Trane RTHD series Installation, Operation And Maintanance page 84

Operator Interface Controls
Table 24. Operating Modes
Chiller Modes
Heat Recovery Water Pump PreRun Time
2 min:sec
Heat Recovery Active
Normal To Heat Recovery Transition
Heat Recovery To Normal Transition
EXV Controlling Differential Pressure
Chilled Water Control
Running – Limited
Condenser Pressure Limit
Low Evaporator Refrigerant Temperature
Inhibit
Capacity Limited by Low Liquid Level
Current Limit
Phase Unbalance Limit
Low Discharge Superheat Limit
Oil Loss Avoidance
Note: Other normal running modes (see above) may also appear under this top level mode
Shutting Down
Local Stop
immediate Stop
Diagnostic Shutdown – Manual Reset
Diagnostic Shutdown – Auto Reset
Compressor Unloading
Starting is Inhibited by External Source
Start Inhibited by BAS
Evaporator Water Pump Off Delay min:sec
Service Override
Service Pumpdown
For heat recovery unit, may have below operation
modes:
1. Cooling
2. Cooling + Heat recovery
3. Heating
Conditions for entering heat recovery(below conditions
should both meet):
1. Chiller is at cooling mode
2. Heat recovery option enabled
3. Chiller is running
84
Description
In this mode, the chiller will wait for a period of time (the user can adjust) to meet the tem-
perature requirements of the heat recovery water circuit.
The heat recovery is running.
The unit is in the conversion process of refrigeration mode to heat recovery mode.
The unit is in the conversion process of heat recovery mode to refrigeration mode.
Liquid level control of the Electronic Expansion Valve has temporarily been suspended. The
EXV is being modulated to control for a minimum differential pressure. This control implies
low liquid levels and higher approach temperatures, but is necessary to provide minimum oil
flow for the compressor until the condenser water loop can warm up to approx 50F.
Unit is running in the Cooling Mode of operation and is attempting to control to the active
Chilled Water Setpoint. (Note this mode was not necessary prior to the introduction of Hot
Water Control)
The chiller, circuit, and compressor are currently running, but the operation of the
chiller/compressor is being actively limited by the controls. Further information is
provided by the sub-mode.* See the section below regarding criteria for annuncia-
tion of limit modes
The circuit is experiencing condenser pressures at or near the condenser limit setting. Com-
pressors on the circuit will be unloaded to prevent exceeding the limits.*
The circuit is experiencing saturated evaporator temperatures at or near the Low Refrigerant
Temperature Cutout setting. Compressors on the circuit will be unloaded to prevent tripping.
*
The circuit is experiencing low refrigerant liquid levels and the EXV is at or near full open.
The compressors on the circuit will be unloaded to prevent tripping.*
The compressor is running and its capacity is being limited by high currents. The current
limit setting is 100% RLA (to avoid overcurrent trips) or lower as set by the compressor's
"share" of the active current limit (demand limit) setting for the entire chiller.*
The compressor is running and its capacity is being limited by excessive phase current unbal-
ance.*
This is limit control that acts to prevent chiller shutdown when the discharge superheat ap-
proaches the limit setpoint by reducing the liquid level and unloading the slide valve.
This is limit control that acts to prevent chiller shutdown when the estimated refrigerant flow
approaches the calculated minimum flow by increasing the slide valve capacity and/or VFD
frequency
The chiller is still running but shutdown is imminent. The chiller is going through a
compressor run-unload. sequence. Shutdown is necessary due to one (or more) of
the following sub-modes:
Chiller is in the process of being stopped by TD7 Stop button command
Chiller is in the process of being stopped by TD7 Panic Stop command
Chiller is in the process of being stopped by a Latching Diagnostic shutdown – Manual Reset
is required to clear
Chiller is in the process of being stopped by a Diagnostic shutdown – Automatic clearing of
the diagnostic is possible if condition clears.
min:sec The compressor is in its "run – unload" state in which it is being continuously unloaded for
40 sec prior to shutdown.
Chiller is in the process of being stopped by the External Stop hardwired input
The Chiller is in the process of shutdown due to a command from the Building Automation
System (e.g. Tracer)
The Chiller is in a Service Override mode
The chiller, circuit, and compressor is running via a manual command to perform a Service
Pumpdown. Both evap and condenser water pumps are commanded to be running. The EXV
is being held wide open, but the manual liquid line service valve should be closed.
4. Customer water tank temperature <set point-margin
5. Heat recovery water flow detected
6. No diagnostic
7. Heat recovery ignore time expired
Condition for exiting heat recovery(below condition just
need meet any one):
1. Customer water tank temp>=set point + margin
2. Condenser pressure >170psig
3. Heat recovery option disabled
4. Chiller stop
5. Chiller has diagnostic
RTHD-SVX02H-EN