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Page 6
To confirm the temperature calibration, press the
SET
button (do not hold), and the humidity
will begin flashing.
2.
Humidity Calibration
. To increase the humidity to match your calibration source, press the
+
button. To increase rapidly, press and hold the
+
button. To decrease the humidity, press
the
ALARM
button. To decrease rapidly, press and hold the
ALARM
button.
To confirm the humidity calibration and return to normal mode, press the
SET
button (do not
hold).
Temperature Calibration Discussion
:
Temperature errors can occur when a sensor is placed too
close to a heat source (such as a building structure, the ground or trees).
To calibrate temperature, we recommend a mercury or red spirit (fluid) thermometer. Bi-metal (dial)
and other digital thermometers are not a good source and have their own margin of error. Using a local
weather station in your area is also a poor source due to changes in location, timing (airport weather
stations are only updated once per hour) and possible calibration errors (many official weather stations
are not properly installed and calibrated).
Place the sensor in a shaded, controlled environment next to the fluid thermometer, and allow the
sensor to stabilize for 24 hours. Compare this temperature to the fluid thermometer and adjust the
console to match the fluid thermometer.
Humidity Calibration Discussion
: Humidity is a difficult parameter to measure electronically
and drifts over time due to contamination. In addition, location has an adverse affect on humidity
readings (installation over dirt vs. lawn for example).
Official stations recalibrate or replace humidity sensors on a yearly basis. Due to manufacturing
tolerances, the humidity is accurate to ± 5%. To improve this accuracy, the indoor and outdoor
humidity can be calibrated using an accurate source, such as a sling psychrometer or one step
humidpak calibration kits (reference Section 7).
3
Heat Index Safety Discussion
The following section is courtesy of the United States National Weather Service Office of Climate,
Water and Weather Services.
The Heat Index, sometimes referred to as the apparent temperature is given in degrees Fahrenheit. The
Heat Index is a measure of how hot it really feels when relative humidity is factored with the actual air
temperature.
To find the Heat Index temperature, look at the Heat Index chart below. As an example, if the air
temperature is 96°F and the relative humidity is 65%, the heat index (how hot it feels) is 121°F.
IMPORTANT
: Since heat index values were devised for shady, light wind conditions, exposure to
full sunshine can increase heat index values by up to 15°F. Also, strong winds, particularly with very
hot, dry air, can be extremely hazardous.
The Heat Index Chart shaded zone above 105°F shows a level that may cause increasingly severe heat
disorders with continued exposure or physical activity.
