CET extract air VAV box, pressure sensor, duct area, venturi valve (CetVavEx15)

Overview

The application function "CET room pressurization extract air VAV box 15, differential pressure sensor, duct area, internal air flow controller, venturi valve" (CetVavEx15) operates a venturi air valve, using both closed loop and open loop control to drive the measured flow to an airflow setpoint (VavExSpAirFl) that it calculates from a received signal indicating demand for extract flow from the room. It can control airflow with a settling time of 1 to 2 seconds when applied with the right peripheral devices. It can also be set up for slower operation.

The main output is a modulating output for venturi air valve position (VavExPos) that is generated by a PID airflow controller in this AF. Functions to support air balancing and venturi air valve calibration are included.

Note
To calculate extract air volume flow, this AF uses a duct areacalculation and input from a differential pressure sensor.

Main features:

VAV extract damper modulation for non critical room pressurization
Extract air volume flow setpoint calculation
Extract air volume flow calculation
Airflow coefficient calculation (air balancing logic)

Function

The figure below shows BACnet objects associated with this application function. Primary signal flow is summarized as follows:

Basic function: Accept the extract airflow demand signal (VavExVntReq) from associated room pressurization controller and map it to the extract airflow setpoint (VavExSpAirFl). Pass the result through a device mode logic switch prior to outputting as a command to the object (VavExPos) that controls the device.

	Command or request (or related)
	Notification of condition or status, or availability
	Device mode

Device mode: The input signal for device mode is a multistate value.

VavExDevMod supports the following states:

Off
Control mode
Max.air vol.flow
Min.air vol.flow
Smoke ctrl.air flow setp.

Available status: When the VAV extract damper is available for extract air ventilation, the binary output signal that indicates availability (VavExVntReq) will be "Yes" (available).

For available status to be "Yes", device mode must equal "Control mode" (modulation).

Airflow control loop (cascade control)

Airflow controller: The PID airflow controller (VavSuAirFlCtr) compares the airflow volume of the Venturi valve to the current VAV extract airflow setpoint, and modulates VavSuPos as necessary to keep the box flow at setpoint.

ABT 5.x and later:

Airflow setpoint selection: The AF calculates the airflow setpoint for the terminal to satisfy the demand of one of the supported airflow drivers:

Heating
Cooling
Ventilation
Make-up

The AF maps the demand level in percent to the flow range (min/max values) configured for the active driver. The result is the airflow setpoint for the terminal in physical flow units (ft³/min, m³/h, l/s). Mapping of the demand level to the flow range is as shown in the diagram.

The objects indicating demand level, (VavSuAirFlReq) and the active driver (VavSuAflScale) are inputs to the AF. They are written by other functions. The airflow limits for the terminal are configured here.


Cooling	Heating

Ventilation	Make-up

That setpoint mapping is normal operation. It applies when the device mode (VavSuDevMod) is Control Mode. Special values of device mode alter the setpoint as follows:

Off – Setpoint is 0 and damper is closed
Control Mode – Setpoint follows % demand
Maximum airflow setpoint – Setpoint is maximum for the currently active airflow scale
Minimum airflow setpoint – Setpoint is minimum for the currently active airflow scale
Manual airflow setpoint – Setpoint is value configured for smoke control

Supply Air Flow Limits for Air Terminals - Configuration

The Supply Air Flow serves multiple functions: heating, cooling, ventilation, and pressurization. The following section explains how to configure each supply terminal for different use cases.

	Cooling	Heating	Ventilation
Single CV (Constant Volume) Supply Terminal	Min = Max = 0 (or minimum flow value needed for the coil to cool the room)	Min = Max = 0 (or minimum flow value needed for the coil to heat the room)	Min = 0 Max ≥ The largest value configured in Ventilation AF
Single VAV (Variable Air Volume) Supply Terminal (no fume hood)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max Ventilation ≥ Largest value configured in Ventilation AF
Single VAV Supply Terminal (fume hood)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min Ventilation = 0 Max Ventilation ≥ Largest value configured in Ventilation AF or value needed to balance maximum fume hood flow

Check the project specification to see if the various terminals are to be sequenced differently from each other: if they respond to different needs. If no difference is specified, follow the next table's instruction. If the flow limits are set the same for each terminal, then they run at equal flows.

	Cooling	Heating	Ventilation
Multiple Supply Terminals (same size, same function)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule (specified per terminal)	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max ≥ The largest of configured ventilation levels for the room and the supply flow needed to balance fume hoods, divided by the number of supply terminals

Check the project specification to see if the various terminals are to be sequenced differently from each other: if they respond to different needs. If the supply terminals are different sizes but have the same function, follow the next table's instruction.

	Cooling	Heating	Ventilation
Multiple Supply Terminals (different sizes, same function)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule (specified per terminal)	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max ≥ 1. The largest value of the terminal being configured or 2. The value needed to balance maximum fume hood flow of the terminal being configured

In the case of multiple supply terminals with different functions, the following tables provide an example of how to configure one CV (Constant Volume) Terminal serving a chilled beam, and one VAV (Variable Air Volume) Terminal without cooling.

Flow through the CV Terminal does not vary to heat or cool.
Flow is always set by ventilation or support for coil (minimum heat or minimum cooling) unless reducing it is the only way to maintain room pressurization.

Flow through the VAV Terminal may vary for heating, cooling, and ventilation, or to balance fume hood flow.

	Cooling	Heating	Ventilation
Multiple Supply Terminals (different functions) CV Terminal	Min = Max = 0 (or minimum flow value needed for the coil to cool the room)	Min = Max = 0 (or minimum flow value needed for the coil to heat the room)	Min = Max = 0 (or value needed to support a heating or cooling coil)
Multiple Supply Terminals (different function) VAV Terminal	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule (specified per terminal)	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max ≥ 1. The largest value of the terminal being configured or 2. The value needed to balance maximum fume hood flow of the terminal being configured

ABT 4.x and earlier

Airflow setpoint selection: The AF calculates the airflow setpoint for the terminal to satisfy the demand of one of the supported airflow drivers:

Heating
Cooling
Ventilation
Make-up


Cooling	Heating

Ventilation	Make-up

That setpoint mapping is normal operation. It applies when the device mode (VavSuDevMod) is Control Mode. Special values of device mode alter the setpoint as follows:

Off – Setpoint is 0 and damper is closed
Control Mode – Setpoint follows % demand
Maximum airflow setpoint – Setpoint is maximum for the currently active airflow scale
Minimum airflow setpoint – Setpoint is minimum for the currently active airflow scale
Manual airflow setpoint – Setpoint is value configured for smoke control

Airflow control with Venturi air valve: The AF has three ways to control airflow with the Venturi valve: PID control, a linear characterization curve, and the linear characterization curve combined with PID control. The user selects the loop control by setting the configuration property (AirFlCtlMod) and by setting up the data table for the characterization curve.

AirFlCtlMod	Characterization Curve	Setpoint	Control action
closed loop	configured	> AirVMinCtlClb	combined
closed loop	configured	< AirVMinCltClb	curve only
closed loop	not configured	any	PID only
closed loop	configured	any	curve only
closed loop	not configured	any	fail mode
open loop	configured	> AirVMinCtlClb	curve only
open loop	configured	< AirVMinCltClb	curve only
open loop	not configured	> AirVMinCtlClb	curve only (output to actuator will be zero)
open loop	not configured	< AirVMinCltClb	curve only (output to actuator will be zero)
open loop	configured	any	curve only
open loop	not configured	any	fail mode
--	calibrating	--	curve

PID control: The PID control will be used when the closed loop configuration is selected and the characterization table has not been configured.

The PID controller is fixed in the modulating mode. Two-position operation, if needed, is achieved by providing a 2-position setpoint signal.

Linear characterization curve: Open loop control, by the 15 point linear characterization curve will be used to position the venturi when open loop control is selected.

Open loop control is also active if the user selects closed loop control and the airflow setpoint equates to an velocity setpoint of less than the minimum control velocity (AirVMinCtlClb). The default setting is 1.778 m/s (350 fpm).

The x and y points for the linear characterization curve can be entered manually or they can be automatically entered by running the venturi calibration.

Linear characterization curve with PID: Combined control applies when configured closed loop control is selected and the characterization curve is configured, and the airflow setpoint, the duct velocity is above the minimum velocity for control.

When the setpoint changes quickly, and both calculation paths respond, the system is likely to overshoot. To reduce this tendency, the setpoint signal to the PID controller is delayed to arrive in synch with change in airflow caused by the open loop actuator movement. For most effective operation, users should adjust the delay (TiConSpAflRel) to correspond to the stroke time of the actuator.

Flow sensor failure: If the airflow sensor object is invalid (not including over range) then, the flow control damper position will be set based on the setting of the configuration extension AirFlFailMod.

If AirFlFailMod is set to Hold, the damper will stay in the current position.
If AirFlFailMod is set to Open, the damper position will be set to 100%.
If AirFlFailMod is set to Close, the damper position will be set to 0%.

While the sensor is failed, PID operation is suspended. When status of the sensor is valid again, the PID resumes operation.

When the AI is unreliable, airflow calculations continue, however, airflow value might not change because the value of the AI stops updating. The AF also sets a binary value object indicating normal or faulty state of the airflow data.

Network communication loss: If network communication loss occurs, the flow setpoint will be set based on the setting of the configuration extension AirFlFailMod.

If AirFlFailMod is set to Hold, the flow setpoint will stay in the current position.
If AirFlFailMod is set to Open, the flow setpoint will be set to the maximum flow of the mode the terminal was in during failure.
If AirFlFailMod is set to Close, the flow setpoint will be set to the minimum flow of the mode the terminal was in during failure.

When the network communication is lost, the flow control loop continues to operate with the setpoint selected from above.

Flow sensor failure with characterization curve: If the controller detects flow sensor failure (not including over range) it switches to control by the characterization curve alone.

Sensor calibration: While the airflow sensor is in active calibration, the acitve flow control is suspended; the output does not change and the integrator does not increment. This applies to closed loop control. When the status returns to normal, there may be a bump in output due to proportional action.

Open loop control (with characterization curve) continues to operate, and may move the actuator during calibration.

Airflow sensing: The AF calculates volumetric airflow from a measured differential pressure value and supports other functions associated with the airflow sensor. It supports manual operations associated with air balancing and works with the APS and other pressure sensors, that includes an Auto-zero function. The AF does not include calculations or data to zero a sensor.

When the velocity in the duct is low (below AirVMinCtlClb) the controller uses the value from the characterization curve, rather than the flow measurement to command the airflow object.

Low sensor value: Configuration settings specify a switch-on point and hysteresis value in units of pressure.

In Venturi applications, this feature has no effect because the cut out velocity for the sensor is much lower than the value where the controller switches to the calibration curve.

If the AI object representing the DP sensor indicates a failure and the characterization curve is configured, the controller switches to the Venturi air valve for flow data. The calculated value object, representing airflow shows the value from the characterization curve, and the reliability of that object does not indicate a problem. Other values derived from the flow value also indicate reliable data.

Duct area calculation: The duct area is calculated based on configuration data.

Airflow coefficient: The airflow coefficient is configuration data (VavSuFlCoef). Users may enter the coefficient directly or enter their own, independent airflow readings and have the AF calculate and set the flow coefficient.

Air balancing: Balancing functions are not connected with the air pressurization functions.The air balancing functions are:

Set flow setpoint according to selected balancing mode.
Calculate duct area
Calculate flow coefficient.
Apply airflow coefficient.
Restore automatic operation.
Record data for balancing report.

Balancing functions are not connected with room pressurization functions. It is expected that the room may lose pressurization when the balancer performs balancing steps.

Supply chain interface: There are two supply chain output signals.

Airflow deviation signal: The supply airflow deviation (VavExAirFlDvn ) signal (in percent) is used for fan speed (static pressure) reset strategies at the air handling unit. It is obtained by measuring the airflow from the supply duct and comparing it to the airflow setpoint.

VavExAirFlDvn = VavExSpAflRel minus VavExAirFlRel

VavExAirFlDvn will equal 0 in case of invalid condition(s).

Saturation signal: The saturation signal VavExAflStrtn is a binary object that is True ("Starved") when the airflow control loop cannot get enough air to reach setpoint for a time exceeding a built-in time delay. After the delay expires, open loop operation begins.

Note
VavExAflStrtn is always off if parameter EnStrtnCal = 0 (No). This allows the user to exclude a particular terminal from the saturation pressure reset system.

In order for Saturation Signal to be True:
1. The Enable Saturation Calibration parameter must be set to Yes (EnStrtnCal=Yes)
2. The output of the VAV controller must be greater than the saturation level (VavExAirFlCtr>StrtnLvl)
3. The air flow error, which is the setpoint minus airflow value, must be greater than the air flow error limit (AirFlEr>AirFlErLm)

Saturation Signal can only be True when all three parts are satisfied for the duration of DlyOnStrtn.

The minimum and maximum airflow setpoints are entered in this application function. A group member object in the segment transmits the values to the room application.

Configuration

Objects

Description	Object	Type	Default value
Extract air VAV balancing state ▶ Indicates the state of progress of the balancing process for this VAV box; is written by the controller in response to the user-entered balance command; persists through a power cycle. 1:Initial 2:Balancing 3:Balanced	VavExBalSta	MCnfVal	1:Initial
Extract air VAV balancing mode ▶ Air flow value set by the air balancer person to select the airflowsetpoint value used when the balancing state = balancing. 1:Maximum ventilation 2:Minimum ventilation 3:Smoke	VavExBalMod	MCnfVal	1:Maximum ventilation
Extract air VAV air volume flow at hood ▶ Externally measured airflowvalue, entered by air balancer, used to calculate flow coefficient.	VavExAirFlHood	ACnfVal	100 [m³/h] 58.9 [ft³/min] 27.78 [l/s]
Extract air VAV recorded balancing mode ▶ Stored value for balance report; balance mode value at time of record trigger. Enumeration see VavExBalMod	VavExBalModRec	MCnfVal	1:Maximum ventilation
Extract air VAV recorded air volume flow at hood ▶ Stored value for balance report; hood flow value at time of record trigger.	VavExAflHodRec	ACnfVal	0 [m³/h] 0.0 [ft³/min] 0.00 [l/s]
Extract air VAV recorded flow coefficient ▶ Stored value for balance report; flow coefficient value after Calibrate trigger.	VavExFlCoefRec	ACnfVal	0.000
Extract air VAV initial flow coefficient ▶ The value of flow coefficient as found prior to balancing; this value is recorded when the user-entered Balancing Command is set to Balancing.	VavExFlCoefIni	ACnfVal	0.000
Extract air VAV recorded air volume flow ▶ Stored value, for balance report, of the current, calculated air flow.	VavExAirFlRec	ACnfVal	0 [m³/h] 0.0 [ft³/min] 0.00 [l/s]
Extract air VAV recorded position ▶ Stored value of the extract damper position at the time of the record trigger.	VavExPosRec	ACnfVal	0 [%]
Extract air VAV duct area ▶ Duct cross-sectional area, user-entered or calculated by controller using the duct shape, dimension A and dimension B values. 0...1 [m²], 0.0...10.76 [ft²]	VavExDuctArea	ACnfVal	0.050 [m²] 0.540 [ft²]
Extract air VAV duct shape ▶ Duct cross-sectional shape; Data entry by user triggers area calculation by controller; Direct entry uses user-entered area, not controller calculation. 1:Rectangular 2:Round 3:Flat oval 4:Direct entry	VavExDuctShape	MCnfVal	2:Round
Extract air VAV dimension A ▶ For rectangular duct: Width; for round duct: Diameter; for flat oval duct: Total width (major dimension) ; for Direct entry: Not used. 0...100 [cm], 0.0...39.4 [in]	VavExDmsnA	ACnfVal	20.0 [cm] 7.9 [in]
Extract air VAV dimension B ▶ For rectangular duct: Height; for round duct: Not used; for flat oval duct: Height (minor dimension); for Direct entry: Not used. 0...100 [cm], 0.0...39.4 [in]	VavExDmsnB	ACnfVal	20.0 [cm] 7.9 [in]
Extract air VAV flow coefficient ▶ The value used to calibrate span of airflowmeasurement; the value of calc flow coefficient is written to this object upon the Calibrate command. 0...2	VavExFlCoef	ACnfVal	0.780
Extract air VAV smoke control air volume flow setpoint ▶ Air flow setpoint if VavExDevMod=5. Air flow used in balancing if VavExBalMod = 3; balancer can use this as a manual airflowsetting.	VavExSpAflSmk	ACnfVal	50 [m³/h] 29.4 [ft³/min] 13.89 [l/s]
Extract air VAV maximum air volume flow for ventilation ▶ Maximum ventilation airflow setpoint for indoor air quality (IAQ) controller and for Rapid Ventilation; the airflowused for balancing when the Extract air VAV balancing mode = 1.	VavExAflMaxVnt	ACnfVal	100 [m³/h] 58.9 [ft³/min] 27.78 [l/s]
Extract air VAV minimum air volume flow for ventilation ▶ Minimum airflow setpoint for ventilation, whether fixed or controlled by indoor air quality (IAQ) controller; the airflowused for balancing when the Supply air VAV balancing mode = 2.	VavExAflMinVnt	ACnfVal	0 [m³/h] 0.0 [ft³/min] 0.00 [l/s]

Parameters

Description	Parameter	Default value
Failure mode for air volume flow sensor 1:Hold extract air 2:Open extract air 3:Close extract air ▶Also defines how the terminal responds if loss of network communication occurs. 1. Hold: Setpoint does not change 2. Close: Setpoint is set to the minimum flow of the mode the terminal was in during failure 3. Open: Setpoint is set to the maximum flow of the mode the terminal was in during failure	AirFlFailMod	1:Hold extract air
Switch-on point for differential pressure ▶ The differential pressure sensor signal value must be above this value or else zero is used.	SwiOnPtDiffP	0.2 [Pa] 0.001 [inWC]
Hysteresis for differential pressure ▶ Amount below SwiOnPtDiffP below which the pressure value used by the controller will be zero.	HysDiffP	0.1 [Pa] 0.0 [inWC]
Time constant for air volume flow ▶ The time constant for the attenuation filter on the air volume flow sensor. Increase the value to help stabilize fluctuating air volume flow sensor values, leaving at 0 disables the filter.	TiConAirFl	0 [s]
Switch delay for tracking method to air volume flow ▶ The airflow tracking signal that is sent to the room will automatically switch from setpoint to airflow when: Absolute Value (Relative Setpoint – Relative Air Flow) > SwiTolTckMthd, for a time longer than SwiTolTckMthd. SETTING TOLERANCE LEVEL (SwiTolTckMthd) TO 100% WILL NOT ALWAYS PREVENT TRACKING FROM SWITCHING FROM SETPOINT TO AIRFLOW.	SwiDlyTckMthd	60 [s]
Switch tolerance for tracking method to air volume flow ▶ The airflow tracking signal that is sent to the room will automatically switch from setpoint to airflow when: Absolute Value (Relative Setpoint – Relative Air Flow) > SwiTolTckMthd, for a time longer than SwiTolTckMthd. SETTING TOLERANCE LEVEL (SwiTolTckMthd) TO 100% WILL NOT ALWAYS PREVENT TRACKING FROM SWITCHING FROM SETPOINT TO AIRFLOW.	SwiTolTckMthd	5.0 [%]
Nominal air volume flow ▶ Optional. Maximum airflow capacity of the extract VAV box. Must be no larger than 1.2 times the value of extract maximum airflow for ventilation.	AirFlNom	0 [m³/h] 0.0 [ft³/min] 0.00 [l/s]
Control mode for air volume flow 0:Open-loop control 1:Closed-loop control	AirFlCtlMod	1:Closed-loop control
Minimum air velocity for control and venturi calibration	AirVMinCtlClb	1.778 [m/s] 350.0 [ft/min]
Time constant for relative air volume flow setpoint	TiConSpAflRel	2 [s]
Enable deviation calculation ▶ Enables the calculation of the deviation value (airflow setpoint minus airflow value) to be available for AHU fan static setpoint reset. See also section Air flow deviation signal. 0:No 1:Yes	EnDvnCal	1:Yes
Enable saturation calculation ▶ Enables the saturation signal calculation logic for AHU fan static pressure reset. See also section Saturation signal. Set to "Yes" to include this VAV in the AHU static fan pressure reset logic. Set to "No" to exclude undesired VAV from the AHU static fan pressure reset logic. An example of an undesired VAV would be a VAV that is part of a rogue zone. 0:No 1:Yes	EnStrtnCal	1:Yes
Saturation level ▶ The minimum VAV controller output before the saturation logic would send a starved signal (if other conditions are true; see Saturation signal section). In a calibrated venturi valve, the VAV controller output represents the venturi position deviation from the venturi calibration table. The saturation level is used for AHU static fan pressure reset to maximize energy efficiency while maintaining the pressure independence of the venturi valve. A higher value prioritizes energy efficiency while a lower value prevents insufficient airflow.	StrtnLvl	90 [%]
Air volume flow error limit ▶ The maximum allowable tolerance below airflow setpoint before the saturation logic would send a starved signal (if other conditions are true; see Saturation signal section). The airflow error limit is used to allow deviation below the airflow setpoint when the saturation level is exceeded. When set to 0, ignores calculation for AirFlErLm.	AirFlErLm	0 [%]
Switch-on delay saturation ▶ The time after the saturation conditions are met that the saturation signal to the AHU changes from False to True.	DlyOnStrtn	60 [s]
Switch-on point for air flow demand ▶ Airflow value (in percent of the largest configured max airflow) that defines the airflow demand switch-on point. The airflow setpoint VavExSpAirFl must equal or exceed this value before the terminal box begins to open.	SwiOnAirFlDmd	4 [%]
Hysteresis for air flow demand ▶ Hysteresis offset used to determine the airflow demand cutoff value. SwiOnAirFlDmd minus HysAirFlDmd = the airflow value that VavExSpAirFl needs to fall below before the damper closes.	HysAirFlDmd	2 [%]
Pressure unit ▶ Defined by selected engineering unit - do not change.	PUnit	[Pa] [inWC]
Air volume flow unit ▶ Defined by selected engineering unit – do not change.	AirFlUnit	[m³/h] [ft³/min] [l/s]
Air velocity unit ▶ Defined by selected engineering unit - do not change.	AirVUnit	[m/s] [ft/min]

Interface

Interface	Description	Type	Ref.	Owned by
VavExPos	Extract air VAV position	AO	◉	Room segment / Field device
VavExDiffP	Extract air VAV differential pressure	AI	◉	Room segment / Field device
VavExAirVEff	Extract air VAV effective air velocity	ACalcVal	●	-
VavExSpAirFl	Extract air VAV setpoint for air volume flow	APrcVal	●	-
TrndVavExSpAfl	Trend for extract air VAV setpoint for air volume flow	FtrSel	●	-
VavExSpAflRel	Extract air VAV setpoint for relative air volume flow	ACalcVal	●	-
VavExAirFl	Extract air VAV air volume flow	ACalcVal	●	-
TrndVavExAirFl	Trend for extract air VAV air volume flow	FtrSel	●	-
VavExAirFlRel	Extract air VAV relative air volume flow	ACalcVal	●	-
VavExAirFlDvn	Extract air VAV air volume flow deviation	ACalcVal	●	-
VavExAflStrtn	Extract air VAV air volume flow saturation 0:Satisfied 1:Starved	BCalcVal	●	-
VavExDevMod	Extract air VAV device mode 1:Off 2:Control mode 3:Maximum air volume flow 4:Minimum air volume flow 5:Smoke control air volume flow setpoint	MPrcVal	●	-
VavExAirFlCtr	Extract air VAV air flow controller	Controller	●	-
VavExAirFlReq	Extract air VAV air volume flow request	ACalcVal	●	-
VavExAvlVnt	Extract air VAV available for ventilation 0:No 1:Yes	BCalcVal	●	-
VavExAirFlTck	Extract air VAV air volume flow tracking	ACalcVal	●	-
VavTckMthd	VAV tracking method 1:Setpoint 2:Air volume flow	MCalcVal	●	-
VntrExClbCmd	Extract air venturi valve calibration command 1:Ready 2:Calibrate 3:Apply 4:Cancel	MTrgVal	●	-
VntrExClbSta	Extract air venturi valve calibration state 1:Initial 2:Failed calibration 3:Calibrated	MCalcVal	●	-
VavExFlCoefCal	Extract air VAV calculated flow coefficient	ACalcVal	●	-
VavExBalCmd	Extract air VAV balancing command 1:Ready 2:Balancing 3:Calibrate 4:Record 5:Balanced	MTrgVal	●	-
VavExSplyAir	Extract air VAV supply chain for air	GrpMbr	●	-
VavExBalSta	Extract air VAV balancing state 1:Initial 2:Balancing 3:Balanced	MCnfVal	●	-
VavExBalMod	Extract air VAV balancing mode 1:Maximum ventilation 2:Minimum ventilation 3:Smoke	MCnfVal	●	-
VavExAirFlHood	Extract air VAV air volume flow at hood	ACnfVal	●	-
VavExBalModRec	Extract air VAV recorded balancing mode 1:Maximum ventilation 2:Minimum ventilation 3:Smoke	MCnfVal	●	-
VavExAflHodRec	Extract air VAV recorded air volume flow at hood	ACnfVal	●	-
VavExFlCoefRec	Extract air VAV recorded flow coefficient	ACnfVal	●	-
VavExFlCoefIni	Extract air VAV initial flow coefficient	ACnfVal	●	-
VavExAirFlRec	Extract air VAV recorded air volume flow	ACnfVal	●	-
VavExPosRec	Extract air VAV recorded position	ACnfVal	●	-
VavExDuctArea	Extract air VAV duct area	ACnfVal	●	-
VavExDuctShape	Extract air VAV duct shape 1:Rectangular 2:Round 3:Flat oval 4:Direct entry	MCnfVal	●	-
VavExDmsnA	Extract air VAV dimension A	ACnfVal	●	-
VavExDmsnB	Extract air VAV dimension B	ACnfVal	●	-
VavExFlCoef	Extract air VAV flow coefficient	ACnfVal	●	-
VavExSpAflSmk	Extract air VAV smoke control air volume flow setpoint	ACnfVal	●	-
VavExAflMaxVnt	Extract air VAV maximum air volume flow for ventilation	ACnfVal	●	-
VavExAflMinVnt	Extract air VAV minimum air volume flow for ventilation	ACnfVal	●	-

Engineering and commissioning

Check for correct damper actuator installation. Actuator mis-wiring or improper installation is a major cause of common problems.

The relative airflow(VavExAirFlRel) is normalized as a percentage (0 - 100%) of VavExAirFl based on the nominal (rated) value for the box airflow(AirFlNom).