General Tools and Instruments DCFM8906 v.1 User Manual

Page 14

make a performance measurement inside an HVAC/R duct.
A multi-point average air speed reading is inherently more
representative of a system’s output than any single-point
reading, whether in the center of a duct or near one of its sides.

To make and store the multiple measurements, use the
HOLD and MIN/MAX REC SINGLE-POINT buttons. Start by
positioning the meter’s vanes at the first point to be
measured. When the reading is stable, press the HOLD
button. This sounds the beeper, makes Hold appear on the
top line of the upper display and freezes both readouts—the
normal consequences of pressing the HOLD button.

Now press the MIN/MAX REC SINGLE-POINT button. The
beeper will sound and the temperature reading in the lower
display will temporarily change to the number 1 to signify that
this is the first of several air speed readings stored (Fig. 5).

Fig. 5. The brief display indicating storage of a 325 ft/m

air speed reading at point 1