5.11.2 DX based cooling (CclDx21y)
If ERC cannot maintain the supply air temperature setpoint, direct expansion
cooling coil can be activated and controlled as second cooling sequence.
Activation and operation of DX cooling differs from water based cooling so that
cooling valve request must first rise above 10 % (fix) before activation command to
DX unit is given. DX activation command is also removed at 5 % (fix) valve position
before the valve is completely closed. New activation command can be given
earliest after set off-time has elapsed.
Available parameters
Current value
BACnet object
R/RW
Note
Supply air temperature setpoint for cooling
SpTSuCcl
AVAL,224
R
°C
Cooling valve position
CclDxPos
AO,110 (A1)
AO,119 (A2)
AO,128 (A3)
AO,137 (A4)
AVAL,389 (POS9)
RW
%
Cooling DX status
CclDxCmd
BO,59 (Q1)
BO,74 (Q2)
BO,89 (Q3)
BVAL,250 (POS9)
RW
Cooling coil DX fault
CclDxFlt
BI,113 (X3)
BI,130 (X8)
BI,79 (D1)
BI,96 (D2)
R
Special settings
BACnet object
R/RW
Note
Cooling Kp
GainCclTSuCtrC
AVAL,225
RW
% / K
Cooling Tn
TnCclTSuCtrC
PINTVAL,112
RW
s
DX off time delay
CclDxTiOffMin
PINTVAL,116
RW
s
DX min run time
CclDxTiOnMin
PINTVAL,115
RW
s
Testing and debugging
BACnet object
R/RW
Note
Cooling coil device mode
CclDevMod
MVAL,158
1: Off
2: Control Mode
3: Full Open
Application functionalities
Cooling
5
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A6V10733786_en_c
