.
t
UN9
Lp
C2
UN10
UN17
Off
On
UN17 UN18
Off
On
C1
Fig. 22 Capacity reduction due to low pressure
In addition to the parameters present in the table, the other abbreviations in the graph indicate:
- Lp = variation of low pressure value;
- C1 = status of compressor 1;
- C2 = status of compressor 2.
- t = time
3 Software functions