Daikin Navigator WWV Installation, Operation And Maintenance Manual page 27

Evaporator Freeze Protection
To protect the evaporator from freezing, the evaporator pump
will start if the manual reset flow loss alarm is not active and
either of the following are true:
• LWT equal to or less than the Evap Freeze set point for at
least three seconds AND LWT sensor fault isn't active
• EWT equal to or less than the Evap Freeze set point 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 2°F (1.11°C) above the Evap Freeze set
point or LWT sensor fault is active
• EWT is at least 2°F (1.11°C) above the Evap Freeze set
point or EWT sensor fault is active
• Pump has been running for at least 15 minutes
Evaporator Pump Selection
The pump output used when evaporator state is Run will be
determined by Evap Pump Control set point. This setting
allows the following configurations:
• #1 only – Pump 1 will always be used
• #2 only – Pump 2 will always be used
• Auto – The primary pump is the one with the least run
hours, the other is used as a backup
• #1 Primary – Pump 1 is used normally, with pump 2 as a
backup
• #2 Primary – Pump 2 is used normally, with pump 1 as a
backup
Primary/Standby Pump Staging
The pump designated as primary will start first. If the
evaporator state is Start for a time greater than the evaporator
recirculate timeout set point and there is no flow, then the
primary pump will shut off and the standby pump will start.
When the evaporator is in the Run state, if flow is lost for more
than half of the Evaporator Flow Loss Delay set point value,
the primary pump will shut off and the standby pump will start.
Once the standby pump is started, the flow loss alarm logic will
apply if flow cannot be established in the evaporator start state,
or if flow is lost in the evaporator Run state.
Auto Control
If auto pump control is selected, the primary/standby logic
above is still used. When the evaporator is not in the Run state,
the run hours of the pumps will be compared. The pump with
the least hours will be designated as the primary at this time.
Counters for both starts and run hours should be maintained
for each pump. These should be displayed and should be
changeable.
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Condenser Pump Control
For control of the condenser pumps, three condenser pump
control states are used:
1. Off - No pump on.
2. Start – Pump is on, water loop is being recirculated.
3. Run – Pump is on, water loop has been recirculated and
circuits can start if needed.
RUN
T1 – Off to Start - Transition should also occur if Freeze
Protection starts or RapidRestore
following
• Evap State = Run
• Unit State = Auto
• Evap LWT Error > Start Delta T
T2 – Start to Run - Requires the following to be true for time
longer than condenser recurculate time set point:
• Cond State = Start
• Condenser flow seitch input is on
T3 – Run to Off - Requires all of the following to be true:
• Unit State = Off or Evap LWT Error < Start Delta T -
0.556°C
• Freeze Protection is not active
• RapidRestore is not active
®
• Compressor is not running
T4 – Start to Off - Requires all of the followingto be true:
• Unit State = Off or Evap LWT Error < Start Delta T -
0.556°C
• Freeze Protection is not active
• RapidRestore
® is not active
• Compressor is not running
T5 – Run to Start - Requires the following to be true for longer
than the Evaporator Flow Loss Delay set point:
• Cond State = Run
• Condenser flow switch input is off.
27 IOM 1264-1 • NAVIGATOR
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START
5
is active. Requires all of the
®
MODEL WWV CHILLERS
®