Retrotec Commercial 441 and 451 DucTester - Manual (Page 21)

Page 21 of 56
©Retrotec Inc. 2015
5.3 Step 3 – Connect DucTester to ducts
The DucTester has a 4 inch (100 mm) flex with a 4 inch (100 mm) collar that connects to the duct
system. When considering where to connect the DucTester to the duct system, it is important to think
about airflow restriction and accessibility. Always pressurize first. If you pass and need to test in the
other direction, do so afterwards.
Figure 11 Model 400 Blower set up to test ducts prior to installation of the Flow Plug that is needed to measure flow.
1. Attach the 4 inch (100 mm) Flange to the ductwork.
2. Attach 4 inch collar on flex to flange.
3. Connect DucTester exhaust to flex with the 2.5 inch (63mm) connector.
4. Install Range 47 Flow Plug. Range 47 provides 52 to 206 CFM, which is sufficient to test most
duct runs. Refer to Table 4 Minimum and Maximum flows for all Range Plugs and Table 4.
5.3.1. Select a test direction
Duct leakage can be measured by blowing air into the ducts to pressurize the ducts, or by pulling air out
of the ducts to depressurize the ducts. Program guidelines may specify a particular test direction but
generally in the USA ducts are pressurized only and in Europe they are tested in both directions. Both
test directions provide similar results, however pressurization testing is faster.