Distech Controls Smart-Sensor-VAV User Guide

Smart-Sensor-VAV Overview

156

Figure 7-1: Smart-Sensor-VAV

The Smart-Sensor-VAV will be referred to as the Smart-Sensor throughout this document.

The Smart-Sensor has a built-in thermistor for temperature sensing, a 2-line / 8-character LCD display and five push buttons. The Smart-Sensor measures the room temperature every few seconds, updates the value displayed on the LCD and sends the temperature to the controller.

The Smart-Sensor has a regular user mode for building occupants and a password-protected configuration mode that consists of a main configuration menu and 3 sub-menus (I/O display mode, flow configuration mode and flow calibration mode). The menu hierarchy and the options available in each menu and submenu are illustrated in Figure 7-2 .

VAV / VVT User Guide

Smart-Sensor-VAV User Guide

Figure 7-2: System Overview

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Startup and Errors

Normally, the first time that the Smart-Sensor is powered up, i.e. connected to a VAV/VVT from which it draws power, the text

SENSOR INIT…

will appear on the LCD screen. The

Smart-Sensor will also show this text after any power cycle of the VAV signifying that it is able to communicate with the VAV and that it is being initialized.

If there is a loss of communication between the Smart-Sensor and the VAV during regular operation, or if communication cannot be established on power up, the text

SENSOR COM FAIL will appear on the LCD display. The Smart-Sensor will periodically attempt to reestablish communication with the VAV and display the text

SENSOR RETRY!

If communication cannot be established, the LCD display will alternate between these two messages.

If a communications problem is encountered, examine the wiring between the

Smart-Sensor and the VAV. Verify the polarity and ensure that the wires are properly inserted into the wire terminals and that a wire length of 15 meters (50 feet) has not been exceeded.

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Smart-Sensor-VAV User Guide

Button Operation

Figure 7-3: Smart Sensor Push Buttons

The Smart-Sensor has five push buttons. A simple press-and-release of a button can be used to scroll through menu items or change displayed values one at a time. Alternatively, the UP or

DOWN button can be held to simulate repeated button presses, which is convenient when making changes to setpoints, adjusting the damper position, etc. In general, a single press of a button allows the user to view the status and an immediate second press allows the user to change the status.

VAV / VVT User Guide 159

User Mode

The user mode is meant to be accessible by building occupants so that they can view temperatures, adjust the setpoint and initiate an override. By default, the Smart-Sensor will display the room temperature.

Button Usage in User Mode

Not used in user mode.

Used to view the next available menu option.

Used to put the VAV into override mode. The occupancy state will temporarily change to BYPASS.

The DOWN button is used to view and decrease the setpoint.

Pressing the button once will display the setpoint. Pressing it a second time will decrease the temperature by 0.5 degrees. Holding down the button will decrease the value continuously until the button is released or the lower limit is reached.

The UP button is used to view and increase the setpoint. Pressing the button once will display the setpoint. Pressing it a second time will increase the temperature by 0.5 degrees. Holding down the button will increase the value continuously until the button is released or until the upper limit is reached.

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Smart-Sensor-VAV User Guide

User Mode – Display Text Definitions

Displayed Text Detailed Description

RoomTemp

Setpoint

Displays the current room temperature. The room temperature is the default display screen for the Smart-Sensor.

The temperature is read from the onboard temperature sensor and written to

nvoSpaceTemp

.

(SI Units: ºC / Imperial Units: ºF)

Displays the current midpoint. The setpoint can be modified by using the UP and DOWN arrows. The midpoint is the median value between the heating and cooling setpoints.

When the midpoint is changed, the heating and cooling setpoints will change by the same value.

Pressing the UP/DOWN buttons is like rotating the knob on regular wall-mounted sensors.

The diagram below illustrates the relation between the midpoint and the heating/cooling setpoints. In this example, the range between the heating and cooling setpoints is 2ºC and the midpoint is 21 ºC.

Field

Type

Read-

Only

Editable

If the HVAC mode is in cooling, the effective setpoint, i.e. the actual setpoint, will be the cooling setpoint. Similarly, if the HVAC mode is in heating, the effective setpoint will be the heating setpoint.

If the VAV has been setup for single room control only, then the setpoint that is entered using the Smart-Sensor (when in occupied, bypass or standby modes) is written to

nvoEffectSetpt

. However

nvoEffectSetpt

will equal

nviSetpoint

if

nviSetpoint

has been assigned a value, since it overrides all other setpoint values.

If the VAV is being used for two room control and the Smart-Sensor is associated with the first room, i.e. it provides SPACE_TEMP_ROOM1

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162

Cooling

Heating

OccState

Override

OutdoorTemp and is used to specify SETPOINT_ROOM1, then

nvoEffectSetpt

will equal the average of

SETPOINT_ROOM1 and

SETPOINT_ROOM2.

If there is no sensor providing a reading for

SETPOINT_ROOM2, then the controller averages SETPOINT_ROOM1 with the median of the heating and cooling setpoints stored in

nciSetPts.

(SI Units: ºC / Imperial Units: ºF)

If the HVAC mode is in cooling, the Smart-

Sensor will display the text

Cooling followed by the cooling setpoint, which is the effective setpoint at the time.

The HVAC mode is read from

nvoUnitStatus.

If the HVAC mode is in cooling, the Smart-

Sensor will display the text

Heating followed by the heating setpoint, which is the effective setpoint at the time.

The HVAC mode is read from

nvoUnitStatus.

Shows the current occupancy status.

The occupancy state is read from

nvoOccState

.

The text

Override will appear when the

Override button is pressed, and

nvoOccState

will be set to OC_BYPASS.

The controller will remain in bypass mode for the time period specified in

SCPTbypassTime

.

The outdoor temperature is only displayed if

nviOutdoorTemp

has been bound to a controller that can provide an outdoor temperature reading.

(SI Units: ºC / Imperial Units: ºF)

Read-

Only

Read-

Only

Read-

Only

Read-

Only

Read-

Only

The values that can be changed by the Smart-Sensor are read directly from the device in the

VAV Device Configuration

tool.

VAV / VVT User Guide

Smart-Sensor-VAV User Guide

Password-Protected Configuration Mode

The Smart-Sensor configuration mode is protected by a password and is hidden from building occupants. The configuration mode provides building personnel with a number of advanced configuration, monitoring and air balancing options as summarized in Figure 7-2.

Entering the Configuration Mode

To access the password-protected configuration mode, do the following:

1. Hold the and the buttons simultaneously for a few seconds. Release the buttons when you see the display screen text change to Login 5000.

2. Use the arrow keys to increase or decrease the displayed number until it matches the configured password. By default the password is 5001.

If the password has previously been changed and has been forgotten, examine the value of UCPTcomPassword or check the Password field in the

Error!

Reference source not found.

window.

3. Press the button to submit the password that was entered.

4. If the correct password has been entered, the Smart-Sensor will be in the

Srvc Pin

screen. If an incorrect password has been entered, the Smart-Sensor will display the text

Password

Failed

.

The Smart-Sensor will automatically exit the configuration mode 20 minutes after the last button press. To exit the configuration mode manually, hold the and the buttons simultaneously for a few seconds.

Button Usage in Configuration Mode

Used to access one of the three available submenus. This button will not have any effect unless the Smart-Sensor displays the text

Submenu

which indicates that it is possible to access a specific submenu.

Used to view the next available menu option.

Used like an "Enter" key on a keyboard. When this button is pressed, the value specified is sent to the controller.

Decreases the displayed parameter value.

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Increases the displayed parameter value.

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Configuration Mode – Display Text Definitions

Displayed Text Detailed Description Field

Type

Editable

Srvc Pin

SI Units

Temp Cal

VAV Mode

Submenu IO

State

Submenu Flow

Cfg

Submenu Flow

Cal

This menu is used to send a service pin message over the network. Setting the value to 1 and pressing the Override button is equivalent to pressing the service pin button on the controller.

This menu is used to specify the display units for temperature values. Setting the value to 0 will cause the Smart-Sensor to display temperatures in imperial units (°F & CFM). Setting the value to 1 will cause the Smart-Sensor to display SI units (°C & LPS).

The value is written to the field of

UCPTvavOptions

.

SmartSensorInSI

This menu is used to calibrate the temperature sensor. The arrow buttons can be used to increase or decrease the temperature calibration offset value by 0.1° per button press. The offset can be up to +/- 12.7°C or +/- 22.8°F. to The value is

UCPTcomInputCfg.Offset

. written

(SI Units: ºC / Imperial Units: ºF)

This menu is used to specify whether VAV or

VVT mode is being used. This menu can also be used to put a VAV controller into VVT mode.

Setting the value to 0 will put the controller into

VVT mode. Setting the value to 1 will put the controller into VAV mode.

The value is written to the

VVTmode

field of the

UCPTvavOptions

.

Pressing the Submenu button while in this menu will display the I/O state submenu.

Pressing the Submenu button while in this menu will display the flow configuration submenu.

Pressing the Submenu button while in this menu will display the flow calibration submenu.

Editable

Editable

Editable

Submenu

Link

Submenu

Link

Submenu

Link

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I/O State Configuration Submenu - Display Text Definitions

Displayed Text Detailed Description

Trm Load

Field

Type

Read-

Only

Input N

Output N

Displays the controller's terminal load. The terminal load value is read from

nvoTerminalLoad

.

Displays the value of hardware input N (where

N is between 1 and 4).

The value is read from

nvoHwInputN

(where

N is between 1 and 4).

Displays the value of hardware output N (where

N is between 1 and 6).

The value is read from the output value.

Read-

Only

Read-

Only

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Flow Configuration Submenu

Displayed Text Detailed Description

Min Flow

MinFlwHt

The minimum airflow that is to be maintained by the VAV box during normal operation. The flow setpoint only falls below the minimum flow if the Use zero flow as min flow while unoccupied or standby option is selected or if the flow setpoint is overridden.

Setting the minimum flow to zero means the damper can be fully closed in which case no fresh air will be supplied to the zone that the

VAV controls.

The value entered in this field is written to

SCPTminFlow

.

(SI Units: LPS / Imperial Units: CFM )

The minimum airflow that is to be maintained by the VAV when duct heating is turned ON unless it is overridden.

In occupied mode, the VAV controller generally controls the load by modulating the air flow between the Minimum flow and the

Maximum flow. The minimum flow heat value can be used when using an electric duct heater to prevent it from overheating.

When the minimum flow heat is lower than the

Minimum flow, the VAV controller uses the minimum flow heat as a low limit to protect an electric duct heater from overheating.

When the minimum flow heat is higher than the

Minimum flow, the VAV controller controls the load by modulating the air flow between the minimum flow heat and the Maximum flow on a call for duct heating.

In any case, when the air flow read by the VAV controller is 10% smaller than the minimum flow heat the duct heating is not allowed. The duct heating can restart if the air flow returns above 5% less than the minimum flow heat.

For a water duct coil, the minimum flow heat can be set to 0 to remove this protection.

Field

Type

Editable

Editable

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168

Max Flow

Nom Flow

DmpDrTm

Open CCW

The value entered in this field is written to

SCPTminFlowHeat

.

(SI Units: LPS / Imperial Units: CFM )

The maximum allowable airflow. The flow setpoint never exceeds this value unless overridden.

The value entered in this field is written to

SCPTmaxFlow

.

(SI Units: LPS / Imperial Units: CFM )

The expected airflow when the damper is fully open. It is also used to determine the next damper movement. If the nominal flow is unknown, it can be left at zero in which case the

Maximum flow will be used to determine the next damper movement.

The value entered in this field is written to

SCPTnomAirFlow

.

(SI Units: LPS / Imperial Units: CFM )

Used to specify the time that the damper will take to go from the fully closed position to the fully open position or vice-versa. Used only for built-in actuator.

The damper drive time can be set to between 45 seconds and 150 seconds. However, it is recommended to use the default value of 95 seconds.

The value entered in this field is written to

UCPTdamperDriveTime.

Used to specify the direction (Clockwise or

Counter Clockwise) in which the actuator rotates to open the damper. Set the value to 0 for clockwise or 1 for counter clockwise.

A binary value representing the damper direction is written to the

UCPTvavOptions.

DamperCCW

field of

Editable

Editable

Editable

Editable

VAV / VVT User Guide

Area

PitotFct

Smart-Sensor-VAV User Guide

This value is used to perform a calibration of the

VAV box without using a reference instrument, but by using the K Factor Calculator window.

The value entered in this field is written to

SCPTductArea

.

(SI Units: cm2 / Imperial Units: in2 )

Most VAV box / Pitot tube manufacturers create their Pitot tubes in a manner that it amplifies the differential pressure by a certain factor. Contact them to acquire the value of this factor if they have not provided it.

The Pitot factor is therefore a divider that is applied to the differential pressure reading that compensates for varying characteristics and flow effects in VAV box equipment and pickup probes, ie. the amplification factor. The Pitot

Factor must be entered along with the Area to ensure precise calibration.

The value entered in this field is written to

SCPTGainVAV

.

Editable

Editable

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170

Flow Calibration Submenu

Displayed Text Detailed Description

Flow

RunNrmOp

GotoMinF

GotoMaxF

The real-time air flow that is being supplied to the zone. The flow reading will only be available if the VAV has been calibrated.

The flow value is read from

nvoAirFlow

.

(SI Units: LPS / Imperial Units: CFM )

Terminates calibration mode and puts the VAV controller back into normal operation.

Calibration mode is activated as soon as a command is sent from the flow calibration submenu and it ends automatically when the

Smart-Sensor returns to user mode or the

RunNrmOp command is sent to the VAV.

While the controller is in calibration mode it will not respond to control demands.

Only use this button if the VAV is already calibrated. When this button is pressed, the VAV automatically maintains the Minimum Flow that was specified in the

Min Flow

screen of the

Flow Configuration Submenu , by adjusting the damper position. The VAV will dynamically compensate for changes in air pressure to ensure that the minimum airflow is maintained.

The VAV will continue to maintain the minimum airflow until the

RunNrmOp command is sent to the VAV or the passwordprotected menu is exited.

Only use this button if the VAV is already calibrated. When this button is pressed, the VAV automatically maintains the Maximum Flow that was specified in the

Max Flow

screen of the

Flow Configuration Submenu, by adjusting the damper position. The VAV will dynamically compensate for changes in air pressure to ensure that the maximum airflow is maintained.

The VAV will continue to maintain the minimum airflow until the

RunNrmOp command is sent to the VAV or the password- protected menu is exited.

Field

Type

Read

Only

Editable

Editable

Editable

VAV / VVT User Guide

Dmp Cmd

Dmp Pos

DifPress

CalLoVal

CalHiVal

CalToMin

CalToMax

VAV / VVT User Guide

Smart-Sensor-VAV User Guide

Moves the damper to the position that you specify in this screen. The damper can open between 0% (fully closed) and 100% (fully open).

The damper will remain at the position specified until the

RunNrmOp command is sent to the

VAV or the password-protected menu is exited.

Displays the current damper position (in %).

Editable

Read-

Only

Read-

Only

Displays the current differential pressure reading.

(SI Units: PA / Imperial Units: "WC)

When this option is used, the VAV can be calibrated based on an airflow that is close to the minimum flow that was specified in the

Min

Flow

screen of the Flow Configuration Submenu .

Adjust the damper until the flow hood (capture hood) reading is close to the minimum flow.

Enter the flow hood reading then press the

Override button. This is quicker than making micro adjustments to the damper as required when using the

CalToMin

option.

When this option is used, the VAV can be calibrated based on an airflow that is close to the maximum flow that was specified in the

Max

Flow

screen of the Flow Configuration Submenu .

Adjust the damper until the flow hood reading is close to the maximum flow. Enter the flow hood reading then press the Override button. This is quicker than making micro adjustments to the damper as required when using the

CalToMax option.

When this option is used, the VAV can be calibrated to the exact airflow that was specified in the

Min Flow

screen of the Flow Configuration

Submenu . Adjust the damper until the flow hood reading is equal to the minimum flow, change the onscreen value from 0 to 1 then press the

Override button.

When this option is used, the VAV can be calibrated to the exact airflow that was specified in the

Max Flow

screen of the Flow Configuration

Submenu.

Adjust the damper until the flow hood reading is equal to the maximum flow, change the onscreen value from 0 to 1 then press the

Editable

Editable

Editable

Editable

171

DoAutoCal

NOT CALIBRAT

Override button.

Performs an automatic calibration of the VAV.

Depending on whether or not the duct area has been entered in the

Area

screen of the Flow

Configuration Submenu, the VAV will use one of two automatic calibration methods. A detailed description of these methods is provided in the

K Factor/Pitot Factor Calibration section.

Displayed if the VAV has not been calibrated.

However if the VAV has been calibrated, it will show the calibration code that is stored in

nviCalibCode

.

Editable

Read-

Only

The values that can be changed by the Smart-Sensor are read directly from the device in the

VAV Device Configuration

window.

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