Ice Machine Control - Trane CVHE Troubleshooting Manual

If the UCM has the capacity for some other feature to reset the cooling tower temperature, the
cooling tower temperature is reset to its minimum value or the cooling tower commanded to run
at full capacity.
ICE-BUILDING may be terminated by one of three means:
1 Opening the External Ice Contacts/Remote communicated input (Tracer), or satisfying an
evaporator entering water temperature setpoint, or surging for 15 minutes at full open IGV
2 In general, if there is an MAR diagnostic during either ICE-BUILDING or ICE BUILDING
COMPLETE and the diagnostic clears the chiller shall return to either ICE-BUILDING or ICE-
BUILDING COMPLETE, respectively
3 If the ice building complete mode is reached and the ice building complete mode is exited due
to a diagnostic or a system stop command, removing the diagnostic or returning the system to
the auto mode will cause the system to return to the ice building complete mode. The system
will leave ice building complete when the ice building command is released in any mode.
During ICE-BUILDING, any other action specified for Normal Cooling due to surge detection is
overridden. If surge is detected continuously for 15 minutes while in ICE-BUILDING and while the
IGVs are fully open, shutdown the chiller on a latching MAR diagnostic; the chiller is latched out
of ICE-BUILDING until the Ice-Building command is cycled; Normal Cooling is permitted. (Notice
in both ICE-BUILDING and NORMAL COOLING a surge diagnostic is a MMR diagnostic.,
however, if there was a surge diagnostic. when in ICE-BUILDING the diagnostic is automatically
cleared when the ice-building command is withdrawn.)
The UCM shall accept a non-volatile "Front Panel Ice Termination Setpoint" adjustable from 20 to
31°F (-6.7 to -0.5°C) in at least 1°F (0.1°C) increments. When the evaporator entering water
temperature drops below the ice termination setpoint the chiller will enter it's shutdown
sequence.
If ICE-BUILDING is terminated by either the External Ice contacts opening or the Remote
Communicated input (Tracer) while the compressor is running, as noted above, the compressor
will be unloaded at its maximum rate, however, the chiller will continue to operate at minimum
capacity for an adjustable 0 to 10 minutes; call this the "Ice-to-Normal Cooling Timer" (default
value to be 5 minutes). If during the Ice-to-Normal Cooling Time the LWT becomes greater than
the Normal Cooling Differential To Stop shutdown temperature, the chiller will be returned to
Normal LWT control and shutdown on the Normal Differential to Stop criteria. If the Normal
Cooling Differential to Stop shutdown temperature is not reached during the Ice-to-Normal
Cooling Time, the chiller enters its shutdown sequence; chiller restart will then be based on the
Normal Cooling Differential to Start criteria.
Ice Building will only be permitted when both the unit is in Auto and the last mode of operation
has been normal (non-ice building) AUTO (either running or not running). See the following table:
Unit Status
0 = Stop
1 = Auto
CVHE-SB-32A
or
or
Ext Ice Input Entr Evap
Temp
Compared to
Ice-ter Setpt
Chiller Mode
103