Daikin UATYA-B, Operation Manual

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Service manual Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
In addition to the parameters present in the table, the other abbreviations in the graph indicate:
- Hp = variation of high pressure value
- C1 = status of compressor 1;
- C2 = status of compressor 2.
- t = time
When the delivery pressure value measured is higher than the setpoint in parameter “UN5”, the controller overrides capa -
city reduction in the corresponding refrigerant circuit.
The capacity reduction override depends on the type and number of compressors featured in the circuit.
If only one compressor is fitted in the circuit and it is inverter controlled, capacity is reduced by the setpoint value stored in
parameter “UN14”. The value of parameter “UN13” in this case must be set to “100”.
If two compressors are fitted in the circuit and they are on-off type, capacity is reduced by the setpoint value stored in para
-
meter “UN13”. The correct value to set in parameter “UN13” to switch off one of the two compressors is “50”.
If the circuit is fitted with one inverter-controlled and one on-off compressor and capacity needs to be reduced in the inver
-
ter compressor, the value in parameter “UN13” must be set to “100” and the value in parameter “UN14” must be set at the
percentage value at which the inverter compressor is required to reduce its capacity. If capacity reduction is required to
switch off the on-off compressor and to bring the inverter compressor to the speed setpoint recorded in parameter “UN14”,
the value in parameter “UN13” must be set to “50” and the value in parameter “UN14” must be set at the percentage value
at which the inverter compressor is required to reduce its capacity.
If the unit consists of two refrigerant circuits, the first circuit behaves as described above.
The second refrigerant circuit always features two on-off compressors and capacity is reduced by the setpoint value stored
in parameter “UN15”. The correct value to set in parameter “UN15” to switch off one of the two compressors is “50”.
The capacity reduction override in circuits featuring one ON/OFF compressor only is not managed.
The capacity reduction override is stopped when the delivery pressure is lower than the setpoint value in parameter “UN5”,
minus the value in parameter “UN6”, or after the time setpoint stored in parameter “UN17” has elapsed.
If the capacity reduction override is stopped after the time set in parameter “UN17”, but the condition persists for the time
set in parameter “UN18”, the override is restored.
3 Software functions