IOM 1264-1 • NAVIGATOR
®
MODEL WWV CHILLERS
28 www.DaikinApplied.com
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Condenser Freeze Protection
To protect the condenser from freezing, the condenser pump
will start if the manual reset flow loss alarm is not active and
either of the following are true:
• LWT is equal to or less than the Cond Freeze set point for
at least three seconds AND LWT sensor fault isn’t active
• EWT is equal to or less than the Cond Freeze set point
minus 0.6°C for at least three seconds AND EWT sensor
fault isn’t active
Freeze protection will end when manual reset flow loss alarm
is active or all of the following are true:
• LWT is at least 1.11°C (2°F) above the Cond Freeze set
point or LWT sensor fault is active
• EWT is at least 1.11°C (2°F) above the Cond Freeze set
point or EWT sensor fault is active
• Pump has been running for at least 15 minutes
Condenser Pump Selection
Condenser pump selection, staging, auto control, starts and
run hours function in the same way as for the evaporator
section beginning on
page 27.
Cooling Tower Control
WWV cooling tower control includes the capability to control 1
or 2 fan stages, a bypass valve, and a fan VFD.
Cooling Tower Fan Staging
Tower fan staging is enabled when the Tower Control set point
is set to a CP (controlled parameter) of either Condenser EWT
or Condenser LWT based on the Tower Control set point. A
stage timer should start when the condenser pump starts or
when the fan stage is changed.
The first stage should turn on when the following conditions are
met:
• Stage timer > Tower Fan Stage On Delay set point
• CP > Stage 1 On Temperature set point
• Bypass valve position > Stage On Position/Speed set
point (if Valve/VFD Control Configuration = Valve Stage)
• VFD Speed > Stage On Position/Speed set point (if
Valve/VFD Control Configuration = VFD Stage or Valve
SP/VFD Stage)
The second fan stage can turn on when the following
conditions are met:
• Number of Tower Fan Stages = 2
• Stage timer > Stage On Delay set point
• CP > Stage 2 On Temperature set point
• Bypass valve position > Stage On Position/Speed set
point (if Valve/VFD Control Configuration = Valve Stage)
• VFD Speed > Stage On Position/Speed set point (if
Valve/VFD Control Configuration = VFD Stage or Valve
SP/VFD Stage)
The second fan stage should turn off when the following
conditions are met:
• Stage timer > Tower Fan Stage Off Delay set point
• CP < Stage 2 On Temperature set point – Stage Off
Differential set point
• Bypass valve position < Stage Off Position/Speed set
point (if Valve/VFD Control Configuration = Valve Stage)
• VFD Speed < Stage Off Position/Speed set point (if
Valve/VFD Control Configuration = VFD Stage OR Valve
SP/VFD Stage)
The first fan stage should turn off when the following conditions
are met:
• Stage timer > Tower Fan Stage Off Delay set point
• CP < Stage 1 On Temperature set point – Stage Off
Differential set point
• Bypass valve position < Stage Off Position/Speed set
point (if Valve/VFD Control Configuration = Valve Stage)
• VFD Speed < Stage Off Position/Speed set point (if
Valve/VFD Control Configuration = VFD Stage OR Valve
SP/VFD Stage)
The fan stage should also be set to 0 when condenser pump
state is not Run.
Cooling Tower Bypass Valve
When the Valve/VFD Control Configuration set point is set
to None or VFD Stage, bypass valve control should not be
operational and the position should always be set to 0%.
If the Valve/VFD Control Configuration set point is set to Valve
Set Point or Valve SP/VFD Stage the bypass valve should be
controlled in Valve Set Point Mode.
If the Valve/VFD Control Configuration set point is set to Valve
Stage the bypass valve should be controlled in Valve Stage
Mode.
For both valve control modes, when active a valve position
is calculated and limited to a range from the Minimum Valve
Position set point to the Maximum Valve Position set point.
As the calculated position varies from 0 to 100%, the voltage
signal for the Bypass Valve Position output should vary based
on the Valve Type set point:
• If ‘NC to tower’ then 0 to 100% = 0 to 10 VDC
• If ‘NO to tower’ then 0 to 100% = 10 to 0 VDC
Valve Set Point Mode
This mode is enabled when the Valve/VFD Control set point
is set to Valve Setpoint or Valve SP/VFD Stage. The valve
position should be 0% when the condenser state is not Run.
When the condenser state becomes Run, the valve position
will be controlled to a position limited to a range from the
Minimum Valve Position set point to the Maximum Valve
Position set point.
In this mode the valve position is calculated by a PID loop to
control the condenser EWT or LWT (as selected by the Tower
Control set point) to the Valve/VFD Set Point.
Summary of Contents for Navigator WWV
Page 4: ......
