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Appendix A
A.2 One-Point 25 Pascal Total Leakage Duct Pressurization Test Using the Series B Minneapolis
Duct Blaster and DG-700 Digital Gauge
1.
Connect the Duct Blaster fan to the duct system.
a)
Choose a location to install the Duct Blaster fan. In single, double or triple returned systems, the largest and
closest return to the air handler is usually the best choice. Note: In multi-return systems (a return in every room),
installing at the air handler cabinet is often best.
b) Remove any remote filters from the chosen return and then connect the black square transition piece to the return
using temporary tape. Completely seal the remaining open area of the return with tape.
c)
Pull the Duct Blaster fan and flex duct out of the carrying case. Connect the flex duct to the exhaust side of the
fan (i.e. the side with the metal guard) using the round transition piece and connect trim. Connect the open end of the
flex duct to the square transition piece using the velcro strap on
the flex duct.
d) Connect the fan speed controller to the fan and plug it into a
grounded power outlet.
e)
Install the Flow Ring which you think best matches the
needed fan flow.
f)
If your DG-700 gauge and fan speed controller are
compatible with Cruise Control, install the fan control cable into the 3.5 mm communication jacks located on top of
the DG-700 and on the side of the speed controller (otherwise skip this step).
2.
Prepare the duct system and house for the Test.
a)
Adjust the HVAC system controls so that the air handler does not turn on during the Test.
b) Temporarily seal off all remaining supply and return registers, and combustion or ventilation air inlets which are
connected to the duct system. Use Duct Mask
or use painters tape and paper.
c)
Turn off any exhaust fans, vented dryers, and room air conditioners.
d) Remove all central filters (i.e. in air handler or return plenum).
e)
Open a door or window between the house and outside to prevent changes in house pressure when the Duct
Blaster is running.
f)
If the Duct Blaster is installed in an attic, garage or crawlspace - open vents or access panels or doors from these
spaces to the outside.
3.
Connect tubing to DG-700 Pressure Gauge.
a)
Select a location to measure duct
pressure. The best location for measuring duct
pressure is often in the supply trunkline or
plenum. Drill a small hole (1/4" to 3/8" OD)
into the duct to allow a static pressure probe to
be installed. Install the static pressure probe
with the end of the probe pointing into the air
flow from the Duct Blaster fan. If the duct
system is reasonably airtight (e.g. less than
200 cfm25 of leakage), duct pressures can be
measured at any supply register by inserting
the end of the tubing through the temporary
register seal.
b) Connect tubing to the DG-700 as shown
in the illustration to the right.
4.
Conducting the Test.
a)
Turn on the gauge by pressing the ON/OFF button.
b) Press the MODE button three times to put the guage into the PR/ FL @25 Mode. In this Mode, Channel A is
used to measure duct system pressure while Channel B is used to display estimated duct leakage at a test pressure of
25 Pascals. (The leakage estimate shown on Channel B is determined by mathematically adjusting the actual air flow
from the Duct Blaster fan using the Channel A duct system pressure reading and a Can't Reach Pressure factor.)
Quick Guides for Using the DG-700 with Energy Conservatory Test Devices
temporary register sealing material provided with your Duct Blaster,
To Duct System
(insert into register
or connect to static
pressure probe)
Connect to inside of house (if
gauge is installed in the house,
leave this tap open). Be sure
window is open.
28
Fan Configuration
Flow Range (cfm)
For Series B Duct Blaster
Open (no Flow Ring)
Ring 1
Ring 2
Ring 3
Operating Instructions
1,500 - 600
800 – 225
300 – 90
125 – 10
To Duct Blaster Fan
(brass tap in middle
of fan housing)
Connect to space where
fan is installed (if fan and
gauge are in the same
space, leave open).
for the DG700
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