Daikin Navigator WWV - Evaporator Freeze Protection; Evaporator Pump Selection Logic; Condenser Pump Control States

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IOM 1264-4
WWW.DAIKINAPPLIED.COM
OPERATION
Evaporator Freeze Protection
To protect the evaporator from freezing, the evaporator pump will
start if the manual reset ow 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 ow 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 congurations:
• #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 rst. If the evaporator
state is Start for a time greater than the evaporator recirculate
timeout set point and there is no ow, then the primary pump will
shut o󰀨 and the standby pump will start. When the evaporator is
in the Run state, if ow is lost for more than half of the Evaporator
Flow Loss Delay set point value, the primary pump will shut
o󰀨 and the standby pump will start. Once the standby pump
is started, the ow loss alarm logic will apply if ow cannot be
established in the evaporator start state, or if ow 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.
Condenser Pump Control
For control of the condenser pumps, three condenser pump
control states are used:
1. O󰀨 - 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.
T1 – O󰀨 to Start - Transition should also occur if Freeze
Protection starts or RapidRestore is active. Requires all of the
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 ow seitch input is on
T3 – Run to O󰀨 - Requires all of the following to be true:
• Unit State = O󰀨 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 O󰀨 - Requires all of the following to be true:
• Unit State = O󰀨 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 ow switch input is o󰀨
START
RUN
3
5