
Chapter 5
Pressure/Air Handler Flow Mode
Once a test device is selected, the configuration of the device (i.e. flow rings, or plate installed) can be selected by
pressing the
CONFIG
button. The currently selected device configuration is shown in the Config section of the
gauge display.
5.4 “-----”or “LO” Displayed on Channel B
Whenever “
-----
” or “
LO
” appears on
Channel B
in the
Step 2
part of the
PR/ AH
procedure, the DG-700 can not
display a reliable air handler flow estimate. The messages “
-----
” and “
LO
” appear on
Channel B
under the
following three conditions:
“
-----
” is continuously displayed when either the recorded
NSOP
reading, or the current
TFSOP
reading is
below 2 Pa.
“
LO
” is continuously displayed when there is negligible air flow through the test device.
“
LO
” alternates with a flow reading when the air flow reading through the device is unreliable (i.e. you are
trying to measure a flow outside of the calibrated range of the test device in its current configuration). If
possible, you should change the test device configuration to match the flow rate being measured (e.g. if using a
Duct Blaster fan, install a flow ring or a smaller flow ring).
5.5 Changing the Air Handler Flow Units
When in the
PR/ AH
mode, the DG-700 can display air handler flow on
Channel B
in units of
CFM
,
m
3
/hr
, and
l/s
. The default air flow unit is
CFM
. To change the flow units for
Channel B
, press the
UNITS
button while in the
Step 2
part of the procedure. The selected flow units are shown on the gauge
display directly below the
Channel B
readings. The pressure unit for
Channel A
is always
Pascals
when in the
PR/ AH
mode.
5.6 Changing the Time Averaging Period for the Step 2 Procedure
To change the selected time averaging period for the
Step 2
part of the
PR/ AH
procedure, press the
TIME AVG
button. The selected time averaging period is shown in the
TIME AVG
portion of the
gauge display. (See
Section 1.5
for an overview of the time averaging periods.) During the
Step 1
part of
the procedure, the time average feature is always set to
long-term average
.
5.7 Test Procedure For Measuring Air Handler Flow
5.7.a Step 1: Measuring the NSOP
-
Open a window or door between the building and outside to prevent pressure changes in the building during the
test. If the air handler fan is installed in an unconditioned zone (e.g. crawlspace, attic), open any vents or access
doors connecting that zone to the outside (or to the building) to prevent pressure changes in the zone during the
test.
-
Make sure all supply and return registers are open and untapped. Replace filters if they are dirty (or keep dirty
filters in place if you want to measure flow in a "as found" condition). Turn on the air handler.
20
Operating Instructions
for the DG700
Содержание DG-700
Страница 1: ...Operating Instructions for the DG 700 Pressure and Flow Gauge...
Страница 2: ......