TEC DB-PR700 User manual

Copyright 2011 The Energy Conservatory (revised 02-11)
Fan Configuration Flow Range (cfm)
For Series B Duct Blaster
Open (no Flow Ring) 1,500 - 600
Ring 1 800 – 225
Ring 2 300 – 90
Ring 3 125 – 10
Quick Guide DB-PR700
One-Point 25 Pascal Total Leakage Duct Pressurization Test (blowing air into the duct system)
Using the 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 

 temporary register sealing material provided with your Duct Blaster, 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 building and outside to prevent changes in building 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 the 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 that will be
coming 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 a
piece of tubing through the temporary register
seal.
b) Connect tubing to the DG-700 as shown in
the illustration to the right.
** Your DG-700 gauge is compatible with Cruise Control if the CONFIG, CLEAR, START and ENTER keys have additional red
lettering below the main black script. Cruise Control also requires a Duct Blaster speed controller with a 3.5 mm communication jack
installed on the side of the controller box, and a fan control cable.
Connect the Red
tubing to the
Chan B Input tap.
The other end of
the Red tubing
should be
connected to the
brass tap in the
middle of the DB
fan housing.
Connect Chan A Ref
tap to inside of
building (if gauge is
located in the
building, leave this
tap open). Be sure
window is open.
Connect Chan B Ref
tap to space where
the fan is installed (if
fan and gauge are in
the same space,
leave this tap open).
Connect the Green (or
Clear) tubing to the
Chan A Input tap. The
other end of the Green
tubing should be
connected to the duct
system (by either
inserting into a sealed
register, or connecting
to the end of the
installed static
pressure probe).
Optional fan
control cable
(for Cruise Control).

Copyright 2011 The Energy Conservatory (revised 02-11)
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 gauge 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 total 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.)
c) Check (and adjust if necessary) the selected test Device (i.e. fan) and Configuration (i.e. Flow Ring) shown in the upper part of
the gauge display to match the fan and Flow Ring being used in the test. For example, the Device icon for the Series B Duct Blaster
fan is DB B, and the Configuration icon for Ring 2 is B2. Press the DEVICE button to change the selected fan. Press the CONFIG
button to change the selected Flow Ring.
d) Turn on the Duct Blaster fan.
If Using Cruise Control:
Turn the Duct Blaster speed controller to the “just on” position (i.e. turn the controller knob all the way down counter-clockwise
and flip the on/off switch to “ON” – the fan will not be turning). Now press the Begin Cruise (Enter) button. The Channel A
display will now show the number 25 (your target Cruise pressure). Press the Start Fan (Start) button. The Duct Blaster fan will
now slowly increase speed until the duct pressurization displayed on Channel A is approximately 25 Pascals.
If Manually Controlling Fan:
Turn on the Duct Blaster fan controller and slowly turn the fan controller knob clockwise. As the fan speed increases, the duct
pressurization displayed on Channel A should also increase. Continue to increase the fan speed until the duct pressurization
shown on Channel A is between 20 and 30 Pascals. Do not waste time adjusting and re-adjusting the fan speed control to
achieve a test pressure of exactly 25 Pascals.
e) Channel B will now display the One-Point 25 Pascal Total Duct Leakage estimate. Record this number. If the leakage estimate
is fluctuating more than desired, try changing the Time Averaging setting on the gauge by pressing the TIME AVG button and
choosing the 5or 10 second or Long-term averaging period. (If “------“ or “LO” appear on Channel B, see #5 below).
f) Turn off the Duct Blaster fan. If you are using Cruise Control, this is done by pressing the Stop Fan (Clear) button.
5. “-----” or “LO” appearing on Channel B
Whenever “-----” or “LO” appears on Channel B in the PR/ FL @ 25 Mode, the DG-700 can not calculate a reliable leakage
estimate. The messages “-----” and “LO” appear on Channel B under the following three conditions:
a) “-----” is continuously displayed when the duct test pressure from Channel A is below a minimum value of 5 Pascals. Estimating
duct leakage results when the test pressure is below this value may result in large errors. If possible, install a larger Flow Ring or
remove the Flow Rings to generate more fan flow.
b) “LO” is continuously displayed when there is negligible air flow through the test device.
c) “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. install a Flow Ring or a smaller Flow Ring).
Note: If you change the Flow Ring on the fan, be sure to change the Configuration setting on the gauge to match the installed Ring.