TAB Journal Summer 2019 - 9

still had the same results. We talked to the general contractor,
explained our fi ndings and how there were still issues. It was
then suggested that we should try switching the fan motors
to cover all the bases. The motors were swapped a few days
later and we came back to do more testing. So now we had a
program card and a motor from a box that was spot-on in the
box that was having issues. The box was retested and we still
had the same results with the box. The primary airflow was
approximately 50 percent above design.

issue directly with the mechanical contractor and told them
how we planned on balancing these boxes. We explained the
who, what, where, when, and why so they knew it was getting
done correctly as opposed to what we were directed to do.

The manufacturer was then called by the engineer and general
contractor. They explained the problem and the manufacturer
told them to send the box in for testing. Since this wasn't a
single box issue, they didn't believe that sending one box back
was an option. The manufacturer swore time and time again
that their box, if sent back, would do exactly what the voltageto-CFM chart said it would. Finally, the manufacturer came
out to the jobsite where we tested the boxes again. Once more,
we proved that the VAV's airflow would not be correct if set
up as the manufacturer specified.

In the end, the building worked as intended. The boxes were
balanced by traversing every inlet primary air duct to calibrate
and set the primary air. The fan powered side of the box was
then done using the voltage/CFM chart. The fan CFM was
verified by traversing the discharge of the box. If the discharge
was above design, the voltage input was then manipulated to
get the CFM to design. Some boxes did not need any changes,
but others did. Once all the boxes were balanced on the
respective air handler that served them, the air handler was
tested. The air handler total was within the design amount of
the primary box totals. That would not have been the case if
the boxes were set up as specified. The air handler would have
been delivering a lot more air than what the boxes totaled.

After all of this, we were still directed to use the
manufacturer's method. As professionals, we could not
knowingly set up a building incorrectly. We discussed the

In closing, it is always necessary to make sure that readings
are correct. Laboratory test results sometimes may not transfer
over to field installs. Verify, verify, verify.

Connecting engineers,
building owners,
commissioning
providers and other
industry professionals
with AABC
Learn More about the AABC
Industry Partner Program at
aabc.com/industry-partners

TAB Journal Summer 2019

9


http://www.aabc.com/industry-partners

TAB Journal Summer 2019

Table of Contents for the Digital Edition of TAB Journal Summer 2019

TAB Journal Summer 2019 - Cover1
TAB Journal Summer 2019 - Cover2
TAB Journal Summer 2019 - 1
TAB Journal Summer 2019 - 2
TAB Journal Summer 2019 - 3
TAB Journal Summer 2019 - 4
TAB Journal Summer 2019 - 5
TAB Journal Summer 2019 - 6
TAB Journal Summer 2019 - 7
TAB Journal Summer 2019 - 8
TAB Journal Summer 2019 - 9
TAB Journal Summer 2019 - 10
TAB Journal Summer 2019 - 11
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TAB Journal Summer 2019 - 16
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TAB Journal Summer 2019 - 20
TAB Journal Summer 2019 - Cover3
TAB Journal Summer 2019 - Cover4
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