Retrotec Commercial 441 and 451 DucTester - Manual (Page 20)

Page 20 of 56
©Retrotec Inc. 2015
5.2
Step 2 – Determine test criteria and prepare the ducts
How the ducts are prepared will be impacted by the test
pressure and test direction required. Determine the specified
Leakage Class and Test Pressure in order to decide how to break
up the ducts in sections for the test. You will need to have
sufficient blower power to take the ducts up to the specified test
pressure. In other words, you should have enough flow to test
the ducts if they just pass.
Extremely leaky ducts may require much more flow to get them
to the test pressure but that is not needed to see if they fail.
After all it is unfair to provide excessive amounts of flow if you
can determine the ducts will fail anyway. Blowing power is
expensive.
Once you determine the maximum flow you’ll need, use
Table 2 to see if your Model 450 is up to the task.
If Test Pressure is not specified, use a Pressure Class of 1 in WC
except upstream of VAV boxes, use 2 in WC. Use a positive test
pressure unless specified otherwise. Use 1000 Pa in Europe.
Select a limited section of duct that you have sufficient power to
test. Measure the duct surface area in square feet. See Table 3.
Ensure sealing is complete. Ensure sealing materials have cured for the prescribed time or at least 24
hours OR follow manufacturer’s directions.
Blank off and seal the tested ductwork by inserting temporary plugs plates, sheets, balloons, bags into
intentional openings.