Comfort Chek
400 Operation Manual
1509-9000 Rev 4
7
4. OPERATION
4.1. Power On/Off
Press the SET button to switch instrument on. At power up, it emits a short beep and
performs a 30-second countdown while the instrument warms up. It then enters
normal operating mode displaying real time CO
2
, temperature, and RH readings. To
switch the instrument off, press the SET button.
Figure 4-1. Warm-up Countdown
Figure 4-2. Normal Operating Mode
NOTE:
For the purpose of saving battery life, the unit will switch itself off after 20
minutes of operation. For continuous operation, switch the unit on using both SET and
HOLD buttons together.
4.2. Taking Measurements
The instrument starts taking measurements upon power up and updates information
on the LCD every second. When the environment to be monitored changes (example:
from high temperature to low temperature), it takes 30 seconds to update the CO
2
reading and 30 minutes to update the RH reading.
NOTE
: Do not hold the instrument close to your face because your exhalation will
affect the CO
2
, temperature and RH readings.
Press DP/WBT (down arrow) button to switch between the three different
temperature units of measure. The lower left portion of the LCD will cycle from air
temperature to dew point temperature to wet bulb temperature.
Figure 4-3. Dew Point Temperature
Figure 4-4. Wet Bulb Temperature
4.3. Back Light
Hold down MODE for more than 1 second to activate or cancel the back light function.