Daikin WMC Installation, Operation And Maintenance Manual page 34

Explanation of Tower Control Settings
There are five possible tower control strategies: (I) NONE,
(II) VALVE SP, (III) VALVE STAGE, (IV) VFD STAGE, and
(V) VALVE SP / VFD STAGE. These control strategies are
selected from the TOWER Setpoint Screen (see
on page 31) using Setpoint 2. (In the following pages, "SP"
means "Setpoint.") An explanation of each control strategy
follows this paragraph. Along with each explanation is a
diagram and graph to help illustrate the control strategy. Note
that these graphs illustrate the default conditions for each
strategy. See "Setting Tower Control Using the OITS Panel"
on page 34 for details on how to set these tower control
strategies.
(I) NONE: This control strategy is tower fan staging only.
This is not a recommended strategy. In this mode the
tower fan staging (up to four stages) is controlled by
either the condenser Entering Water Temperature (EWT)
or LIFT pressure (difference between the condenser and
evaporator pressure). Tower bypass or fan speed are not
controlled. See Figure 32
Figure 32: TOWER Setpoint - SP2 - (I) NONE
Cooling Tower
Fan Staging
(Up to 4 fans)
Tower
Control
Panel
MicroTech II
®
Controller
Condenser
Figure 33: (I) NONE - Temperature vs. Fan Stages
95
90
85
80
75
70
65
0 1
(II) VALVE SP: This control strategy is tower staging (up to
four stages) with a low-limit controlled bypass valve. The
tower fans are controlled as in (I), plus a tower bypass
valve is controlled to provide a minimum condenser EWT.
There is no interconnection between the fan control and
the valve control. See
IOM 1210-1 • MAGNITUDE
Figure 31
and Figure 33.
2 3 4
Fan Stages
Figure 34 and Figure 35.
MODEL WMC CHILLERS
®
Figure 34: TOWER Setpoint - SP2 - (II) VALVE SP
Cooling Tower
Fan Staging
(Up to 4 fans)
MicroTech II
®
Controller
Condenser
Figure 35: (II) VALVE SP - Valve Opening vs. Temperature
100
80
60
40
20
0
60 65
As shown in Figure
valve opens completely is 65°F. This temperature is the Valve
SP and is adjustable.
(III) VALVE STAGE: This control strategy is tower staging (up
to four stages) with a stage-controlled bypass valve. In
this mode, the bypass valve controls between fan stages
to smooth the control and reduce fan cycling. See
34 and Figure
Figure 36: TOWER Setpoint - SP2 - (III) VALVE STAGE
Cooling Tower
Fan Staging
(Up to 4 fans)
MicroTech II
®
5
Controller
Condenser
32
Tower
Control
Panel
Bypass Line
0-10 VDC Signal
70 75 80
Temperature (°F)
35, the default temperature at which the
37.
Tower
Control
Panel
Bypass Line
0-10 VDC Signal
www.DaikinApplied.com
o
peraTIon
Bypass
Valve
85 90
Figure
Bypass
Valve