Sensors That Make Buildings Smart!
AirTest CO2 Control Brochure
The Free AirTest CO2 Ventilation Calculator Tool
Suggested CO2 Sequence Of Operation
CO2 In School Classrooms
CO2 Reference Library
Reduce Over Ventilation And
Energy Waste with CO2
Background on CO2 for Ventilation Control
Explanation of CO2 sensor self calibration for TR9220 and TR9290
Why" Length Matters" for CO2 meansurement (TR9220, TR9290)
Technical background on CO2 DCV
Using CO2 to measure combustion fumes
Using CO2 to control smoking in hospitality venues
Assessing buildings for CO2 retrofit
CO & energy savings case studies
AirTest CO2 energy analysis software
AirTest Training Center

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Model TR9220 Model TR9220-L TR9223 Model 9223-L
Wall Mount without Display Wall Mount with Display Splash Resistant Case Splash Resistant Case with Display


  • building control
  • schools
  • meeting rooms
  • theaters / conference areas


Key Features

  • lifetime self calibration (15 years)
  • active temperature sensor
  • jumper configuration for 0-10 V, 2-10 V, 4-20mA outputs for CO2 & Temp
  • outputs scalable via PC software interface
  • utilizes patented gold plated optical sensing element with 4.7 inch path length
  • Now also available with LonWorks® communication capability as a LonMark® Certified product.



  • display or no-display
  • relay for CO2
  • modbus plug-in option
  • RS485 plug-in option
  • Lonworks® version available

Model TR9220

CO2 & Temp

  • Measures: 0-2,000 CO2
  • CO2 Accuracy: ± 30 ppm + 3% of reading
  • Temp Range: 32-122 F (0-50 C)
  • Power: 24 VAC
  • CO2 Output: 0-10 V, 2-10 V, 4-20 mA
  • Temp Output: 0-10 V, 2-10 V, 4-20 mA
  • ISO-9001 manufactured for quality

Datasheet Manual (TBA)
LonMark® Certified Catalog Listing
LonWorks XIF/DRF Files



  • TR9220 - Wall Mount without Display
  • TR9220-L - Wall Mount with Display
  • TR9221 - Duct Probe
  • TR9221-L - Duct Probe with Display
  • TR9223 - Splash Resistant Case
  • TR9223-L - Splash Resistant Case with Display
Published: February 16, 2004 Last Updated: September 25, 2008