Daikin MicroTech III, Operating Manual

Page: 11 / 77

11/77 Operation Manual D
–EOMWC00A07-16_02EN
5 SEQUENCE OF OPERATION
Figure 5, Unit Sequence of Operation (see Figure 9 for circuit sequence of operation)
Is unit enabled?
Is flow present?
Evaporator pump output on
Wait for chilled water loop to
recirculate.
Yes
Yes
No
Unit power up
Unit in Off state
No
The chiller may be disabled via the unit switch, the remote switch, the keypad
enable setting, or the BAS network. In addition, the chiller will be disabled if all
circuits are disabled, or if there is a unit alarm. If the chiller is disabled, the unit
status display will reflect this and also show why it is disabled.
If the unit switch is off, the unit status will be Off:Unit Switch . If the chiller is
disabled due to network command, the unit status will be Off:BAS Disable . When
the remote switch is open, the unit status will be Off:Remote Switch . When a unit
alarm is active, the unit status will be Off:Unit Alarm . In cases where no circuits
are enabled, the unit status will be Off:All Cir Disabled . If the unit is disabled via
the Chiller Enable set point, the unit status will be Off:Keypad Disable .
If the chiller is enabled, then the unit will be in the Auto state and the evaporator
water pump output will be activated.
After establishing flow, the chiller will wait some time to allow the chilled water loop
to recirculate for an accurate reading of the leaving water temperature. The unit
status during this time is
Auto:Evap Recirc .
The chiller will then wait for the flow switch to close, during which time the unit
status will be
Auto:Wait for flow .
Is low ambient lockout
active?
Yes
No
Low ambient lockout will prevent the chiller from starting even if it is otherwise
enabled. When this lockout is active, the unit status will be
Off:Low OAT Lock .
Is there enough load to
start chiller?
No
Keep pump output on while
chiller is enabled and either
running or ready to run.
The chiller is now ready to start if enough load is present. If the LWT is not higher
than the Active Setpoint plus the Start Up Delta T, the unit status will be
Auto:Wait
for load .
If the LWT is higher than the Active Setpoint plus the Start Up Delta T, the unit
status will be
Auto . A circuit can start at this time.
Yes
AWS Chiller Sequence of Operation in Cool Mode