www.DaikinApplied.com 63 IOM 1322 • WATER-COOLED SCROLL COMPRESSOR
Low Ambient Lockout
This feature is only available on air cooled units
(WaterCooled=O).If the OAT drops below the low ambient
lockout set point, then all running circuits will do a normal stop.
Once the lockout has been triggered, no compressors will start
until the OAT rises to the lockout set point plus 5°F.
Unit State
The Unit will always be in one of three states. These states are
Off, Auto, and Pumpdown. Transitions between these states
are shown in the diagram on the following page.
T1: O to Auto
Unit Enable = True AND
No Unit Alarm AND
IF Unit Mode = Cir 1 Available OR Cir 2 Available
T2: Auto to Pumpdown
Keypad Enable = O OR
BAS Enable = O OR
Remote Switch = O OR
T3: Pumpdown to O
Unit Alarm OR
Unit Switch O OR
No Compressors Running
T4: Auto to O
Unit Alarm OR
Unit Switch O OR
No Compressors Running AND [Unit Mode = Ice AND Ice
Delay Active] OR
No Compressors Running AND [No Circuit Available]
Figure 36: Unit State Diagram
Evaporator Water Pump State Control (Evap State)
The state-transition diagram shown below controls operation of
the evaporator pump.
Figure 37: Evaporator Pump State Diagram
Pump Selection
The pump output used will be determined by the Evap
Pump Control set point. The setting allows the following
congurations:
Auto – The primary pump is the one with the least run hours,
the other is used as a backup.
backup.
backup.
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