VAV Air System

AHU Flow Sensor

Object/Prop. Ref

This property defines an optional binary sensor input that can be used to confirm the fact that the AHUs are really Off.

Air Valve Drive Closed: Ref

Property Reference

This property indicates the value to be used by the BCU to determine which value to communicate to the UCM for the air valve drive closed override.

Air Valve Drive Max: Ref

Property Reference

This property indicates the value to be used by the BCU to determine which value to communicate to the UCM for the air valve drive maximum override.

Air Valve Drive Min: Ref

Property Reference

This property indicates the value to be used by the BCU to determine which value to communicate to the UCM for the air valve drive minimum override.

Air Valve Drive Open: Ref

Property Reference

This property indicates the value to be used by the BCU to determine which value to communicate to the UCM for the air valve drive open override.

Auto Heat Cool Input

Referencer/ Multi-State

This value either specifies the explicit heating or cooling mode of the VAV Air System, or grants permission to VAS to dynamically determine the heating or cooling mode of the VAV Air System.

Control Event Class

Numeric

Contains the Alarm and Message Routing Class number (1–20) that is used to route messages when this object is controlled.

Cooling Setpoint

Referencer/ Numeric

The temperature that the VAV Air System is to maintain during cooling.

Delay Start Time

Date/Time Numeric

BCU use only

Delay Stop Time

Date/Time Numeric

BCU use only

Last Control Date Time

Date/Time Numeric

This indicates the date and time when the present value property of this object was last controlled.

Heating Setpoint

Referencer/ Numeric

The temperature that the VAV Air System is to maintain during heating.

Max Flow if VAS Heating

Binary

This property indicates whether or not the VAS will drive its member VAVs to Max if the VAS mode is HEATING.

Min Night Econ Off

Numeric

Indicates the threshold value (equal to or less than) of Night Economizer mode votes that the VAS must have remaining before it will propagate a mode of lesser rank than Night Economizer to the AHU.

Min Night Econ On

Numeric

Indicates the threshold value (equal to or greater than) of Night Economizer mode votes that the VAS must accumulate before it will propagate a VAS status of Night Economizer to the AHU.

Min Night Heat/Cool Off

Numeric

Indicates the threshold value (equal to or less than) of Night Heat/Cool mode votes that the VAS must have remaining before it will propagate a mode of lesser rank than Night Heat/Cool to the AHU.

Min Night Heat/Cool On

Numeric

Indicates the threshold value (equal to or greater than) of Night Heat/Cool mode votes that the VAS must accumulate before it will propagate a VAS status of Night Heat/Cool to the AHU.

Minimum Flow

Numeric

Indicates the minimum flow at which the associated AHU can be operated. The VAS will enforce the rule that the AHU will never be operated at a lower flow. When the aggregate demand of the VAVs falls below this level, the AHUs are turned Off, and when the aggregate demand rises above this level, the AHUs are turned On.

Mode: Heat/Cool

Multi-State

Current heating/cooling mode of the VAV Air System. Indicates whether the AHU is in the heating or cooling mode.

Morning Warmup Differential

Numeric

The number of degrees below the morning warmup setpoint to re-initiate heat after initial startup.

Morning Warmup Sensor

Referencer/ Numeric

The temperature input to be used in the algorithm to decide if the VAV Air System is in heating or cooling mode (assuming that the Auto/Heat/Cool input is "Auto").

Morning Warmup Setpoint

Referencer/ Numeric

The temperature setpoint to be used in the algorithm to decide if the VAV Air System is in heating or cooling mode (assuming that the Auto/Heat/Cool input is "Auto").

Object Identifier

Object ID

Unique hexadecimal ID of this object. This ID is used internally to identify the object.

Object Type

Multi-State

Designates object’s type (i.e., analog input, binary output, TCM, PCM, etc.).

Pneumatic VAV Output

Object/Prop. Ref

This property is an Object ID to be turned On whenever the VAS Air System is Occupied or in Coastdown (i.e., the AHU is On) and in cool mode. Whenever the VAV Air System is Unoccupied or in Coastdown (i.e., the AHU is Off) this object is to be turned Off. This controls the pneumatic air supply to normally open non-Trane VAV boxes.

Present Value

Multi-State

Current value of the VAV Air System.

Startup Time Delay

Numeric

Indicates the number of minutes that the VAV Air system will delay the propagation of a VAS mode to the AHU when the new mode represents a transition from an AHU Fan Off state to an AHU Fan On state. This is to give the VAVs time to open their dampers before the AHU fans turn on.

Static Pressure Setpoint

Referencer/ Numeric

Indicates the static pressure that the VAV Air System is to maintain during operation.

Stop Time Delay

Numeric

Indicates the number of minutes that the VAV Air system will wait after initiating the shutdown of the AHUs before allowing the mode change of a VAV to a mode that represents an AHU Fan Off state. This is to give the AHU fans time to stop before the VAVs close their dampers.

Subordinate Vasecto

Object Ref

Not applicable.

Supply Air Temp: Ref

Property Reference

This property indicates the value to be used by the BCU to determine which value to communicate to the UCM for the supply air temp.

Supply Air Temperature

Numeric

This property indicates the active value of the supply air temperature currently being used by the VAS. This value is sent to VAV II/III objects which are members. VAV II/III objects given a supply air temp will determine a heat/cool control action based on a comparison of supply air temp and zone temp.

Update Tag

Numeric

Value indicating last edit change of this object.

VAV Control Offset

Numeric

Indicates the number of whole degrees that the heating setpoints should be decreased by and the cooling setpoints increased by when a given VAV has its setpoints offset or "relaxed" when it is placed into demand limit, or coastdown mode. Conversely, when a VAV that has had its setpoints offset returns to any other mode, it must have its setpoints adjusted accordingly by this amount.