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RTAC-SVX01F-EN 97
Controls Interface
Start Inhibited by BAS The chiller is inhibited from starting (and running) by
command from a Building Automation System via the
digital communication link (com 3 or com 5).
Waiting for BAS Communications This is a transient mode - 15-min. max, and is only
possible if the chiller is in the Auto - Remote command
mode. After a power up reset, it is necessary to wait for
valid communication from a Building Automation System
(Tracer) to know whether to run or stay inhibited. Either
valid communication will be received from the Building
Automation System (e.g. Tracer), or a communication
diagnostic ultimately will result. In the latter case the
chiller will revert to Local control.
Ice Building to Normal Transition The chiller is inhibited from running for a brief period of
time if it is commanded from active ice building mode
into normal cooling mode via the ice building hardwired
input or Tracer. This allows time for the external system
load to "switchover" from an ice bank to the chilled water
loop, and provides for a controlled pull down of the
loop's warmer temperature. This mode is not seen if the
ice making is automatically terminated on return brine
temperature per the mode below.
Ice Building is Complete The chiller is inhibited from running as the Ice Building
process has been normally terminated on the return brine
temperature. The chiller will not start unless the ice
building command (hardwired input or Building
Automation System command) is removed or cycled.
Auto The chiller is not currently running but can be expected to
start at any moment given that the proper conditions and
interlocks are satisfied. Further information is provided
by the sub-mode:
Waiting For Evap Water Flow The chiller will wait up to 4 minutes in this mode for
evaporator water flow to be established per the flow
switch hardwired input.
Waiting for Need to Cool The chiller will wait indefinitely in this mode, for an
evaporator leaving water temperature higher than the
Chilled Water Setpoint plus the Differential to Start.
Starting The chiller is going through the necessary steps to allow
the lead circuit and lead compressor to start.
No Sub Modes
Running At least one circuit and one compressor on the chiller are
currently running. Further information is provided by the
sub-mode:
Table 25 Chiller Modes
Chiller Modes Description
Top Level Mode
Sub-modes