7.6 Unit Status
The displayed unit status is determined by the conditions in the following table:
Unit State = Off, Unit Mode = Ice, and Ice Delay = Active
Unit State = Off and all compressors unavailable
Unit State = Off and Unit Alarm active
Unit State = Off and Unit Enable Set Point = Disable
Unit State = Off and Remote Switch is open
Unit State = Off, Control Source = Network, and BAS Enable = false
Unit State = Off and Unit Switch = Disable
Unit State = Off and Unit Mode = Test
Unit State = Auto and Noise Reduction is active
Unit State = Auto, no circuits running, and LWT is less than the active
set point + startup delta
Unit State = Auto and Evaporator State = Start
Unit State = Auto, Evaporator State = Start, and Flow Switch is open
Unit State = Auto, max pulldown rate has been met or exceeded
Unit State = Auto, unit capacity limit has been met or exceeded
Unit State = Auto, unit current limit has been met or exceeded
Off:Config Changed, Reboot
Unit State = Off and Unit Enable Set Point = Disable
Unit State = Off and Unit Enable Set Point = Disable
7.7 Ice Mode Start Delay
An adjustable start-to-start ice delay timer will limit the frequency with which the chiller may start in Ice mode. The timer
starts when the first compressor starts while the unit is in ice mode. While this timer is active, the chiller cannot restart in
Ice mode. The time delay is user adjustable.
The ice delay timer may be manually cleared to force a restart in ice mode. A set point specifically for clearing the ice mode
delay is available. In addition, cycling the power to the controller will clear the ice delay timer.
7.8 Evaporator Pump Control
Three evaporator pump control states for control of the evaporator pumps:
• Off - No pump on.
• Start – Pump is on, water loop is being recirculated.
• Run – Pump is on, water loop has been recirculated.
The control state is Off when all of the following are true:
• Unit state is Off
• LWT is higher than the Evap Freeze set point or LWT sensor fault is active
• EWT is higher than the Evap Freeze set point or EWT sensor fault is active
The control state is Start when any of the following are true:
• The unit state is auto
• LWT is less than the Evap Freeze set point minus 0.6 °C and LWT sensor fault isn’t active
• EWT is less than the Evap Freeze set point minus 0.6 °C and EWT sensor fault isn’t active
The control state is Run when the flow switch input has been closed for a time greater than the Evaporator Recirculate set
point.