Operator Interface Controls
RTHD-SVX02H-EN 83
Table 24. Operating Modes
Chiller Modes Description
MP Resetting
Stopped The chiller is not running and cannot run without intervention. Further information
is provided by the sub-mode:
Local Stop Chiller is stopped by TD7 Stop button command– cannot be remotely overridden.
immediate Stop Chiller is stopped by the TD7 Panic Stop (by pressing Stop button twice in succession) – pre-
vious shutdown was manually commanded to shutdown immediately without a run-unload or
pumpdown cycle - cannot be remotely overridden.
Diagnostic Shutdown – Manual Reset The chiller is stopped by a diagnostic that requires manual intervention to reset.
Run Inhibit The chiller is currently being inhibited from starting (and running*), but may be
allowed to start if the inhibiting or diagnostic condition is cleared. Further infor-
mation is provided by the sub-mode:
Diagnostic Shutdown – Auto Reset The entire chiller is stopped by a diagnostic that may automatically clear.
Starting is Inhibited by External Source The chiller is inhibited from starting (and running) by the “external stop” hardwired input.
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 4 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 communi-
cation from a Building Automation System (Tracer) to know whether to run or stay inhibit-
ed. 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.
Power Up Delay Inhibit min:sec The compressor is currently being inhibited from starting as part of the power up start delay
(or staggered start) feature. This feature is intended to prevent multiple chillers from all
starting simultaneously if power is restored to all chillers simultaneously.
Low Differential Refrigerant Pressure Cool-
Down Timemin:sec
See Oil Flow Protection (Spec Page 78)
Auto The chiller is not currently running but can be expected to start at any moment
given that the proper conditions and interlocks are satised. Further information is
provided by the sub-mode:
Waiting For Evap Water Flow The chiller will wait up to 20 minutes in this mode for evaporator water ow to be established
per the ow switch hardwired input.
Waiting for A Need to Cool The chiller will wait indenitely in this mode, for an evaporator leaving water temperature
higher than the Chilled Water Setpoint plus the Differential to Start.
Waiting to Start The chiller is not currently running and there is a call for cooling but start is de-
layed by certain interlocks or proofs. Further information is provided by the sub-
mode:
Waiting For Cond Water Flow The chiller will wait up to 20 minutes in this mode for condenser water ow to be established
per the ow switch hardwired input.
Start Inhibited Waiting for Oil The chiller will wait up to 2 minutes in this mode for oil level to appear in the oil tank.
Condenser Water Pump Pre-Run
Timemin:sec
The chiller will wait up to 30 minutes (user adjustable) in this mode for to allow the condens-
er water loop to equalize in temperature
Restart Inhibit min:sec The compressor is currently unable to start due to its restart inhibit timer. A given com-
pressor is not allowed to start until 5 minutes (adj) has expired since its last start, once a
number of “free starts” have been used up.
Waiting For EXV Preposition The Chiller will wait for the time it takes the EXV to get to its commanded pre-position prior
to starting the compressor. This is typically a relatively short delay and no countdown timer
is necessary (less than 15 seconds)
Minimum Condenser Watermin:sec Only possible when Condenser Head Pressure Control option is enabled, this wait may be
necessary due to the Head Pressure control device’s stroke time.
Condenser Water Regulating Control
min:sec
Only possible when Condenser Head Pressure Control option is enabled, this wait may be
necessary due to the Head Pressure control device’s stroke time
Running The chiller, circuit, and compressor are currently running. Further information is
provided by the sub-mode:
High Discharge Temp Limit The compressor is running and is being forced loaded to its step load point, without regard
to the leaving water temperature control, to prevent tripping on high compressor discharge
temperature.
Base Loaded Chiller is running in “Base Load” operation where the capacity of the chiller is controlled to
maintain a given current per an adjustable set point. The chiller is forced to run without re-
gard to the chilled water temperatures and the differential to start and stop
Capacity Control Softloading The chiller is running, but loading is inuenced by a gradual ‘pulldown” lter on the chilled
water temperature setpoint The settling time of this lter is user adjustable as part of the
softload control feature.
Current Control Softloading The chiller is running, but loading is inuenced by a gradual lter on the current limit set-
point The starting current and the settling time of this lter is user adjustable as part of the
softload control feature.
Waiting For Heat Recovery Water Flow In this mode, the unit will wait for the establishment of heat recovery ow and the input of
the hardware interface of the ow switch.
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