Daikin Magnitude Installation, Operation And Maintenance Manual page 44

to smooth the control and reduce fan cycling. See
38 and Figure 41.
Figure 40: TOWER Setpoint - SP2 - (III) VALVE STAGE
Cooling Tower
Fan Staging
(Up to 4 fans)
Tower
Control
Panel
MicroTech II
®
Controller
Condenser
Figure 41: (III) VALVE STAGE -
Valve Opening vs. Temperature
100
80
60
40
20
0
65 70
Temperature (°F)
4 Fan Stages
As shown in Figure 41, the default minimum and maximum
valve opening positions are 10% and 100%, respectively.
These minimum and maximum positions are adjustable
anywhere between 0% and 100%. Additional fans stage on
when the valve opening position reaches the maximum value
that was set.
(IV) VFD STAGE: In this mode, a VFD controls the first fan.
Up to three more fans are staged on and off and there is
no bypass valve. See
Figure 42: TOWER Setpoint - SP2 - (IV) VFD STAGE
Cooling Tower
Fan Staging
(Up to 4 fans)
Tower
Control
Panel
0-10 VDC
w/ Fan
Signal
VFD
MicroTech II
®
Controller
Condenser
IOM 1210-7 • MAGNITUDE
Bypass Line
0-10 VDC Signal
75 80 85
1 Fan Stage
Figure 42 and Figure 43.
MODEL WMC CHILLERS
®
Figure Figure 43: (IV) VFD STAGE - VFD Speed vs. Temperature
100
80
60
40
20
0
Bypass
65
Valve
As shown in Figure
VFD speeds are 20% and 100%, respectively. These minimum
and maximum values are adjustable anywhere between 0%
and 100%. Additional fans stage on when the VFD speed
reaches the maximum value that was set.
(V) VALVE SP / VFD STAGE: This control strategy is tower
fan control with a VFD and bypass valve control. See
Figure 44
Figure 44: TOWER Setpoint - SP2 - (V) VALVE SP /
Cooling Tower
Fan Staging
(Up to 4 fans)
90
0-10 VDC
Signal
MicroTech II
®
Controller
Condenser
Figure 45: (V) VALVE SP / VFD STAGE -
Percent vs. Temperature
100
80
60
40
20
0
60
% VFD Speed (4 Fan Stages)
% Valve Opening
42
70 75 80
Temperature (°F)
4 Fan Stages 1 Fan Stage
43, the default minimum and maximum
and Figure 45.
VFD STAGE
Tower
Control
Panel
w/ Fan
VFD
Bypass Line
0-10 VDC Signal
65 70 75 80
Temperature (°F)
% VFD Speed (1 Fan Stage)
www.DaikinApplied.com
o
peraTIon
85 90
Bypass
Valve
85 90