Carrier 19XL - Manual (Page 123)

compressor is running in a lightly loaded condition. This cycling of the chiller is normal and is
known as recycle. A recycle shutdown is initiated when any of the following conditions are true:
• when in LCW control, the LEAVING CHILLED WATER temperature is more than 5° F
(3° C) below the control point, and the CONTROL POINT has not increased in the
last 5 minutes
• when ECW CONTROL OPTION is enabled, the ENTERING CHILLED WATER tem-
perature is more than 5° F (3° C) below the CONTROL POINT , and the CONTROL
POINT has not increased in the last 5 minutes
• when the LEAVING CHILLED WATER temperature is within 3° F (2° C) of the BRINE
REFRIG TRIPPOINT.
When the machine is in RECYCLE mode, the chilled water pump relay remains energized so
that the chilled water temperature can be monitored for increasing load. The recycle control
uses RECYCLE RESTART DELTA T to check when the compressor should be restarted. This
is an operator-configured function which defaults to 5° F (3° C). This value is viewed/modified
on the Service1 table. The compressor will restart when:
• in LCW CONTROL the LEAVING CHILLED WATER temperature is greater than the
CONTROL POINT plus the RECYCLE RESTART DELTA T ; or
• in ECW CONTROL, the ENTERING CHILLED WATER temperature is greater than
the CONTROL POINT plus the RECYCLE RESTART DELTA T
Once these conditions are met, the compressor shall initiate a start-up, with a normal start-up
sequence.
An alert condition may be generated if 5 or more RECYCLE STARTUPs occur in less than 4