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Home > Carbon Dioxide (CO2) > CHTOL Series (CO2/RH/Temp) Outdoor Sensor

CHTOL Series (CO2/RH/Temp) Outdoor Sensor

  • LCD with field calibration menu
  • 2000/5000 ppm CO2, 2% RH
  • Integrated set-point relay
  • Field replaceable NDIR CO2 element


  • Outdoor CO2, humidity and temperature measurement for building control
  • Economizer control
  • Facilitates compliance with ASHRAE 62.1 standard for air quality


The CHTOL Series is designed to be mounted on the building exterior to provide outside CO2, relative humidity and temperature measurement all from one outdoor rated enclosure. The standard LCD, gasketed lid and field replaceable CO2 element make initial installation and future service a breeze. The CHTOL can also be customized with optional RTDs or thermistors for further added flexibility when ordering.

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CO2, humidity, and temperature all in one device...fewer units to buy and install

  • LCD display for easy set up of all parameters
  • Options for complete control including set-point
  • 0-5/10V outputs standard. Thermistors optional

High performance NDIR CO2 with set-point relay

  • Non-dispersive infrared sensing element (NDIR) 
  • Selectable auto-calibration mode returns sensor to baseline values
  • Field replaceable CO2 sensor
  • 2000 or 5000 ppm scale

2% RH Accuracy

  • On-board temperature compensation for rH eliminates temp coefficient errors achieving excellent measurement accuracy, high repeatability and offset stability. 


  • Outdoor rated enclosure includes gasketed lid and solar shield with sintered filter for RH element
  • Industry leading 7-year limited warranty/ 2-year RH element, 3-year CO2 element limited warranties