General Tools and Instruments CIH20DL - Manual (Page 3)

INTRODUCTION
Thank you for purchasing General Tools & Instruments’ CIH20DL Data Logging Hot Wire
Anemometer with CFM/CMM and 8:1 IR Thermometer. Please read this user’s manual
carefully and thoroughly before using the instrument.
The CIH20DL is a professional-grade, handheld hot wire anemometer that can not only
measure the speed of air exiting the grille or register of an HVAC/R system or blower or fan,
but also convert those readings to airflow volume measurements in units of CFM (cubic feet
per minute or ft 3 /min) or CMM (cubic meters per minute or m 3 /min). The conversions are
possible because the meter allows the user to enter the free area dimensions of grilles and
output ductwork.
The instrument can also measure the temperature of cooling or heating air, as well as
surface temperatures. Air temperatures from 32° to 158°F (0° to 70°C) are measured by a
thermistor located next to the hot wire sensor at the end of a 6 ft. (1.8m) long telescoping
metal probe and cable. Surface temperatures from -25° to 999°F (-32° to 538°C) are
measured by an integral infrared (IR) thermometer with a distance-to-spot (D:S) ratio of 8:1.
A hot wire anemometer measures air speed in the following way. When the instrument is
powered on, direct current is passed through its hot wire sensor for about 15 seconds. After
the sensor has been warmed to a constant temperature, the instrument detects how much
current is required to maintain that temperature as wind passing across the sensor acts to
cool it. The amount of current required is directly proportional to the square of the wind
speed.
Hot wire anemometers are as accurate as vane anemometers, but hot wire units are better
able to measure very slow air currents because they have no moving parts and therefore
no inertia. For example, the CIH20DL can measure air speeds as low as 2 ft/min. A typical
vane anemometer of comparable quality and accuracy cannot measure air speeds lower
than 80 ft/min.
The CIH20DL has a large backlit display with three readouts: one shows air speed or airflow
volume, another is for IR temperature, and the third is dedicated to air temperature.
Normally, each of these readouts shows real-time measurements, which can be held (frozen)
and read later to enable work in dark areas. End users can opt to have the readouts show
maximum, minimum or average measurements instead. End users also can store up to nine
sets of the three readings (air speed or airflow volume, air temperature and IR temperature)
in an internal nonvolatile memory and recall them at any time in chronological order.
In addition to storing the nine sets of readings, the CIH20DL also can capture—over long
periods of time—and time-stamp up to 20,000 air speed/airflow volume, air temperature
and surface temperature measurements at a user-selected sampling rate from 5 seconds
to 1 hour. These time-stamped readings, called data logs, can be copied to a PC running
Windows ® 7, Windows ® Vista or Windows ® XP via an included USB cable. Once in the
computer, the logs can be displayed as graphs or tables, formats that make it easy to spot
trends or unexpected excursions in readings.
Windows ® 7, Windows ® Vista and Windows ® XP are registered trademarks of Microsoft Corporation.
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