Indoor Air Quality (IAQ) Sensor Connection & Setup
(Applicable to units with SE Boards rev 3.3 and greater)
Introduction
An indoor air quality (IAQ) sensor monitors carbon dioxide (CO2) levels in the space and can put the unit into demand ventilation to lower the CO2 levels back to acceptable limits.
Demand Ventilation Operation
The control must be in occupied status with the indoor fan operating. If the demand ventilation mode (DVent-Mode) of operation is set to enabled and the operational indoor CO2 level (OprIAQ) is greater than the demand ventilation setpoint (DVentIAQ-SP) +100 ppm, the current operating minimum position increases as follows:
- With a CO2 level between the demand ventilation setpoint +101 ppm and +200 ppm, the operating minimum position increases 1% per minute.
- With a CO2 level greater than the demand ventilation setpoint +200 ppm, the operating minimum position increases 2% per minute.
When the CO2 levels drop to equivalent values below the demand ventilation setpoint, the current operating minimum position decreases at the same rates. While in a demand ventilation mode, if the supply air temperature drops below 49°F, the economizer outside air dampers close until the supply air temperature rises above 49°F but does not go below the current economizer operating minimum position. The economizer then modulates to control the supply air temperature at 50°F.
Wiring the IAQ Sensor
The IAQ sensor connects to the unit's economizer module. Under analog inputs at the bottom of the board, you will find 24V, IAQ, and COM. These connect to terminals 1, 2, and 8 on the IAQ sensor subbase.
Specific connections:
- 24V on the economizer control connects to terminal 1 on the IAQ sensor.
- IAQ on the economizer control connects to terminal 8 on the IAQ sensor.
- COM on the economizer control connects to terminal 2 on the IAQ sensor, and a jumper needs to be installed between terminals 2 and 7 on the sensor subbase.
| Economizer Control Terminal | Wire Color | IAQ Sensor Terminal | IAQ Sensor Label |
|---|---|---|---|
| 24V | Red | 1 | 24V |
| IAQ Signal | White | 8 | IAQ Signal |
| COM | Black | 2 | IAQ Common |
Confirming the Sensor Setup
The economizer board accepts a 0-10 VDC signal. The J7 (CO2) pin selection on the back of the sensor must be set for 0-10 VDC.
The sensor board features a small screen displaying status information, an arrow or 'Cursor' for navigation, and a joystick control. The screen can show 'Status' and 'Alarms'. The joystick has directional inputs (Up, Down, Left, Right) and an 'Enter' button. Options like 'TEMP', 'RH', and 'CO2' are selectable, and a 'J1' pin selection is present on the back.
Enable Demand Ventilation
In order for Demand Ventilation to be operational, it must be enabled. From the home screen, scroll down using the joystick until the "Status" menu directory is visible at the top of the screen and "Alarms" is visible at the bottom. The arrow or "Cursor" on the left of the screen will be pointing at one of the two selections. The cursor is used to select the menu directory you will enter when you press the enter button. The position of the cursor is changed by moving the joystick up or down.
Configuration Steps:
- Scroll down until the "Cursor" points to Details and press [Enter Button].
- Then scroll down to "DVent" and press [Enter Button].
- Then scroll down to DVent-Mode and press [Enter Button].
- Then push joystick [Move Right] until "Controlled by IAQ" is displayed and press [Enter Button].
Setting Maximum Economizer Position:
- Then scroll down to DVentMaxEconPos. This is the maximum amount the damper position will open during demand ventilation. The factory default setting is 50%. This setting can be changed to meet specific demands.
Setting Demand Ventilation Setpoint:
- Scroll down to DVentIAQ-Sp. The default setpoint is 1000 Parts Per Million (ppm). Press [Enter Button] to see the value.
- If a change is necessary, the revision of the board will determine how it is changed.
- On boards with rev 3.3 thru 4.1, push the joystick [Left/Right] to raise or lower the value and press [Enter Button].
- On boards with rev 4.2 & higher, press [Enter Button], then move left or right with the joystick to select the specific digit(s) that need to change. You will then increase or decrease the setting by moving the joystick [Up/Down].
- Once the desired value is entered, press [Enter Button], then press [Enter Button] a second time to confirm. DVent Mode is now operational.
