www.DaikinApplied.com 55 IOM 1322 • WATER-COOLED SCROLL COMPRESSOR
If active via trigger condition 1:
When the alarm occurs due to this trigger, it can auto reset
the rst two times each day, with the third occurrence being
manual reset.
For the auto-reset occurrences, the alarm will reset
automatically when the evaporator state is Run again. This
means the alarm stays active while the unit waits for ow, then
it goes through the recirculation process after ow is detected.
Once the recirculation is complete, the evaporator goes to the
Run state which will clear the alarm. After three occurrences,
the count of occurrences is reset and the cycle starts over if the
manual reset ow loss alarm is cleared.
If active via trigger condition 2:
If the ow loss alarm has occurred due to this trigger, it is
always a manual reset alarm.
Alarm description (as shown on screen): Condenser Flow
Loss
Trigger:
1. Condenser Pump State = Run AND Condenser Flow
Digital Input = No Flow for time > Cond Flow Proof Set
Point AND at least one compressor running.
2. Condenser Pump State = Start for time greater than
Recirc Timeout Set Point AND all pumps have been tried
AND Condenser Flow Digital Input = No Flow.
Action Taken: Rapid stop all circuits.
Reset:This alarm can be cleared at anytime manually via the
keypad or via the BAS clear alarm signal.
If active via trigger condition 1:
When the alarm occurs due to this trigger, it can auto reset
the rst two times each day, with the third occurrence being
manual reset.
For the auto-reset occurrences, the alarm will reset
automatically when the condenser pump state is Run again.
This means the alarm stays active while the unit waits for
ow, then it goes through the recirculation process after ow
is detected. Once the recirculation is complete, the condenser
pump goes to the Run state which will clear the alarm. After
three occurrences, the count of occurrences is reset and the
cycle starts over if the manual reset ow loss alarm is cleared.
If active via trigger condition 2:
If the ow loss alarm has occurred due to this trigger, it is
always a manual reset alarm.
Low Evaporator Pressure
Alarm description (as shown on screen):
Evap Press Low Cir N
Trigger: [Circuit State = Run AND Freezestat trip AND Low
OAT Start not active]
OR Evaporator Press < Absolute Low Pressure Limit AND
Circuit State = Run
The absolute low pressure limit is 5 psi with R134a refrigerants
and 20 psi with R410A refrigerant.
Freezestat logic allows the circuit to run for varying times at
low pressures. The lower the pressure, the shorter the time the
compressor can run. This time is calculated as follows:
Freeze error = Low Evaporator Pressure Unload – Evaporator
Pressure
Freeze time =
[60 – 2.7 x freeze error] with R134a refrigerant, limited to a
range of 20-60 seconds
[60 – freeze error] with R410A refrigerant, limited to a range
of 20-60 seconds
When the evaporator pressure goes below the Low Evaporator
Pressure Unload set point, a timer starts. If this timer exceeds
the freeze time, then a ‘Evap Press Low Cir N’ alarm trip
occurs. If the evaporator pressure rises to the unload set point
or higher, and the freeze time has not been exceeded, the
timer will reset.
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad if
the evaporator pressure is above the absolute
low-pressure limit.
High Condenser Pressure
Alarm description (as shown on screen):
Cond Press High Cir N
Trigger: Condenser Pressure > High Condenser Pressure Set
Point
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad.
Mechanical High Pressure/Motor Protect
Alarm description (as shown on screen):
MHP or Motor Prot N
Trigger: MHP/MP input is low and over 150 seconds lapsed
since controller boot-up
Action Taken: Rapid stop circuit
Reset: This alarm can be cleared manually via the keypad if
the MHP/MP input is high.
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