Comfort Chek400

Comfort Chek® 400

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An entry-level IAQ monitor
  • Simultaneously displays CO2, temperature and relative humidity for easily assessing indoor air quality
  • Selectable CO2 alarm level plus display options for CO2 and temperature
  • All kits include hard carrying case for safe storage and transportation

The Comfort Chek® 400 is an easy and affordable way to measure the three main parameters of indoor air quality – CO2, temperature and relative humidity. Power can come from either 4 AA replaceable batteries or the supplied wall adapter for continuous operation, making the Comfort Chek® 400 ideal for monitoring air quality in offices, schools, hotels or other public spaces.

A large, backlit LCD shows all three readings simultaneously, with advanced features such as a CO2 level alarm, selectable MIN/MAX/STEL/TWA values for CO2 and air/dew point/wet bulb values for temperature. The Comfort Chek® 400 comes in a sturdy, hard-shell carrying case to protect your investment and is covered by a 2 year warranty.




Temperature (ambient)

Relative humidity


0 to 5000ppm

14 to 140 °F (-10 to 60 °C)

0 to 99.9% (non-condensing)


LCD with backlight, shows all 3 readings simultaneously


4x AA batteries or via included wall adapter

Run Time

20 to 24 hours typical, using alkaline batteries (continuous using wall adapter)

Size (H x W x D)

6.6 x 2.8 x 1.3 in. (16.8 x 7.1 x 3.3 cm)


7.1 oz. (200 g) including batteries

Operating Conditions

32 to 122 °F (0 to 50 °C), 0 to 95% RH (non-condensing), 1 ATM ± 10%

Warm-up Time

30 seconds


CE mark


2 years