Chapter 5
Pressure/Air Handler Flow Mode
-
Insert a static pressure probe into the supply plenum, or in a main supply trunk line a few feet away from the
supply plenum. Make sure the static pressure probe is pointing into the air flow created by the air handler fan.
-
Connect a piece of tubing to the static pressure probe. Connect the other end of the tubing to the
Channel A
Input
tap on the DG-700. The
Channel A Reference
tap should be connected to the inside of the building, or it
can be connected to an unconditioned zone containing the air handler provided that the zone remains at the same
pressure as the building during the test.
-
Turn on the gauge and put it the
PR/ AH
mode by pressing the
MODE
button. The icon “NSOP” will begin to
flash in the
Channel A
display, indicating that the
PR/ AH
measurement feature has been initiated. At this
point, the gauge is monitoring the real-time
Channel A
NSOP
pressure, but is not recording the reading. The
Channel B
display is not active at this time.
-
Press the
START
button to begin the
NSOP
measurement
procedure on
Channel A
. Once the
START
button is
pressed, the icon “NSOP” stops flashing and the gauge
begins recording a
long term average
NSOP
pressure
reading on
Channel A
. During the measurement procedure,
the
Channel B
display is used as a timer to let the user
know how long (in seconds) the NSOP measurement has been active. The longer the measurement time,
generally the more stable the reading typically becomes. In the screen to the right, the measured NSOP pressure
is 56.7 Pascals (measured over the past 30 seconds).
-
Once you are satisfied with the
NSOP
reading, press the
ENTER
key to accept and enter the reading into the
gauge. Turn off the air handler, and leave the static pressure probe in place and connected to the gauge.
5.7.b Step 2: Measuring the TFSOP and Adjusted Air Handler Flow
-
Once the
NSOP
measurement is made and entered into the gauge (
Step 1
), the gauge is set up to simultaneously
measure the Test Flow System Operating Pressure (
TFSOP
) on
Channel A
, and to display the estimated air
handler flow rate on
Channel B
.
-
Install the test device used to measure air handler flow (either a TrueFlow Metering Plate, or a Duct Blaster
Fan). Connect the test device to
Channel B
. Refer to the TrueFlow or Duct Blaster operation manuals for
installation instructions.
-
Select the installed test device and device configuration on the DG-700 using the
DEVICE
and
CONFIG
buttons.
If Using a TrueFlow Metering Plate
-
Turn on the air handler.
Channel A
will now display the
TFSOP
reading from the static pressure probe, and
Channel B
will display adjusted air handler flow. The flow
rate estimate shown on
Channel B
is determined by
continuously adjusting the measured air flow from the
TrueFlow Metering Plate using a flow resistance correction
factor calculated from the
NSOP
and
TFSOP
pressure readings. If the readings are fluctuating, change the time
averaging setting to
5 second
,
10 second
,
or long-term average
using the
TIME AVG
button.
21
Operating Instructions
for the DG700
