Temperature-Humidity-CO2 Monitor with Output Relay

ITEM # CDM77232

Temperature-Humidity-CO2 Monitor with Output Relay

Ideal for monitoring indoor air quality of houses, offices, classrooms, factories, hospitals and hotels. Includes relay for activating a ventilation system

Best For:



  • Measures ambient temperature, relative humidity (RH), dew point and wet bulb temperatures, and CO2 level
  • Backlit LCD displays ambient temperature, RH and CO2 level on separate readouts
  • Uses stable non-dispersive infrared (NDIR) sensor to measure CO2
  • Calculates, periodically updates and displays 8-hr. time-weighted average (TWA) of CO2 exposure and 15-minute short-term exposure limit (STEL)
  • Adjustable Hi and Lo audible/visual CO2 alarm levels
  • Relay activates/cancels output signal when CO2 level exceeds Hi alarm level/falls below Lo alarm level
  • Min/Max memory + data hold
  • RS-232 output jack; optional ASFTKIT PC interface/data logging kit includes RS-232 to USB adaptor
  • 33% and 75% HR33 and HR75 reference salts are available to calibrate relative humidity (RH) measurement in the field
  • Auto power off (can be disabled for calibration)
  • Wall or desktop mount


  • Ambient temperature measurement range/resolution: 14 to 140F (-10 to 60C)/0.1
  • Ambient temperature measurement accuracy: 0.9F (0.6C)
  • RH measurement range/resolution: 0 to 99.9%RH/0.1%
  • RH measurement accuracy: 3% from 10 to 90%RH; 5% elsewhere
  • CO2 measurement range/resolution: 0 to 5000ppm/1 ppm
  • CO2 measurement accuracy: (30 ppm + 5% of reading)
  • CO2 calibration level: 400ppm
  • CO2 alarm level adjustment range: 100 to 9900 ppm
  • CO2 alarm relay outputs: 5V (activated); 0V (cancelled)
  • Warmup time: 30 seconds
  • Response times: 30 seconds for temperature and CO2; 30 minutes for RH
  • Auto power off triggering time: 20 minutes of front-panel inactivity
  • Operating temperature: 32 to 122F (0 to 50C) @ <80% RH
  • Weight: 14 oz. (397g)
  • Power source: AC adaptor (included)


  • AC adaptor
  • Users manual
  • 1-year limited warranty


  • 6.88 x 5.63 x 2.38 in. (174.75 x 143 x 60.45mm)