Daikin UATYA-B, Operation Manual

Page: 67 / 126

67
Service manual Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
In normal operating conditions the signal controlling the external air and exhaust air dampers can range from the min.
setpoint stored in parameter “DA12” to the max. setpoint in parameter “DA13” (opening of the recirculated air damper is
complementary).
If the condensing pressure increases and reaches the setpoint stored in parameter “DA28”, the value of the damper ope
-
ning signal is limited.
Within differential “DA29” the signal is limited linearly between the min. and max. setpoint values stored in parameters
“DA36” and “DA37” respectively.
After limiting the damper opening value, the signal is fixed at the value set in parameter “DA37” for the entire differential
stored in parameter “DA40”, if the condensing pressure drops below the setpoint in parameter “DA28”.
The damper opening signal starts following the ongoing opening percentage again only after condensing pressure values
drop below the difference “DA28” – “DA40”.
3.14.2 Limitation based on evaporating pressure in cooling mode
When a refrigerant circuit in the unit is operating in cooling mode, the evaporating pressure may limit the damper control
signal.
The parameters concerned are shown in the table.
The values of the parameters are representative. In specific cases, different values can be set.
Parameter Value UM Description
DA12 30 % External air - FC / FH - Min opening
DA13 100 % External air - FC / FH - Max opening
DA30 12.00 bar
External air - Opening limitation - Summer oper. - Max evap. press. threshold for
activation
DA31 2.00 bar External air - Opening limitation - Summer oper. - Max evap. press. diff. for activation
DA38 0 % External air - Opening limitation - Min opening for evap. press.
DA39 60 % External air - Opening limitation - Max opening for evap. press.
DA41 2.00 bar External air - Opening limitation - Deactivation diff. for cond. press.
A graphical representation is shown below.
DA30
DA39
DA13
DA12
%
Pevap (bar)
DA38
DA31 DA41
Fig. 32 Damper command in free cooling mode
3 Software functions