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Steam-turbine-driven centrifugal chiller (via SC-EQ card) · BACnet points list

York YST Steam Turbine Chiller (SC-EQ) BACnet points list

Updated 28 October 2026

Short answer

YORK by Johnson Controls YST chillers drive a centrifugal compressor with a steam turbine. The SC-EQ communication card exposes them on BACnet MS/TP (or Modbus RTU / N2). Remote commands are run/stop, leaving chilled water setpoint and a turbine horsepower limit; the rest is read-only: chiller and turbine temperatures, pressures, speed, steam flow, bearing and hotwell values, contact states, and multistate status and fault codes.

This page lists 74 BACnet objects for the York YST Steam Turbine Chiller (SC-EQ) — 4 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from York’s own free documentation, linked below.

Manufacturer
York
Model
YST Steam Turbine Chiller (SC-EQ)
Equipment
Steam-turbine-driven centrifugal chiller (via SC-EQ card)
Equipment type
Chillers
BACnet objects
74 (4 writable)
Transport
BACnet MS/TP
Firmware
SC-EQ software 4.2.0.20
Default device instance
5000 + MAC address
Also known as
YORK YST, YST chiller, steam turbine drive chiller, SC-EQ, SE-SCC1001-1
Source document
YST SC-EQ BAS Points List · rev. Rev 1.2, 2021-12-08
Download CSV 74 rows Download EDE B.I.G.-EU JSON Manufacturer PDF ↗ Download Easy BACnet Mobile App Google Play

BMS integration notes: York YST Steam Turbine Chiller (SC-EQ)

Integration in brief

Run and stop it with BV 1, write the leaving chilled water setpoint (AV 1) and the turbine horsepower limit (AV 2). Read MV 1 and MV 6 for chiller and turbine state, the leaving water temperature and PRV position, and MV 2/MV 3 for safety and cycling shutdowns.

Minimum points to map

The short list most integrators start with — enough to run the unit from a BMS. Map more as the job needs.

ObjectNameWhyAccess
BV 1REM RUN STOP CMDRemote run/stop (1 = run)Command
AV 1REM LEAVING CHW TEMP SPRemote leaving chilled water setpointCommand
AV 2TURBINE HP LIMIT SPTurbine horsepower limit, % (demand limit)Command
MV 1UNIT OPERATION CODEOperating state (stopped, starting, running)Read
MV 6TURBINE STATUS CODETurbine state (slow roll, running, cooldown)Read
MV 5UNIT CONTROL SOURCEControl source; ISN (BAS) for BMS controlRead
AV 5LEAVING CHW TEMPLeaving chilled water temperatureRead
AV 20COMPRESSOR PRV POSITIONPre-rotation vane position, % (load)Read
MV 2UNIT SAFETY FAULT CODESafety shutdown code (1 = none)Read
MV 3UNIT CYCLING FAULT CODECycling shutdown code (1 = none)Read

Enable & remote start

BV 1 REM RUN STOP CMD (0 = Stop, 1 = Run) is the BAS run/stop, and AV 1-2 are the remote setpoints. MV 5 Unit Control Source shows Local, ISN, Analog, Digital or Modem, and BV 20 shows the remote-mode ready-to-start contacts. The points list has no write-enable point and doesn't say how the source is chosen at the chiller panel.

Network setup

Watch out for

York YST Steam Turbine Chiller (SC-EQ) BACnet objects

Type: AI, AO, AV, BI, BO, BV, MI/MO/MV (multi-state) · Access: Read read-only, Write writable, Command writable with a priority array.

Note: the source document has no read/write column, so access here is inferred from the object type (inputs read-only, values writable). Confirm on the live controller before writing.

74 of 74 shown
Type
AnalogBinaryMulti-state
Access
Show
York YST Steam Turbine Chiller (SC-EQ) BACnet Points List
DescriptionStates
AVmin1REM LEAVING CHW TEMP SPRemote Leaving Chilled Liquid Setpoint°FCommand
AVmin2TURBINE HP LIMIT SPTurbine Horsepower Limit Setpoint%Command
BVmin1REM RUN STOP CMDRemote Run/StopCommand0=Stop, 1=Run
MV65001UnitsUnit system reported by the SC-EQWrite0=IP (English), 1=SI (Metric)
AVmin5LEAVING CHW TEMPLeaving Chilled Liquid Temperature°FRead
AV6ENTERING CHW TEMPReturn Chilled Liquid Temperature°FRead
AV7EVAPORATOR PRESSUREEvaporator PressurePSIGRead
AV8CONDENSER PRESSURECondenser PressurePSIGRead
AV9COMPR OIL COMP DIF PRESSCompressor Oil PressurePSIGRead
AV10ENTERING COND WATER TEMPEntering Condenser Liquid Temperature°FRead
AV11LEAVING COND WATER TEMPLeaving Condenser Liquid Temperature°FRead
AV12TURBINE INLET STEAM TEMPTurbine Inlet Steam Temperature°FRead
AV13TURBINE INLET STEAM PRESTurbine Inlet Steam PressurePSIGRead
AV14TURBINE SUPPLY OIL TEMPTurbine Supply Oil Temperature°FRead
AV15TURBINE SUPPLY OIL PRESSTurbine Supply Oil PressurePSIGRead
AV16TURBINE 1ST STG STM PRESTurbine First Stage Steam PressurePSIGRead
AV17TURBINE SPEEDTurbine SpeedRPMRead
AV18TURBINE EXHAUST STM PRESTurbine Exhaust Steam PressurePSIARead
AV19LEAVING CHW TEMP ACT SPLeaving Chilled Liquid Temperature Setpoint - Local°FRead
AVmin20COMPRESSOR PRV POSITIONCompressor PRV Position%Read
AV21EVAP SATURATION TEMPChiller Evaporator Saturation Temperature°FRead
AV22COND SATURATION TEMPChiller Condenser Saturation Temperature°FRead
AV23DISCHARGE TEMPCompressor Discharge Temperature°FRead
AV24OIL SUMP TEMPERATURECompressor Sump Oil Temperature°FRead
AV25SUBCOOLER REFRIG LEVELSubcooler Refrigerant Level%Read
AV26ACCUM OPERATING HOURSAccumulated Operating HoursHrRead
AV27ACCUM SYSTEM STARTSAccumulated System StartsRead
AV28OIL SUMP PRESSURECompressor Sump Oil Transducer PressurePSIGRead
AV29OIL PUMP PRESSURECompressor Pump Oil Transducer PressurePSIGRead
BV5PANEL ROCKER SW RUNPanel Rocker Switch - RunRead0=Off, 1=On
BV6PANEL ROCKER SW STOPPanel Rocker Switch - Stop / ResetRead0=Off, 1=On
BV7CHW LIQ PUMP STATChilled Liquid Pump Start ContactsRead0=Off, 1=On
BV8COND LIQ PUMP STATCondenser Liquid Pump Start ContactsRead0=Off, 1=On
BV9CHW FLOW SWITCH STATChilled Liquid Flow Switch ContactsRead0=Off, 1=On
BV10COND LIQ FLOW SW STATCondenser Liquid Flow Switch ContactsRead0=Off, 1=On
BV11COND REFRIG HI PRESS COCondenser Refrigerant High Pressure CutoutRead0=Off, 1=On
BV12COMP OIL HEATER CONTCompressor Oil Heater ContactorRead0=Off, 1=On
BV13COMP OIL RETURN SOL VLVCompressor Oil Return Solenoid ValveRead0=Open, 1=Closed
BV14COMP OIL COOLER W SOL VLCompressor Oil Cooler Water Solenoid ValveRead0=Open, 1=Closed
BV15COMP VAR SPD OIL PMP RUNCompressor Variable Speed Oil Pump Run ContactsRead0=Off, 1=On
BV16COMP VAR SPD OIL PMP AUXCompressor variable-speed oil pump auxiliary contactsRead0=Off, 1=On
BV17COMPR LIQ INJ SOL VLVCompressor Liquid Injection Solenoid ValveRead0=Open, 1=Closed
BV18COMPR HS THRUST SOLCompressor High Speed Thrust SolenoidRead0=Open, 1=Closed
BV19CLOSED LIMIT SWITCHClosed Limit SwitchRead0=Off, 1=On
BV20REM MODE READY TO STARTRemote Mode Ready To Start ContactsRead0=Off, 1=On
BV22TURBINE ROTATING CONTTurbine Rotating ContactsRead0=Off, 1=On
BV23TURBINE TRIP SOL VLVTurbine Trip Solenoid ValveRead0=Open, 1=Closed
BV24TURBINE TRIP VLV CLO LSTurbine Trip Valve Closed Limit SwitchRead0=Off, 1=On
MVmin1UNIT OPERATION CODEUnit Operation CodeRead1=Unit Stopped - Ready To Start, 2=Unit Stopped - Local Shutdown, 3=Unit Stopped -Remote Shutdown, 4=Unit Stopped Warning Active, 5=Unit Stopped - Cycling Shutdown, 6=Unit Stopped - Safety Shutdown, 7=Unit Start Inhibit, 8=Unit Starting, 9=Unit Running - No Abnormal Condition, 10=Unit Running - Warning Active, 11=Unit Running - Chiller Unload Before Shutdown, 12=Unit Coastdown / Lockout Delay, 13=Unit Stopped - Turbine Cooldown, 14=Unit Stopped - Internal Shutdown
MVmin2UNIT SAFETY FAULT CODEUnit Safety Shutdown CodeRead1=No Malfunction, 2=Evaporator - Low Pressure, 3=Evaporator - Transducer Or Leaving Liquid Probe, 4=Evaporator - Transducer Or Temperature Sensor, 5=Evaporator - Low Temperature, 6=Evaporator - Low Pressure - Smart Freeze, 7=Condenser - High Pressure Contacts Open, 8=Condenser - High Pressure, 9=Condenser - Pressure Transducer Out Of Range, 10=Auxiliary Safety - Contacts Closed, 11=Control Panel - Power Failure (Manual Restart), 12=Discharge - Low Temperature, 13=Discharge - High Temperature, 14=Compressor Oil - High Temperature, 15=Compressor Oil - Low Differential Pressure, 16=Compressor Oil - High Differential Pressure, 17=Compressor Oil - Pump Press Xdcr Out Of Range, 18=Compressor Oil - Sump Press Xdcr Out Of Range, 19=Compressor Oil - High Pressure, 20=Compressor Oil - Differential Pressure Calibration, 22=Oil - Variable Speed Pump - Setpoint Not Achieved, 23=Thrust Bearing - Proximity Probe Clearance - Fwd, 24=Thrust Bearing - Proximity Probe Clearance - Rev, 25=Thrust Bearing - Proximity Probe Uncalibrated, 26=Thrust Bearing - Proximity Probe Out Of Range, 27=Thrust Bearing - Limit Switch, 29=Turbine - Low Oil Pressure, 31=Turbine - High Oil Temperature, 33=Turbine - Governor End Bearing High Temperature, 34=Turbine - Shaft End Bearing High Temperature, 35=Turbine - Governor End Vibration, 36=Turbine - Shaft End Vibration, 37=Turbine - High Inlet Steam Pressure, 38=Turbine - High Exhaust Steam Pressure, 39=Turbine - Hotwell Low Level, 40=Turbine - Hotwell High Level - Analog, 41=Turbine - Hotwell Pump Failure, 42=Turbine - Vacuum Seal Failure, 43=Turbine - Vacuum Pump Failure, 44=Turbine - High Vacuum Pressure, 45=Turbine - Underspeed While Starting, 46=Turbine - Underspeed While Running, 47=Turbine - Steam Supply Valve Malfunction, 48=Turbine - Overspeed, 49=Turbine - Mechanical Overspeed Test Failure, 50=Turbine - Underspeed Dip While Starting, 51=Turbine - Underspeed Dip While Running, 52=Turbine - Excessive Slow Roll, 53=Turbine - Mechanical Trip, 54=Turbine - Excessive Start Delay, 55=Turbine - Shaft Bearing Temperature Out Of Range, 56=Turbine - Oil Temperature Out Of Range, 57=Turbine - Oil Pressure Out Of Range, 58=Turbine - Hotwell High Level - Digital, 59=MPU Failure, 60=Slow Roll Overspeed, 61=Turbine - Governor End Horizontal Vibration, 62=Turbine - Governor End Vertical Vibration, 63=Turbine - Shaft End Horizontal Vibration, 64=Turbine - Governor End Vertical Vibration, 65=Turbine - Govr End Horiz Vibration Out of Range, 66=Turbine - Gov End Vert Vibration Out of Range, 67=Turbine - Shaft End Horiz Vibration Out of Range, 68=Turbine - Gov End Vert Vibration Out of Range, 69=Compressor - Horiz Vibration Out of Range, 70=Compressor - Vertical Vibration Out of Range, 71=Safety Shutdown- Steam Supply Out of Range
MVmin3UNIT CYCLING FAULT CODEUnit Cycling Shutdown CodeRead1=No Malfunction, 3=Remote Cycling, 4=Low Compressr Oil Differential Temperature, 5=Low Compressr Sump Oil Temperature, 6=Control Panel - Power Fail (Autostart), 7=Evaporator - Low Chilled Liquid Temperature, 8=Evaporator - Flow Switch Open, 9=Chiller Condenser - Flow Switch Open, 10=Control Panel - Schedule Shutdown, 11=Proximity Probe - Low Supply Voltage, 12=Oil - Variable Speed Pump - Drive Contacts Open, 13=Expansion I/O Serial Communications
MV4UNIT WARNING FAULT CODEUnit Alarm / Warning CodeRead1=No Malfunction, 2=Real-Time Clock Failure, 3=Setpoint Override, 5=Condenser Or Evaporator Transducer Error, 6=Evaporator - Low Pressure Limit, 7=Consenser - High Pressure Limit, 8=Condenser Transducer Error, 9=Freeze Threat From Operating Chiller, 10=Refrigerant Level Out Of Range, 11=Seal Lubrication In Process, 12=Standby Lube - Low Oil Pressure, 14=Turbine - High Condensate Level, 15=Turbine - Oil Low Pressure, 16=Turbine - Auxiliary Oil Low Pressure, 17=Turbine - Oil High Temperature, 19=Turbine - Auxiliary Oil Pump Overrun, 20=Turbine - Speed Sensor Differential, 21=Turbine - Governor End Bearing High Temperature, 22=Turbine - Shaft End Bearing High Temperature, 23=Turbine - Governor End Vibration, 24=Turbine - Shaft End Vibration, 25=Turbine - Inlet Steam High Pressure, 26=Turbine - Exhaust Steam High Pressure, 27=Turbine - Hotwell Low Level, 28=Turbine - Hotwell High Level, 29=Turbine - Hotwell Lead Pump, 30=Turbine - Vacuum Lead Seal, 31=Turbine - Vacuum Lead Pump, 32=Turbine - Vacuum High Pressure, 33=Turbine - High Condensate Drain Level, 34=Mechanical Overspeed Test in Progress, 35=Vacuum Pump Overrrun, 36=Turbine - Governor End Horizontal Vibration, 37=Turbine - Governor End Vertical Vibration, 38=Turbine - Shaft End Horizontal Vibration, 39=Turbine - Governor End Vertical Vibration, 40=Evaporator Low pressure Override, 41=Condenser High pressure Override, 42=Turbine Power Limiter Override, 43=Auto Capacity Control Unavailable, 44=Condenser or VGD sensor Failure, 45=Conditions Override VGD
MVmin5UNIT CONTROL SOURCEUnit Control SourceRead0=Local, 1=ISN, 2=Analog, 3=Digital, 4=Modem
MVmin6TURBINE STATUS CODETurbine Status CodeRead1=Stopped, 2=System Starting, 3=Ready to Begin Slow Roll (Manual), 4=Waiting for Steam Flow (Manual) / System Starting (Auto) / Slow Rolling, 5=Turbine Idling - High Exhaust Pressure, 6=Ready to Run (Manual), 7=Ready to Run (Auto) / Ramping to Rated Speed, 8=Stabilizing, 9=Running, 10=Unloading Before Shutdown, 11=Compressor Shutdown; Turbine Cooldown
MV7UNIT MODIF RUN FLT CODEUnit Modified Run Fault CodeRead1=No Modified Run Conditions Present, 2=Leaving Chilled Liquid Control, 3=Vanes Closing Before Shutdown, 4=Slide Valve Unloading before Shutdown, 5=Seal Lube in Process
MV8UNIT INHIBIT FAULT CODEUnit Inhibit Fault CodeRead1=No Start Inhibits Present, 2=Vane Motor Switch Open, 3=Turbine Vibration Sensor Fault, 4=Vanes Uncalibrated, 5=Compressor Vibration Sensor Fault
MV9UNIT INTERNAL FAULT CODEUnit Internal Fault CodeRead1=No Internal Faults Present, 2=Internal Error- No timer Handles Available, 3=Watchdog- Software Reboot, 4=Internal Error- Cannot create Task
AV30THRUST BEARING PROX POSHigh Speed Thrust Bearing Proximity PositionRead
AV31THRUST BEARING PROX REFHigh Speed Thrust Bearing Proximity ReferenceRead
AV32TURBINE GOV END BRG TEMPTurbine Governor End Bearing Temperature°FRead
AV33TURBINE SHF END BRG TEMPTurbine Shaft End Bearing Temperature°FRead
AV34HOTWELL CONDENSATE LVLHotwell Condensate Level%Read
AV35EVAP REFRIG LIQ TEMPEvaporator Refrigerant Liquid Temperature°FRead
AV36COND REFRIG LIQ TEMPCondenser Refrigerant Liquid Temperature°FRead
AV37CHILL LIQ FLOW SENSORChilled Liquid Flow SensorGPMRead
AV38COND LIQ FLOW SENSORCondenser Liquid Flow SensorGPMRead
AV39STEAM FLOW SENSORSteam Flow SensorLb/HrRead
AV40HOTGAS BYPASS VLV POSHotgas Bypass Valve Position%Read
AV41GOVERNOR VLV POSGovernor Valve Position%Read
AV43SLOW ROLL TIME REMAININGSlow Roll Time RemainingMinRead
BV26TURBINE AUX OIL PMP CONTTurbine Auxiliary Oil Pump ContactorRead0=Off, 1=On
BV27TURBINE AUX OIL PMP CONATurbine auxiliary oil pump contactor auxiliary contactRead0=Open, 1=Closed
BV28TURBINE OIL CLRW SOL VLVTurbine Oil Cooler Water Solenoid ValveRead0=Off, 1=On
BV29ALARM HORNAlarm HornRead0=Off, 1=On

Integration notes

Check it against the live device. A points list tells you what the controller can expose; the unit in front of you may differ by firmware or installed options. Easy BACnet scans a network for BACnet IP devices from an Android phone, reads every object on the YST Steam Turbine Chiller (SC-EQ) and exports what it actually has to Excel — free. New to BACnet? Start with what a BACnet points list is and what the object types mean.

Questions about the York YST Steam Turbine Chiller (SC-EQ)

How many BACnet points does the York YST Steam Turbine Chiller (SC-EQ) have?

This list has 74 BACnet objects: 40 analog values, 24 binary values, 10 multi-state values. The exact set on a given unit depends on its firmware, installed options and configuration.

Which York YST Steam Turbine Chiller (SC-EQ) BACnet points are writable?

4 of the 74 objects accept a write. Points marked Command have a priority array: a write holds until it is released, so release it back to automatic when you are done. The source has no read/write column, so this is inferred from object type.

Where is the official York YST Steam Turbine Chiller (SC-EQ) BACnet documentation?

The source is YST SC-EQ BAS Points List, revision Rev 1.2, 2021-12-08, published free by York at https://docs.johnsoncontrols.com/chillers/api/khub/documents/xdkEW8x~Tlf_XJgFpLpcbA/content.

What are the minimum BACnet points to integrate the York YST Steam Turbine Chiller (SC-EQ)?

Start with BV 1 REM RUN STOP CMD (Remote run/stop (1 = run)); AV 1 REM LEAVING CHW TEMP SP (Remote leaving chilled water setpoint); AV 2 TURBINE HP LIMIT SP (Turbine horsepower limit, % (demand limit)); MV 1 UNIT OPERATION CODE (Operating state (stopped, starting, running)); MV 6 TURBINE STATUS CODE (Turbine state (slow roll, running, cooldown)); MV 5 UNIT CONTROL SOURCE (Control source; ISN (BAS) for BMS control); AV 5 LEAVING CHW TEMP (Leaving chilled water temperature); AV 20 COMPRESSOR PRV POSITION (Pre-rotation vane position, % (load)); MV 2 UNIT SAFETY FAULT CODE (Safety shutdown code (1 = none)); MV 3 UNIT CYCLING FAULT CODE (Cycling shutdown code (1 = none)).

How do I enable BMS control of the York YST Steam Turbine Chiller (SC-EQ)?

BV 1 REM RUN STOP CMD (0 = Stop, 1 = Run) is the BAS run/stop, and AV 1-2 are the remote setpoints. MV 5 Unit Control Source shows Local, ISN, Analog, Digital or Modem, and BV 20 shows the remote-mode ready-to-start contacts. The points list has no write-enable point and doesn't say how the source is chosen at the chiller panel.

How do I check these points on the real YST Steam Turbine Chiller (SC-EQ)?

Scan the network with a BACnet IP browser such as Easy BACnet, open the device and compare its object list with this table. Anything missing is usually an option that isn't installed or a point that is disabled in the controller's configuration.

More York BACnet points lists

Source: YST SC-EQ BAS Points List · rev. Rev 1.2, 2021-12-08. Object names, instances and units are reproduced as published; descriptions are our own.