AAON Orion ASM01824 Quick start guide
I2C CO2Sensor
Technical Guide
TABLE OF CONTENTS
SENSOR OVERVIEW ....................................................................................................................................... 3
Features .......................................................................................................................................................................................3
Environmental Requirements .......................................................................................................................................................3
WALL-MOUNTED SPACE CO2SENSOR WIRING TO HVAC UNIT CONTROLLER ........................................ 4
DUCT-MOUNTED CO2SENSOR MOUNTING & WIRING TO HVAC UNIT CONTROLLER............................. 5
DUCT-MOUNTED CO2SENSOR INSTALLATION............................................................................................ 6
TROUBLESHOOTING...................................................................................................................................... 8
Setting The Sensor Address Switch .............................................................................................................................................8
Using LEDs to Troubleshoot ........................................................................................................................................................8
Altitude Correction ........................................................................................................................................................................8
TB1 Terminal Block (CO2 Reading) ..............................................................................................................................................9
APPENDIX...................................................................................................................................................... 10
Mounting Plate Dimensions........................................................................................................................................................10
AAON, Inc.
2425 South Yukon Ave.
Tulsa, OK 74107-2728
www.aaon.com
Factory Technical Support Phone: 918-382-6450
Controls Support Phone: 866-918-1100
AAON P/N: G042470, Rev. 01F
Copyright August 2019 AAON, Inc.
AAON® is a registered trademark of AAON, Inc., Tulsa, OK.
AAON assumes no responsibility for errors or omissions.
This document is subject to change without notice.
PART NUMBER TABLE
PART DESCRIPTION AAON P/N
Wall-Mounted I2C CO2 Space Sensor ASM01824
Duct-Mounted I2C CO2 Sensor (RA or SA) ASM01826
I2C Digital Room Sensor Temp Only ASM01817
I2C Digital Room Sensor Temp & Humidity ASM01818
Mounting Plate G026490
VCM-X E-BUS Controller ASM01702
This manual is also available for download from our
website—www.aaon.com/controlsmanuals—under
Previous Generation Sensors, where you can always
find the latest literature updates.
Technical Guide
CO2 SENSOR
3
Overview
The I2C Wall-Mounted Space CO2 Sensor (ASM01824) is used for moni-
toring room CO2 levels and is designed for permanent wall mounting in
the conditioned space. It connects to the VCM-X E-BUS Controller using
TSDRSC modular prefabricated cable with RJ-45 connectors. It can be
daisy-chained with the I2C Digital Room Sensor or wired separately
from the Orion Standard Room Temperature Sensor for applications
requiring both a room CO2 sensor and room temperature sensor. See
Figure 1 for dimensions.
The I2C Duct-Mounted CO2 Sensor (ASM01826) is comprised of the
ASM01824 CO2 Sensor and the AAON Aspiration Box Assembly. It
is used for sensing the current CO2 level in the HVAC unit’s return air
stream. It is designed to be mounted in the return air of the HVAC unit
and uses its integral aspiration box to sample the CO2 level in the duct.
Some typical applications are:
Controlling ventilation in a building where the occupancy
varies frequently
Controlling ventilation to ensure excess outdoor air is not
causing energy waste
Ensuring good air distribution throughout building zones
Demand Control Ventilation
Sensor Overview
Features
The CO2 Sensor provides the following:
Uses the patented dual beam Non-Dispersive Infrared™
(NDIR) technology
A very accurate and stable sensor guaranteed to maintain
its accuracy due to infrared self-calibration feature of sensor
Sensor accuracy of +/- 50 ppm @ 1000 ppm or 2% of the
measured value
Annual drift of +/- 2 ppm per year
Measurement range of 0 to 2000 ppm
LED under front cover shows active CO2 sensing
Addressable based on function within the system Figure 1: Wall-Mounted CO2 Sensor Dimensions
Environmental Requirements
The CO2 Sensor needs to be installed in an environment that can main-
tain a temperature range between 14°F and 122°F and a humidity range
between 5% and 95% RH (non-condensing).
CO2 SENSOR
Technical Guide
4
Figure 2: Wall Mounted Space CO2 Sensor & Digital Room Sensor Wiring for VCM-X E-BUS Controller
Wall-Mounted Space CO2Sensor Wiring to HVAC Unit Controller
Wall-Mounted CO2Sensor
The Wall-Mounted Space CO2 Sensor utilizes a sub-base mounting plate
with a modular phone jack providing quick and easy mounting and wir-
ing. The wall-mounted sensor’s sub-base is compatible with standard
junction boxes. A locking screw secures the assembly to the wall.
Optional Mounting Plate
Included with the CO2 Sensor is a mounting plate that can be
used, if necessary, to cover the sensor sheet rock opening. This
mounting plate screws onto the back of the housing base. The
mounting plate is then mounted and covers the recessed space
in the wall. A locking screw secures the sensor to the wall. See
Figure 8, page 10 for mounting plate dimensions.
Wiring to the HVAC Unit Controller
The Wall-Mounted Space CO2 Sensor connects to the VCM-X E-BUS
Controller with the TSDRSC modular cable. It can be daisy-chained
with the Digital Room Sensor or used separately from a Standard Room
Temperature Sensor for applications requiring both a room CO2 sensor
and room temperature sensor. Refer to Figure 2 for instructions.
Technical Guide
CO2 SENSOR
5
Figure 3: Duct-Mounted CO2 Sensor & Digital Room Sensor Wiring for VCM-X E-BUS Controller
Duct-Mounted CO2Sensor Wiring to HVAC Unit Controller
Duct-Mounted CO2Sensor
The ASM01826 is comprised of the ASM01824 CO2 Sensor and the
AAON Aspiration Box Assembly. See Figure 3, below and Figures 4
& 5, pages 6 & 7 for mounting, wiring, and installation details.
The Duct-Mounted CO2 Sensor is used for sensing the current CO2 level
in the HVAC unit’s return air stream. The return air sensing use of this
sensor is applied when you want an average CO2 reading in the area
served by the HVAC unit or when you don’t want a wall mounted CO2
Sensor due to sensor tampering concerns in the space.
The OE256-02 Duct Mounted CO2 Sensor is designed to be mounted
in the return air duct of the HVAC unit and uses its integral aspiration
box to sample the CO2 level in the duct. Its address switch is factory set
to address “1” which is for space or return air sensing applications and
does not need to be changed for this application.
CO2 SENSOR
Technical Guide
6
Duct-Mounted CO2Sensor Installation
Duct-Mounted CO2Sensor Installation
To install the Duct-Mounted CO2 Sensor, please follow the instructions
below. See Figures 4 & 5 for detailed illustrations of the Duct-Mount-
ed CO2 Sensor and its components.
STEP 1: Find the general location on the side of the Return Air
Duct where you want to mount the CO2 Sensor. Be sure to locate
the box with the airfl ow in the proper direction per the airfl ow
label. Using the Aspiration Box as a template, draw around it with
a pencil on the duct. Locate the center of the box you have drawn
and mark it. Using a 1 1/4” hole saw, drill a hole in the duct wall
using the center you have just drawn as the drilling point. Insert
the aspiration tube into the hole in the duct and mount the Aspira-
tion Box to the Duct using a power screwdriver to secure the (4)
mounting feet to the Duct wall using the (4) supplied sheet metal
screws.
STEP 2: Remove the Aspiration Box cover from the Aspiration
Box base by loosening the (4) screws that secure it with a Phillips
screwdriver. Using the Phillips screwdriver, loosen the (2) conduit
clamp screws on the conduit clamp assembly located on the side
of the Aspiration Box enough to allow the insertion of the RJ-45
male cable connector(s) and cable(s) through the cable clamp
opening and into the Aspiration Box using the appropriate length
of pre-fabricated TSDRSC cable(s) as required by your applica-
tion.
STEP 3: Remove the CO2 Sensor cover with circuit board by
using the included Allen wrench to loosen the set screw located
at the bottom edge of the CO2 Sensor assembly and pulling the
Sensor cover with circuit board apart from the Sensor base. Route
the RJ-45 male plug(s) and cable(s) under the Sensor base and
through the rectangular clearance opening in the Sensor base and
then plug the RJ-45 male cable connector(s) into the RJ-45 female
connector(s) on the back of the Sensor circuit board which is at-
tached to the Sensor cover.
STEP 4: The address switch is factory set to “1” which is cor-
rect for Space CO2 Sensor applications or Return Air CO2 Sensor
applications. If you have a custom coded application and need to
change the address switch, see page 8 for instructions.
STEP 5: After setting the address switch (if required), re-install
the Sensor cover with circuit board to the Sensor base using the
supplied Allen wrench and set screw and re-install the Aspira-
tion Box cover in reverse fashion from how you disassembled it
previously.
STEP 6: Tighten the conduit clamp screws down until the
conduit clamp is gripping the Sensor cable(s) snuggly. Do not
over-tighten the clamp screws as this could damage the cable(s).
Figure 4: CO2 Sensor Components and Wiring
Technical Guide
CO2 SENSOR
7
Figure 5: Mounting and Cable Installation for Duct-Mounted CO2 Sensor
Duct-Mounted CO2Sensor Installation
CO2 SENSOR
Technical Guide
8
Troubleshooting
Setting the Sensor Address Switch
LED ON/OFF Push-Button Operation for Setting
Address
The LED ON/OFF Push-Button is used to set the CO2 Sensor’s address.
The LED ON/OFF Push-Button is located on the Sensor’s board and is
only visible by removing the back cover. See location in Figure 6. The
default addresses are as follows:
• Space or Return CO2 Sensor = Address 1 (Default)
• Address 2 is reserved.
• Open addresses for Custom Applications = Addresses 3-10
To set the address, follow these instructions:
1. Power up the VCM-X Controller that the Sensor is plugged
into.
2. Press the LED ON/OFF Push-Button for 5 seconds until the
LEDs turn off .
3. Then press the push-button the number of times that repre-
sents the address. Press once for address 1, press twice for
address 2, etc.
4. The address range can be set to 1 (default) and from 3 to 10.
5. To verify that the correct address has been entered, refer to
the STATUS LED information below.
The board address is stored in nonvolatile memory. Once the address is
set, the address will be saved after loss of power.
Using LEDs to Troubleshoot
LEDs are available for troubleshooting the CO2 Sensor. The Front LED
is visible through the front cover of the CO2 Sensor. See Figure 7 for
location. The other LEDs are located on the Sensor’s board and are only
visible by removing the back cover. See Figure 6 for locations.
LED ON/OFF Push-Button
This button is located on the CO2 Sensor’s board. See Figure 6. This
button is initially set for “LEDs OFF.” Push this button to enable/disable
the LEDs. Pushing this button ON will make the Front LED light up.
This LED is also used for setting the address.
Front LED
When the LEDs are turned on, a green LED will be visible through the
front plastic cover of the CO2 sensor. See Figure 7. The Front LED
will blink whenever a CO2 sample is taken. A sample is taken every
30 seconds.
STATUS LED
Initially, the STATUS LED blinks fast for 30 seconds. It then stays on
and blinks the board address whenever a CO2 sample is taken. A CO2
sample is taken once every 30 seconds.
COMM LED
The COMM LED blinks on whenever communications are sensed.
Altitude Correction
Altitude correction can be confi gured using one of our operator inter-
faces. The altitude can be confi gured at a value of 0-15,000 feet. The
default is 500 feet.
Technical Guide
CO2 SENSOR
9
Figure 6: LED ON/OFF Button and Board LEDs
Figure 7: CO2 Sensor’s Front LED
TB1 Terminal Block (CO2 Reading)
The TB1 terminal block should only be used to test the sensor when the
sensor cable is plugged into the controller and the sensor and controller
are powered up. Directions: Set the meter for DC volts and connect the
GND probe to the GND terminal and the + probe to the CO2 0-5 terminal.
Look at the output voltage and record it. Multiply the voltage times 400.
The value should match the CO2 as read on the System Manager TS,
Modular System Manager, Modular Service Tool, or Prism. If the signal
doesn’t match the sensor reading, contact AAON Controls Support.
Troubleshooting
CO2 SENSOR
Technical Guide
10
Appendix - Mounting Plate Dimensions
Optional Mounting Plate
Included with the CO2 Room Sensor is a mounting plate that can
be used, if necessary, to cover the sensor sheet rock opening. This
mounting plate screws onto the back of the housing base. The
mounting plate is then mounted and covers the recessed space
in the wall. A locking screw secures the sensor to the wall. See
Figure 8, below for dimensions.
1.638
1.810
0.882
1.407
1.842
0.733
2.110
2.920
0.810
R0.220
3.275
0.060
0.160
5.037
3.278
3.766
4.153
Figure 8: Mounting Plate Dimensions
Technical Guide
CO2 SENSOR
11
Notes
2425 South Yukon Ave • Tulsa, OK • 74107-2728
Ph: (918) 583-2266 • Fax: (918) 583-6094
AAON P/N: G042470, Rev. 01F
Printed in the USA • © August 2019 AAON, Inc. • All Rights Reserved
AAON Factory Technical Support: 918-382-6450
techsuppor[email protected]
AAON Controls Support: 866-918-1100
Monday through Friday, 7:00 AM to 5:00 PM
central standard time.
NOTE: Before calling Technical Support, please have the
model and serial number of the unit available.
PARTS: For replacement parts please contact your local
AAON Representative.
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