Daikin WGZ030DW, Operating And Maintenance Manual

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Primary/Standby Pump Staging
The pump designated as primary will start first. If the evaporator state is start for a time greater than the
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 flow proof
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
the flow is lost in the evaporator run state.
Auto Control
If auto pump control is selected, the primary/standby logic above is till 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.
Evaporator Water Flow Loss
The Evaporator Water Flow Loss logic allows the Unit to shutdown compressors on a loss of flow up to
two times every twenty-four hours before locking the unit out on a Evaporator Flow Loss Alarm.
•
If there are no compressors running when Evaporator Water Flow Loss is indicated the Unit Status
changes to Auto:Wait for flow. The evaporator water pump state changes to Start and no alarms are
indicated.
•
If an Evaporator Water Flow Loss occurs while a compressor is running all of the running
compressors will be shutdown. The alarm indicators are turned On and the Circuit Status for any
circuit with running compressors becomes Off: Ready, the Unit Status becomes Auto: Wait For Flow
and the evaporator water pump state changes to Start
•
When flow is reestablished the Unit Status becomes Auto: Recirculate while the Evaporator Flow
Recirculation Timer counts down. If there is continuous evaporator water flow while the Evaporator
Recirculation Timer counts down the Alarm indicator is turned off, and the unit resumes normal start
up procedures based on water temperature and cycle timers.
•
If second Evaporator Water Flow Loss occurs within twenty-four hours the process described above is
repeated.
•
If a third loss of flow is indicated in a twenty-four hour time frame the unit will shut down on an
Evaporator Water Flow Loss alarm and it will be locked out until this alarm is manually cleared.
•
The twenty-four hour timer that limits the auto restart is reset when the control clock rolls over 00:00
each night.
Condenser Fans – Air Cooled
Air-cooled condenser fan control is active only when the water cooled set point is set to off.
Fantrol
Fans 1, 3, 5, 7, 9, 11 are for circuit #1, and fans 2, 4, 6, 8, 10, 12 are for circuit 2. Fans 1 and 2 start with
the first compressor on the respective circuit when the ambient temperature is greater than 75°F. Below
75°F, these fans start when the condenser saturated temperature gets up to the condenser saturated
temperature target. The compressor must be running in order to run any fans. R22 and R407C units are
limited to 8 fans.
Fan Stages
There are 2, 3, 4, 5 or 6 fans available per circuit. On 8, 10, and 12 fan units, fans 5/7, 6/8, 9/11 and 10/12
are controlled by one contactor for each pair, using virtual stages to allow a difference of only one fan
between stages, See tables below:
4 and 6-Fan Remote Condenser
Stage Fans Operating on Circuit 1 Fans Operating on Circuit 2
1 Fan 1 Fan 2
2 Fans 1 & 3 Fans 2 & 4
3 Fans 1, 3, 5 Fans 2, 4, 6