System Effect: CASE STUDY
Kevin Underwood, TBE
Engineered Air Balance Co., Inc.
common term used to describe some inlet and
outlet conditions that affect the performance of fans
is “system effect.” The term refers to the results
obtained after the fan was tested in a laboratory compared
with how the fan was installed. A case study was performed
on an exhaust fan that was not performing as submitted on
recent project. The following was the original submittal data
for the subject fan:
Flat Blade Centrifugal Blower
n Model 245 CPS
n Design SP = 1.00” w.c.
n Design Motor HP = 5.0
n Design CFM = 8195
n Design Fan RPM = 1080
After the exhaust was proportioned within the system, the fan was
operating at 80% of the design CFM, and the motor was operating at
STEP 1: Evaluate the air balance measurements and compare them with
the fan curve data. The air balance measurements are correct. The missing
component is the effect of the back draft damper on the discharge of the fan.
This data has to be added back into the air balance measurements.
TAB Journal Spring 2013
Table of Contents for the Digital Edition of Tab Journal Spring 2013