IOM 1274-3 • CENTRIFUGAL WATER CHILLERS 50 www.DaikinApplied.com
Operation
Table 16: Tower Setpoint Settings
Description
Default
Range
PW
Comments
Valve Position (Bypass)
100%
Valve Control Slope Gain
1
0 to 99
T
Control gain for temperature (or lift) slope
Valve Control Error Gain
20
0 to 99
T
Control gain for temperature (or lift) error
Valve Control Range (Max)
100%
0 to 100%
T
Maximum valve position, overrides all other settings
Valve Control Range (Min)
10%
0 to 100%
T
Minimum valve position, overrides all other settings
Temp–Max. Start Position
90 °F
0 to 100 °F
T
Condenser EWT at which initial valve position is set to max start position
Maximum Start Position
100%
0 to 100%
T
Initial valve position when condenser EWT is at or above Temp-Max Start Position
Temp – Min. Start Position
60 °F
0 to 100 °F
T
Condenser EWT at which initial valve position is set to setpoint Stage Up @
Minimum Start Position
10%
0 to 100%
T
Minimum position of valve when condenser EWT is at or below setpoint Stage
Down
Valve Deadband (Lift)
1.0 psi
0 to 20.0 psi
T
Sets control deadband, Cooling Tower Control =Lift
Valve Deadband (Temp)
1.0 °F
0 to 10.0 °F
T
Sets control deadband, Cooling Tower Control =Temp
Valve Target (Lift)
30 psi
1 to 100 psi
T
Target for lift pressure (Cooling Tower Control = Lift), Works with Fan Stage Down
Time
Valve Target (Temp)
65 °F
40 to 120 °F
T
Target for condenser EWT (Cooling Tower Control = Temp),
Works with Fan Stage Up Time
VFD Stage Down @
20%
0 to 100%
T
Valve position below which the fans can stage down
(Tower Valve/Fan VFD Strategy = Valve Stage)
VFD speed below which the fans can stage down
(Tower Valve/Fan VFD Strategy = VFD stage or valve SP/VFD stage)
VFD Stage Up @
80%
0 to 100%
T
Valve position above which the fans can stage up
(Tower Valve/Fan VFD Strategy = Valve Stage)
VFD speed above which the fans can stage up
(Tower Valve/Fan VFD Strategy = VFD or valve SP/VFD stage)
Cooling Tower Control
None
None, Temperature, Lift
T
None: No tower control
Temperature: Fan and valve controlled by condenser EWT
Lift: Controlled by lift pressure
Tower Valve/Fan VFD
Strategy
None
None, Valve SP, Valve
Stage, VFD Stage,
Valve SP/VFD Stage
T
None: No tower valve or VFD
Valve Setpoint: Valve controls to Valve Target and Valve Deadband
Valve Stage: Valve controls between fan stages
VFD Stage: 1st fan is VFD controlled, no valve
Valve SP/VFD Stage: Both valve and VFD
Tower Valve Type
NC (To Tower) NC, NO
T
Normally closed or normally open to tower
Cooling Tower Stages
2
1 to 4
T
Number of fan stages used
Fan Stage Up Time
2 min
1 to 60 min
T
Time delay between stage up/down event and next stage up
Fan Stage Down Time
5 min
1 to 60 min
T
Time delay between stage up/down event and next stage down
Stage #4 On (Lift)
65 psi
10 to 130 psi
T
Lift pressure for fan stage #4 on
Stage #3 On (Lift)
55 psi
10 to 130 psi
T
Lift pressure for fan stage #3 on
Stage #2 On (Lift)
45 psi
10 to 130 psi
T
Lift pressure for fan stage #2 on
Stage #1 On (Lift)
35 psi
10 to 130 psi
T
Lift pressure for fan stage #1 on
Stage Differential (Lift)
6.0 psi
1.0 to 20.0 psi
T
Fan staging deadband with Cooling Tower Control=Lift
Stage #4 On (Temp)
85 °F
40 to 120 °F
T
Temperature for fan stage #4 on
Stage #3 On (Temp)
80 °F
40 to 120 °F
T
Temperature for fan stage #3 on
Stage #2 On (Temp)
75 °F
40 to 120 °F
T
Temperature for fan stage #2 on
Stage #1 On (Temp)
70 °F
40 to 120 °F
T
Temperature for fan stage #1 on
Stage Differential (Temp)
3.0 °F
1.0 to 10.0 °F
T
Fan staging deadband with Cooling Tower Control=Temp
